Seguimiento general en EEUU

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Jue Jun 15, 2017 10:47 pm

De buenas a primeras, salta un riesgo moderado por tiempo severo entre el noreste de Oklahoma y el sur/sudeste de Kansas. Persiste un 2% de probabilidades de tornados para el noreste de Oklahoma, sur de Kansas y el extremo sudoeste de Missouri. Viento y granizo, los riesgos más importantes.
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% de viento.
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Granizo.
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Discusión.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Thu Jun 15 2017

Valid 160100Z - 161200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
KANSAS INTO NORTHEAST OKLAHOMA...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
SOUTHEASTERN KANSAS INTO NORTHEASTERN OKLAHOMA AND SOUTHWEST
MISSOURI...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN AND
EASTERN OKLAHOMA INTO IOWA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS WEST
TEXAS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
PLAINS INTO PARTS OF THE DEEP SOUTH AND APPALACHIANS...

...SUMMARY...
A localized significant damaging wind threat will persist this
evening across southeast Kansas into northeast Oklahoma, with large
hail likely as well extending from west Texas to Iowa.

...Southeast Kansas into northeast Oklahoma and vicinity...
A large cluster of storms continues to race southeastward across KS
with wind gusts in excess of 70 mph measured and widespread 50-60
mph winds. The air mass remains very unstable per 00Z soundings, and
this should support a continued severe wind threat downstream into
northeastern OK this evening. In addition, sporadic large hail is
expected.

..Jewell.. 06/16/2017

Próxima actualización: 06:00z.
-----------------------------------------
Watchs vigentes.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 333
NWS Storm Prediction Center Norman OK
220 PM CDT Thu Jun 15 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Western Oklahoma
Texas Panhandle

* Effective this Thursday afternoon and evening from 220 PM until
900 PM CDT.

* Primary threats include...
Scattered large hail likely with isolated very large hail events
to 3 inches in diameter possible
Scattered damaging wind gusts to 70 mph possible

SUMMARY...Thunderstorms will intensify across the watch area this
afternoon and early evening, posing a risk of very large hail and
damaging winds.

The severe thunderstorm watch area is approximately along and 60
statute miles east and west of a line from 30 miles south southeast
of Plainview TX to 30 miles northwest of Alva OK. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 332...

AVIATION...A few severe thunderstorms with hail surface and aloft to
3 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
27030.

...Hart

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 335
NWS Storm Prediction Center Norman OK
510 PM CDT Thu Jun 15 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
West/southwest Texas

* Effective this Thursday afternoon from 510 PM until Midnight
CDT.

* Primary threats include...
Scattered large hail and isolated very large hail events to 3
inches in diameter possible
Isolated damaging wind gusts to 70 mph possible

SUMMARY...As at least isolated stronger storms develop across the
region through early evening, modest deep-layer winds in conjunction
with strong heating and moderate buoyancy will support some
high-based severe thunderstorms including a few supercells. Large
hail should be the main risk, although a hot/deeply mixed
environment could support severe-caliber downdrafts.

The severe thunderstorm watch area is approximately along and 65
statute miles east and west of a line from 60 miles north northeast
of Big Spring TX to 25 miles south southeast of Fort Stockton TX.
For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU5).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 332...WW 333...WW 334...

AVIATION...A few severe thunderstorms with hail surface and aloft to
3 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
34015.

...Guyer

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 336
NWS Storm Prediction Center Norman OK
640 PM CDT Thu Jun 15 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Southern and eastern Iowa
Northeast Kansas
Northern Missouri
Southeast Nebraska

* Effective this Thursday night and Friday morning from 640 PM
until 100 AM CDT.

* Primary threats include...
Isolated very large hail events to 2 inches in diameter possible
Isolated damaging wind gusts to 70 mph possible

SUMMARY...Multiple corridors of storms including some splitting
supercells will continue to progress generally eastward across the
region through the evening hours. Large hail and locally damaging
wind gusts are the main risk.

The severe thunderstorm watch area is approximately along and 75
statute miles north and south of a line from 20 miles northeast of
Cedar Rapids IA to 20 miles west of Falls City NE. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU6).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 332...WW 333...WW
334...WW 335...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
25030.

...Guyer

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 337
NWS Storm Prediction Center Norman OK
705 PM CDT Thu Jun 15 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Northwest Arkansas
Southern and eastern Kansas
Western Missouri
Northern Oklahoma

* Effective this Thursday night and Friday morning from 705 PM
until 200 AM CDT.

* Primary threats include...
Widespread damaging winds likely with isolated significant gusts
to 80 mph possible
Scattered large hail and isolated very large hail events to 3
inches in diameter possible
A tornado or two possible

SUMMARY...An increasingly well organized MCS will continue to
gradually accelerate southeastward this evening across southern
Kansas into western Missouri, northern Oklahoma and possibly
northwest Arkansas. Relatively widespread wind damage is possible
aside from large hail and possibly a line-embedded brief tornado
risk.

The severe thunderstorm watch area is approximately along and 75
statute miles north and south of a line from 70 miles north
northeast of Monett MO to 30 miles west of Medicine Lodge KS. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 333...WW 334...WW
335...WW 336...

AVIATION...A few severe thunderstorms with hail surface and aloft to
3 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 650. Mean storm motion vector
33045.

...Guyer

-------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1038
NWS Storm Prediction Center Norman OK
1136 AM CDT Thu Jun 15 2017

Areas affected...Portions of south-central Kentucky...Middle
Tennessee...northwest Alabama and northern/central Mississippi

Concerning...Severe potential...Watch possible

Valid 151636Z - 151830Z

Probability of Watch Issuance...40 percent

SUMMARY...Severe thunderstorms are expected to increase in coverage
through this afternoon with a risk for damaging winds and large
hail. Trends will be monitored for the possibility of a severe
thunderstorm watch.

DISCUSSION...Thunderstorms were located along a persistent outflow
boundary from northwest Mississippi northeast into Middle
Tennessee/south-central Kentucky at of 1630z. This boundary, and
associated thunderstorm activity, will continue to move
south/southeast into a moist and increasingly unstable air mass
characterized by moderate/strong surface-based buoyancy but modest
deep-layer shear. Latest visible satellite imagery shows increasing
surface-based instability and towering cumulus both along and in
advance of the boundary-associated storms. An increase in storm
coverage and intensity is expected over the next few hours with a
primary risk for damaging winds due to water loading of updrafts.
The degree of instability suggests that isolated instances of large
hail will also be possible. Despite the weak vertical shear and
overall slow storm motions, some potential exists for storm outflows
to congeal with time, resulting in more concentrated corridors of
damaging wind potential.

Convective trends will continue to be monitored and a severe
thunderstorm watch may be needed if confidence increases in the
coverage of severe wind/hail risk.

..Bunting/Hart.. 06/15/2017

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Mesoscale Discussion 1039
NWS Storm Prediction Center Norman OK
1249 PM CDT Thu Jun 15 2017

Areas affected...A large part of Kansas

Concerning...Severe potential...Severe Thunderstorm Watch likely

Valid 151749Z - 152015Z

Probability of Watch Issuance...95 percent

SUMMARY...A Severe Thunderstorm Watch is forthcoming.

DISCUSSION...Cumulus fields are becoming increasingly agitated along
a composite boundary extending west-east from west of Russell to
southwest of Hill City. Explosive thunderstorm development is
expected within this corridor in the 1830Z-2000Z time frame.
Widespread strong insolation is supporting the erosion of modest
capping aloft, and an upward trend is already noted in
shallow-convective processes -- thus relatively early convective
development is expected. SBCAPE of 4000-6000 J/kg is noted south of
the boundary, with 25-40 kt of effective shear. Initial supercell
structures capable of very large hail and severe winds will be
likely. Given the anticipated concentration of intense cold pools
aided by DCAPE of 1300-1700 J/kg, upscale growth into a
east-southeastward/southeastward-moving bowing MCS will likely occur
thereafter. Widespread severe winds are expected, and localized
pockets of 70-80 mph winds are also likely with line-embedded
meso-vortices as convection advances across the region through into
the late afternoon/early evening hours.

..Cohen/Hart.. 06/15/2017

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Mesoscale Discussion 1040
NWS Storm Prediction Center Norman OK
0203 PM CDT Thu Jun 15 2017

Areas affected...Portions of the TX Panhandle and South
Plains...western OK...far south-central KS

Concerning...Severe potential...Watch possible

Valid 151903Z - 152130Z

Probability of Watch Issuance...60 percent

SUMMARY...The area is being monitored for an increase in the
potential for severe thunderstorms, including the risk for
significant severe hail. The issuance of a Severe Thunderstorm Watch
is possible.

DISCUSSION...Towering cumulus development continues along a
northeast-southwest-oriented dryline across the TX Panhandle. The
dryline arches southward near the NM/West TX border, and additional
high-based cumulus fields are becoming evident over western sections
of the TX South Plains. Despite an overall dearth of deep ascent,
baroclinic circulations along the dryline are being amplified by
intense surface heating, with temperatures near 100F in some
locations on the immediate dry side of the dryline. Convection will
likely deepen, with isolated to widely scattered thunderstorms
developing in the next couple of hours.

Long, straight mid/high-level hodographs associated with 25-40 kt of
effective shear will foster splitting supercells. Large normalized
CAPE in the hail-growth zone aloft associated with very steep
midlevel lapse rates, along with MLCAPE around 2000-3500 J/kg,
suggest intense updrafts should evolve with severe hail -- and
baseball-size hail will be possible. Storms will develop into far
south-central KS and into western OK with time into the evening
hours. Large DCAPE amid the well-mixed boundary layer will support a
risk for severe wind gusts -- locally bolstered when congealing cold
pools facilitate convective clustering.

Given the lack of stronger deep ascent, there is some uncertainty
regarding the timing of more substantial increase in severe risk.
Moreover, anticipated severe coverage is somewhat unclear,
especially given only weakly convergent low-level flow. However,
appreciable conditional severe risk is in place for this afternoon
into the evening.

..Cohen/Hart.. 06/15/2017

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Mesoscale Discussion 1041
NWS Storm Prediction Center Norman OK
0240 PM CDT Thu Jun 15 2017

Areas affected...Portions of southwest TX and extreme southeast NM

Concerning...Severe potential...Watch possible

Valid 151940Z - 152215Z

Probability of Watch Issuance...40 percent

SUMMARY...The area is being monitored for some increase in the
severe-thunderstorm risk this afternoon, which could persist into
the evening. While Watch issuance is not presently likely,
convective and environmental trends will be monitored for possible
Severe Thunderstorm Watch issuance.

DISCUSSION...Cumulus fields are becoming increasingly defined over
the higher terrain from southwest TX into southeast NM -- in
proximity to a north-south-oriented dryline. Continued
terrain-driven circulations, and baroclinic circulations attendant
to the dryline, should foster increasing convective coverage and
intensity during the next few hours. The air mass is increasingly
unstable with eastward extent from the dryline, as the relatively
moist boundary layer has become hot/well mixed with dewpoints
holding in the 50s and 60s. With midlevel lapse rates around 8.5-9.5
C/km, MLCAPE around 2500-4000 J/kg will support updraft
intensification as convection spreads across the area into the
evening hours. The presence of 25-40 kt of effective shear could
support supercell structures with large hail, and large DCAPE would
support some potential for severe wind gusts. Given the lack of any
substantive deep ascent, and given comparatively even weaker surface
convergence compared to locations farther north, severe coverage may
be limited. However, given the appreciable conditional severe risk,
some potential for Watch issuance exists -- especially if the risk
for greater severe coverage were to become apparent.

..Cohen/Hart.. 06/15/2017

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Mesoscale Discussion 1042
NWS Storm Prediction Center Norman OK
0301 PM CDT Thu Jun 15 2017

Areas affected...portions of western Pennsylvania...northern West
Virginia

Concerning...Severe potential...Watch unlikely

Valid 152001Z - 152200Z

Probability of Watch Issuance...5 percent

SUMMARY...Thunderstorms will pose a risk for isolated damaging gusts
through the remainder of the afternoon, however a watch is not
anticipated.

DISCUSSION...Thunderstorms over western Pennsylvania have loosely
organized into short line segments this afternoon, aided in part by
weak ascent associated with a convectively-modulated mid-level
impulse moving east across Ohio. A 45-kt wind gust was reported with
the line of storms at KHLG earlier this afternoon. Generally weak
surface-based buoyancy has developed in advance of the line, with
effective shear values generally below 25 kts. Nevertheless, the
line segments will be capable of additional isolated strong/damaging
gusts for a few more hours as storms move northeast. The overall
severe risk should remain too isolated to warrant a severe
thunderstorm watch.

..Bunting/Hart.. 06/15/2017

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Mesoscale Discussion 1043
NWS Storm Prediction Center Norman OK
0329 PM CDT Thu Jun 15 2017

Areas affected...Much of Kansas

Concerning...Severe Thunderstorm Watch 332...

Valid 152029Z - 152230Z

The severe weather threat for Severe Thunderstorm Watch 332
continues.

SUMMARY...Severe Thunderstorm Watch 332 remains in effect.

DISCUSSION...Explosive thunderstorm development has been underway in
Ellis and Trego Counties -- along a west-east boundary. A
supercell-cluster mode has typified this activity, and continued
upshear development and expanding/amalgamating, convectively
generated cold pools may breed upscale growth of this activity
during the next couple of hours. The Hays KS AWOS has already
measured a 53-kt gust.

As such, a bowing MCS could materialize across parts of central KS
during the next couple of hours as this activity spreads downshear.
The MCS would spread east-southeastward and southeastward into the
evening -- aided by preferential cell development on the southern
and eastern flanks of the growing cold pool where strongly buoyant
inflow exists. The special 18Z sounding from Topeka KS indicates
around 3500 J/kg of MLCAPE, and even more substantial MLCAPE exists
with southward extent from the boundary where dewpoints have not
mixed out as much. The 17Z Lamont OK sounding indicates around 50 kt
of effective shear, suggesting increasing potential in
forward-propagating MCS formation. Wind gusts of 60-80 mph winds are
expected -- enhanced in conjunction with line-embedded mesovortices.
If confidence in a more precise corridor of damaging/destructive
winds were to become apparent, it is possible that some
consideration could be given to the issuance of a Particularly
Dangerous Situation Severe Thunderstorm Watch.

More isolated convection backbuilding along the boundary in western
KS may also pose severe potential into parts of southwest KS during
the next few hours. Furthermore, splitting supercells south of the
area -- across parts of Watch 333 -- may eventually develop into
parts of far south-central KS later this afternoon, with severe
hail/wind potential.

..Cohen.. 06/15/2017

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Mesoscale Discussion 1044
NWS Storm Prediction Center Norman OK
0424 PM CDT Thu Jun 15 2017

Areas affected...Portions of eastern Alabama and western/central
Georgia

Concerning...Severe potential...Watch possible

Valid 152124Z - 152230Z

Probability of Watch Issuance...40 percent

SUMMARY...A band of strong/severe storms will continue southeast
through this evening. Pockets of damaging winds will continue to be
the main threat.

DISCUSSION...Regional radar data are showing a line of storms
pushing southeast across eastern Alabama and northern Georgia early
this evening. Ahead of this line, a hot/moist boundary layer and
relatively uncapped environment are supporting continued storm
propagation as outflow surges southeast. The 12Z FFC sounding,
modified for current surface conditions, suggests steep low-level
lapse rates resulting in DCAPE values upwards of 1000 J/kg. In turn,
strong downdraft momentum will maintain a threat of gusty, damaging
winds. Furthermore, southeastward acceleration and weak anvil-layer
flow have resulted in the organization of a trailing stratiform
precipitation shield, likely further enhancing the wind threat. As
such, watch issuance may be necessary early this evening.

..Picca/Guyer.. 06/15/2017

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Mesoscale Discussion 1045
NWS Storm Prediction Center Norman OK
0511 PM CDT Thu Jun 15 2017

Areas affected...Portions of the mid Missouri Valley to eastern Iowa

Concerning...Severe potential...Watch possible

Valid 152211Z - 152315Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated thunderstorms may develop through the evening
hours, with an attendant potential for large hail and damaging
winds. Observational trends are being monitored for possible watch
issuance.

DISCUSSION...Visible satellite late this afternoon depicts pockets
of agitated/towering cumulus across the mid Missouri Valley and
vicinity this evening. Also noted in satellite imagery,
mid/upper-level cloud cover continues to overspread these cumulus
fields, suggesting a speed maximum may be providing weak large-scale
ascent. Despite fairly weak low-level convergence along a front
extending northeast, the influence of this system may be sufficient
for isolated convective initiation over the next several hours.
Moreover, guidance suggests development may be bolstered along the
northern fringe of an anvil spreading north from a convective system
over Kansas. An array of mesoscale/microphysical processes (e.g.,
differential heating, anvil seeding, gravity waves) may be the cause
of such bolstered development; regardless, visible satellite appears
to confirm the notion of enhanced development along the leading edge
of the anvil. Steep mid-level lapse rates (and related strong
buoyancy), as well as adequate westerly mid/upper flow, may be
sufficient for a few organized/rotating updrafts, capable of large
hail and damaging winds. Therefore, trends are being monitored for
possible watch issuance over the next few hours.

..Picca/Guyer.. 06/15/2017

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Mesoscale Discussion 1046
NWS Storm Prediction Center Norman OK
0545 PM CDT Thu Jun 15 2017

Areas affected...Western Oklahoma and much of the Texas Panhandle

Concerning...Severe Thunderstorm Watch 333...

Valid 152245Z - 152345Z

The severe weather threat for Severe Thunderstorm Watch 333
continues.

SUMMARY...The severe threat continues across WW 333.

DISCUSSION...Isolated-to-scattered convective activity has evolved
across WW 333 ahead of a dryline located from near DDC in
southwestern Kansas to AMA to HOB in southeastern New Mexico. A
strongly unstable pre-convective airmass - supported by very steep
tropospheric lapse rates, 60s to low 70s dewpoints, and 90s F
surface temperatures - is supporting a risk of large hail (perhaps
significant) and damaging wind gusts with this activity. Enough
deep shear exists for some storm organization (including occasional
supercell structures) although weaknesses in the low- and mid-level
kinematic fields are supporting mostly outflow dominant storms.
Some southeastward propagation of these storms is observed via radar
and satellite observations. The outflow-dominant nature of these
storms may allow for localized linear segments to develop as these
storms propagate southeastward over the next 1-2 hours, perhaps
enhancing the existing damaging wind potential with this activity.

..Cook.. 06/15/2017

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Mesoscale Discussion 1047
NWS Storm Prediction Center Norman OK
0558 PM CDT Thu Jun 15 2017

Areas affected...Portions of Kansas and far northern Oklahoma

Concerning...Severe Thunderstorm Watch 332...

Valid 152258Z - 160000Z

The severe weather threat for Severe Thunderstorm Watch 332
continues.

SUMMARY...Congealing severe thunderstorms will accelerate
east/southeast across Kansas this evening, with a continued threat
of damaging wind gusts, a few of which could be significant.

DISCUSSION...Several clusters of severe thunderstorms, with a few
embedded mesoscale vortices, are evolving generally southeastward
this evening. The overall evolution appears to suggest upscale
growth into a bowing complex stretching from Clay County southward
to Marion County as of 2250Z. Additionally, low-level
confluence/warm advection is enhancing storm propagation to the west
towards Rice County (noted in the recent appearance of several ZDR
columns and expansion of low-level hydrometeor size sorting
signatures). Reflectivity, velocity, and dual-pol data also suggest
a surge or rear-inflow drying/winds pushing across Rice County. With
storm-relative inflow bolstered by south/southeasterly winds of
15-20 kt and strong instability ahead of the organizing complex,
storms will likely continue to accelerate east/southeastward, with
the potential for one or more swaths of damaging winds across
southern/eastern Kansas. Indeed, a few significant severe gusts
remain possible. As such, an extension and/or replacement of Watch
332 will likely be coordinated within the hour.

..Picca.. 06/15/2017

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Mesoscale Discussion 1048
NWS Storm Prediction Center Norman OK
0606 PM CDT Thu Jun 15 2017

Areas affected...portions of the upper peninsula of Michigan

Concerning...Severe potential...Watch unlikely

Valid 152306Z - 160000Z

Probability of Watch Issuance...5 percent

SUMMARY...An isolated hail threat will exist with activity entering
the northern Upper Peninsula of Michigan. A WW issuance is not
anticipated for this activity.

DISCUSSION...A small cluster of thunderstorms, initially located
over southern Lake Superior, has organized and began to propagate
southeastward into eastern portions of the Upper Peninsula of
Michigan over the past hour or so. These storms are elevated, but a
pocket of weak to moderate instability upstream of this activity
(likely rooted above around 900 mb) is likely supporting the
continued hail threat as these storms continue to propagate away
from the lake. This threat should be too isolated for a WW
issuance, although a few instances of large hail remain possible
over the next 1-2 hours or so.

..Cook.. 06/15/2017

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Mesoscale Discussion 1049
NWS Storm Prediction Center Norman OK
0805 PM CDT Thu Jun 15 2017

Areas affected...parts of southwest Texas

Concerning...Severe Thunderstorm Watch 335...

Valid 160105Z - 160200Z

The severe weather threat for Severe Thunderstorm Watch 335
continues.

SUMMARY...The severe threat continues across WW 335.

DISCUSSION...Mature storms continue to migrate/propagate
southeastward across portions of west-central Texas currently, with
one supercellular structure noted across Howard County and a linear
segment across Scurry/Fisher counties. With modest low-level and
strong (2000-3000 J/kg MUCAPE) just ahead of these storms, a
continued threat for hail (perhaps significant near storms that can
exhibit updraft rotation) and severe wind gusts will continue beyond
dusk. This may necessitate eastward spatial extensions of WW 335
into portions of the Big Country and Concho Valley.

Farther southwest, higher-based activity has developed in higher
terrain of Texas and also near/just west of Midland/Odessa.
Although it is a bit late in the diurnal cycle for this activity
(and earlier activity has struggled to maintain intensity), some
potential for severe downburst winds exists given steep lapse rates
throughout the troposphere and 40-50 F surface dewpoint depressions.
A few hail stones approaching severe limits cannot be ruled out.
It is a bit uncertain whether this newer activity will persist,
however, and the overall severe threat may begin to trend downward
after dusk owing to nocturnal boundary layer cooling/stabilization.

..Cook.. 06/16/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
Mensajes: 6828
Registrado: Jue Feb 20, 2014 2:34 am
Ubicación: Río Tercero,Córdoba.
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Vie Jun 16, 2017 10:46 am

Otro día más de tiempo severo. Tremenda la seguidilla que viene teniendo esa zona. Nuevamente, viento y granizo como riesgos principales.
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Discusión.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Fri Jun 16 2017

Valid 161300Z - 171200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN
NEBRASKA ACROSS THE MISSOURI VALLEY TO PARTS OF IOWA...NORTHERN
MISSOURI AND NORTHEASTERN KANSAS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED RISK AND EXTENDING SOUTHWESTWARD ACROSS
CENTRAL/SOUTHWESTERN KANSAS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
MID-SOUTH INTO CENTRAL MISSISSIPPI...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
CENTRAL U.S. SLIGHT RISK...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SOUTHERN SLIGHT RISK AND EXTENDING TO PARTS OF FLORIDA...THE
CAROLINAS AND VIRGINIA...

...SUMMARY...
Severe thunderstorms with wind damage and hail are possible Friday
afternoon into Friday night across parts of the central Plains and
lower to middle Missouri Valley eastward into the middle to upper
Mississippi Valley. Marginally severe thunderstorms with strong
wind gusts may also impact parts of the Gulf Coast and eastern U.S.

...Synopsis...
In mid/upper levels, a belt of nearly zonal flow will extend from
the Pacific Northwest to the upper Great Lakes, and south of a
weakening cyclone now located over the MB/ON border region. A weak
but broadly cyclonic trough was located over the central/southern
Appalachians and portions of GA/AL, with several embedded/minor
vorticity maxima. Satellite and composite-reflectivity imagery
shows a well-developed MCV, located over the Ozarks between SGF-FLP,
produced by yesterday's KS/northeastern OK MCS. This feature has
been resolved remarkably well by 06Z-initialized synoptic models, as
well as more recent RAP, and hi-res/convection-allowing progs. The
MCV and accompanying shortwave trough should continue to move
southeastward across the Ozarks and much of MS through the period.

At the surface, a weak cold-frontal zone was analyzed from western
MN across northeastern and central NE to northeastern CO. This
feature will move slowly eastward today across central/eastern NE
and northwestern IA. An expansive area of outflow was evident
across much of OK, KS, MO and northwestern AR, also a relic of last
evening's severe MCS (since dissipated).

...Midwest, central Plains...
Thunderstorms are forecast to develop near the surface frontal zone
this afternoon over parts of NE and IA and move across the outlook
area, initially offering a severe-hail threat with some damaging
wind, then evolving mainly to wind into the evening hours, before
diminishing overnight.

While not ideally rich moisture as with the relatively unadulterated
Gulf air mass from the day before, it still should be sufficient to
support convective development and maintenance by md/late afternoon.
Morning surface analysis shows a very fragmented, choppy surface
isodrosothermal pattern, with dry low-level air above the surface in
SGF, OUN and TOP soundings. Forecast soundings and planar wind
fields suggest a mixture of two source regions will be involved:
1. The convectively modified low-level air from the previous day's
MCS should advect northward into this region from the Ozarks and
eastern OK initially, and linger through much of the strongest
diurnal-heating/mixing window. This should lead to strong low-level
lapse rates and well-mixed subcloud layers supporting both wind and
hail potential in early convection, followed by...
2. Late-afternoon and evening moist advection and
evapotranspiration into an area of growing thunderstorm coverage. A
western corridor of moist advection/transport already is apparent
around the MCS influence, and north of its outflow boundary, with
southerly to southwesterly 850-mb flow. Northward advection/mixing
of the shallower western fringes of the MCS air should open up a
corridor of moisture return for surface parcels as well through the
day.

Where the higher-PW air can return before sunset, across parts of
northeastern KS and perhaps southeastern NE, steep low/middle-level
lapse rates will support MLCAPE 3500-4500 J/kg, amidst 35-45 kt
effective-shear magnitudes. This will support supercell character
and a risk of significant-severe hail with any relatively
sustained/discrete modes, before upscale evolution shifts the threat
more toward wind. Ambient flow geometry aloft indicates a south of
east forward-propagational component is likely. Outlook
probabilities for wind/hail have been reoriented slightly to account
for these concepts.

...Mid-South, Mississippi Delta region...
One or more clusters of thunderstorms may evolve this afternoon
ahead of the MCV, in a very moist, strongly heated and weakly capped
air mass across parts of the Mid-South between eastern AR, western
TN and northern MS. Deep-layer lift is expected to increase on the
mesoscale over the outlook area due to the MCV's influence,
coinciding with diurnally maximized buoyancy in its path. West of a
moisture gradient located across eastern portions of the Mid-South,
surface dew points commonly in the 70s F and steep low-level lapse
rates will support preconvective MLCAPE 3000-4000 J/kg. Expect
mesoscale enhancement to the ambient northwesterly flow (therefore
to deep shear), contributing to the potential for momentum transfer,
perhaps rear-inflow-jet development, and organized upscale
development of a convective cluster for at least a few hours this
afternoon into evening across the region.

While some uncertainties remain regarding the timing and placement
of any related cold-pool evolution, enough confidence now exists in
a relative concentration of damaging and perhaps severe-magnitude
wind to introduce a 15%/slight-risk wind area. That of course will
be subject to additional refinement as mesoscale
convective/destabilization trends warrant.

...Remainder of southeastern U.S....
A variety of outflow, differential-heating, sea-breeze and
confluence boundaries are expected to contribute to the development
of scattered thunderstorms this afternoon across a broad swath from
the Potomac River region to southern AL and eastern FL -- mainly
east of the weak but extensive mid/upper trough. Deep-layer flow
over this region will be feeble, albeit difluent in upper levels,
with strong surface heating, rich moisture and weakening CINH
further supporting development. Gusts approaching severe limits and
capable of tree damage are possible, and isolated severe gusts
cannot be ruled out.

..Edwards.. 06/16/2017

Próxima actualización: 16:30z.
------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1050
NWS Storm Prediction Center Norman OK
0933 PM CDT Thu Jun 15 2017

Areas affected...Portions of the mid Missouri Valley to eastern Iowa

Concerning...Severe Thunderstorm Watch 336...

Valid 160233Z - 160330Z

The severe weather threat for Severe Thunderstorm Watch 336
continues.

SUMMARY...Clusters of strong/severe storms will continue to evolve
across Watch 336 late this evening, with some residual potential for
gusty/damaging winds and severe hail. However, overall intensity
should trend downward later tonight.

DISCUSSION...Regional radar data depict several areas of ongoing
thunderstorm activity stretching from the mid Missouri Valley
northeastward across Iowa. One rather robust core is approaching Des
Moines, with 9-km CAPPI reflectivity upwards of 65 dBZ, as of 0220Z.
Pockets of remaining steep low/mid-level lapse rates, amidst a
sufficiently sheared deep tropospheric layer, will likely maintain
some of these severe cores over the next few hours. As such, large
hail and damaging winds will remain a threat in stronger cores.
However, nocturnal cooling/increasing inhibition and a lack of
stronger large-scale ascent should foster a gradual downward trend
in the severe threat later tonight.

..Picca.. 06/16/2017

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Mesoscale Discussion 1051
NWS Storm Prediction Center Norman OK
1041 PM CDT Thu Jun 15 2017

Areas affected...Portions of eastern Oklahoma

Concerning...Severe Thunderstorm Watch 337...

Valid 160341Z - 160445Z

The severe weather threat for Severe Thunderstorm Watch 337
continues.

SUMMARY...A complex of thunderstorms will continue pushing
south/southeast this evening, with some ongoing threat of damaging
winds and perhaps marginally severe hail. The overall intensity
trend should be downward through the overnight hours, but there may
be some lingering potential for stronger gusts into the early
morning hours.

DISCUSSION...A bowing complex of thunderstorms, with a mature
trailing stratiform region, is advancing across northeast Oklahoma
late this evening. Surface observations within the trailing region
depict pressure rises of about 2-3 mb/hr, suggesting outflow will
further surge southeast through the overnight. Rich boundary-layer
moisture ahead of the line has ensured only modest nocturnal cooling
so far, such that an increase in convective inhibition has been
slow. Thus, while storm cores will likely weaken some, becoming
progressively displaced from the surging outflow, a threat of gusty
damaging winds may persist. Additionally, warm-air advection related
to the low-level jet may foster additional development along the
western/upwind flank of the complex. These cells may also pose a
threat of marginally severe hail and locally damaging winds through
the early overnight hours.

..Picca.. 06/16/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Sab Jun 17, 2017 1:50 am

Otro riesgo moderado más para esta madrugada. Viento y granizo, los riesgos más significativos.
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Discusión.
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Day 1 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0805 PM CDT Fri Jun 16 2017

Valid 170100Z - 171200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR EXTREME
SOUTHEAST NEBRASKA...SOUTHWEST IOWA...NORTHEAST KANSAS AND NORTHWEST
MISSOURI...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTHEAST NEBRASKA INTO CENTRAL IOWA...AND FROM NORTHEAST KANSAS
INTO MUCH OF NORTHWEST MISSOURI...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM KANSAS AND
MISSOURI NORTHWARD ACROSS IOWA AND INTO SOUTHWEST WISCONSIN...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL
MISSISSIPPI...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS AND UPPER MISSISSIPPI VALLEY SOUTHWARD INTO MISSISSIPPI...

...SUMMARY...
Widespread damaging wind is possible across southeast Nebraska,
Iowa, northeast Kansas and northwest Missouri this evening, along
with large hail. Isolated wind and hail also remains possible across
mainly central Mississippi, and across southern Wisconsin.

...NE...IA...KS...MO...
-- Amended to add corridor of Moderate Risk for significant winds --

A robust cluster of merged supercells continues to race
southeastward across Nebraska and western Iowa, with other cells
developing along the southwest and northeastern flanks. A very
unstable air mass exists ahead of this activity, MLCAPE in the
3000-4000 J/kg range and with steep midlevel lapse rates. This
system should persist through the evening as it moves into KS and
MO, with relatively widespread damaging winds possible. A few
significant wind gusts are possible, and have added 45% wind
probability for expected density of reports. In addition to wind,
hail is likely in the stronger cores, and, a brief tornado is also
possible given sufficiently veering winds with height and transient
supercell structures. See MCD 1061 for more information.

...Central MS...
A cluster of storms continues to shift southward across MS, with a
secondary area into southwest AL. These storms are associated with a
cool pocket aloft, which has resulted in a relatively good lapse
rate profiles supporting strong updrafts. Gusty winds will continue
to be likely, with a few near severe levels. Marginal hail is also
possible, with a gradual weakening trend with loss of heating.

...Southern WI into northern IL...
Storms are increasing across southwest WI, with apparent MCV. A warm
and unstable air mass exists all the way to Lake Michigan, thus have
expanded the Slight Risk eastward for mainly wind and marginal hail.
See MCD 1063 for more information.

..Jewell.. 06/17/2017

Está vigente hasta las 06:00z.
---------------------------------------------------------------
Watchs vigentes.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 341
NWS Storm Prediction Center Norman OK
745 PM CDT Fri Jun 16 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
South-central Iowa
Northeast and eastern Kansas
Western and Northern Missouri

* Effective this Friday night and Saturday morning from 745 PM
until 400 AM CDT.

* Primary threats include...
Widespread damaging winds likely with isolated significant gusts
to 85 mph possible
Scattered large hail likely with isolated very large hail events
to 2 inches in diameter possible
A tornado or two possible

SUMMARY...An intense linear convective system, responsible for a
measured 88 mph wind gust at the Omaha-Valley National Weather
Service office, will likely continue to expand and accelerate
southeastward this evening as it races into northeast/eastern Kansas
and western/northern Missouri, potentially including the Kansas City
Metro area, as well as parts of south-central Iowa. Widespread wind
damage seems likely this evening into the overnight in these areas,
along with some embedded tornado risk in addition to isolated
instances of large hail.

The severe thunderstorm watch area is approximately along and 75
statute miles east and west of a line from 50 miles north northeast
of Des Moines IA to 50 miles south southwest of Olathe KS. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 338...WW 339...WW 340...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 75 knots. A
few cumulonimbi with maximum tops to 650. Mean storm motion vector
30040.

...Guyer

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 342
NWS Storm Prediction Center Norman OK
1025 PM CDT Fri Jun 16 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Eastern Iowa
Northern Illinois
Southern Wisconsin
Lake Michigan

* Effective this Friday night and Saturday morning from 1025 PM
until 500 AM CDT.

* Primary threats include...
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Isolated damaging wind gusts to 70 mph possible

SUMMARY...A weak mid-level disturbance or two combined with
residually steep lapse rates and moderate deep-layer shear will
continue to pose at least an episodic severe risk mainly in the form
of large hail and locally damaging winds as storms spread eastward
late this evening into the overnight.

The severe thunderstorm watch area is approximately along and 60
statute miles east and west of a line from 30 miles northwest of
Milwaukee WI to 45 miles west southwest of Moline IL. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 341...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
28025.

...Guyer

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Últimas discusiones a mesoescala.
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Mesoscale Discussion 1052
NWS Storm Prediction Center Norman OK
1205 PM CDT Fri Jun 16 2017

Areas affected...Much of MS...far western AL...eastern LA...eastern
AR

Concerning...Severe potential...Watch possible

Valid 161705Z - 161930Z

Probability of Watch Issuance...60 percent

SUMMARY...The risk for severe thunderstorms is increasing, and
Severe Thunderstorm Watch issuance is possible within the next
couple of hours -- across portions of the area.

DISCUSSION...The air mass is strongly destabilizing across parts of
the lower MS Valley, ahead and south of a well-defined and
long-lived MCV crossing eastern AR. With surface temperatures having
already warmed well into the 80s amid dewpoints in the lower/middle
70s, buoyancy has become very strong across the region, with SBCAPE
of 3500-4500 J/kg and minimal MLCINH across a large part of the
area. Banded/coiling cumulus fields ahead of the MCV are becoming
increasingly agitated, where ascent is maximized, and storm
formation will likely occur soon across the Mid-South. Further
strengthening of differential heating / baroclinicity along
MCV-related remnant cloud shields will also encourage storm
development, along with deepening boundary-layer circulations
elsewhere across the uncapped/moist boundary layer.

Upward convective-scale accelerations will be bolstered by an influx
of steep lapse rates aloft from the northwest, with 12Z soundings at
Little Rock and Shreveport sampling 8-9 C/km midlevel lapse rates.
This will support the risk for severe hail, especially during
initial stages of convective development. Subsequently,
strengthening downdrafts -- aided by DCAPE of 1000-1400 J/kg -- will
support increasing damaging-wind potential. If sufficiently dense
convective coverage and cold-pool amalgamation were to breed at
least loose upscale convective growth -- spreading to the
southeast/south -- then a more substantial damaging-wind risk could
evolve. The absence of stronger/more widespread deep ascent could
mitigate this potential. However, enhanced midlevel flow and deep
shear peripheral to the MCV -- e.g. 30-40 kt midlevel winds
indicated by VAD wind profiles -- suggest that convection may
exhibit somewhat organized character this afternoon into the early
evening. This would especially be the case with westward extent
across the discussion area.

..Cohen/Hart.. 06/16/2017

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Mesoscale Discussion 1053
NWS Storm Prediction Center Norman OK
1227 PM CDT Fri Jun 16 2017

Areas affected...Portions of the Carolinas and southern VA

Concerning...Severe potential...Watch unlikely

Valid 161727Z - 162000Z

Probability of Watch Issuance...5 percent

SUMMARY...Strong-thunderstorm potential will develop during the next
couple of hours and continue into the early evening. Isolated
damaging wind gusts could occur, though lacking convective
organization with anticipated limited severe coverage should
preclude Watch issuance.

DISCUSSION...Amid a broad area of surface heating and PW values of
1.6-2.0 inches with minimal capping, an increase in the number and
intensity of thunderstorms will occur through the afternoon. Forcing
for ascent will emanate from diurnally enhanced orographic
circulations over the Appalachians, weak ascent peripheral to a
couple of weak midlevel cyclonic perturbations crossing the area
(one along the SC coast and one crossing the northeast Gulf),
sea-breeze boundaries over the coastal plain, and deepening
boundary-layer circulations across the region.

With 1500-2500 J/kg of MLCAPE in place, a few robust convective
cores may evolve, with the substantive deep moisture bolstering
precipitation-loading processes and the potential for strong
downdrafts. Localized instance of loosely organized multicell
convective clusters could occur where cold pools amalgamate, given a
slight enhancement to the flow aloft (15 kt at 500 mb) peripheral to
the cyclonic perturbations. The most intense convection may produce
isolated damaging wind gusts as it spreads across the region into
the early evening hours -- before nocturnal gains in boundary-layer
static stability occur. However, convection should mostly be lacking
organized character, and midlevel lapse rates are quite modest. As
such, a more substantial severe risk is not presently anticipated.

..Cohen/Hart.. 06/16/2017

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Mesoscale Discussion 1054
NWS Storm Prediction Center Norman OK
1245 PM CDT Fri Jun 16 2017

Areas affected...Portions of southeast MO...southern IL...western
KY...western TN...northeast AR

Concerning...Severe potential...Watch unlikely

Valid 161745Z - 162015Z

Probability of Watch Issuance...20 percent

SUMMARY...There will exist the potential for isolated severe
thunderstorms through the afternoon across parts of the lower Ohio
Valley region and Mid-South. While environmental and convective
trends will continue to be monitored, the issuance of a Watch is
presently unlikely.

DISCUSSION...Ascent across the northeastern quadrant of an MCV
crossing eastern AR, and along the edges of MCV-related multi-
layered cloud canopies where differential-heating-induced
baroclinicity is being diurnally enhanced, will continue to foster
an increase in convective coverage across the area. Inflow buoyancy
for this activity is strong (e.g., 2000-3000 J/kg of MLCAPE), owing
to strong surface heating amid dewpoints in the lower/middle 70s.
This will likely support robust updrafts capable of isolated severe
hail/wind, with local convective clustering / cold-pool amalgamation
focusing damaging-wind potential.

Eastward propagation of this activity will be favored by
preferential development of regenerative convection into the higher
theta-e air east of the ongoing convection. However, deep shear is
quite weak across the region, with effective shear magnitudes
generally below 25 kt. This should tend to limit the severe
coverage. Furthermore, as storms approach a minimum in deep moisture
with additional eastward extent across the lower Ohio Valley, they
may tend to weaken owing to dry-air entrainment and eventual
ingestion of weaker buoyancy as boundary-layer moisture mixes out.

..Cohen/Hart.. 06/16/2017

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Mesoscale Discussion 1055
NWS Storm Prediction Center Norman OK
0141 PM CDT Fri Jun 16 2017

Areas affected...Central/eastern NE...Northern KS...Western IA

Concerning...Severe potential...Watch likely

Valid 161841Z - 162015Z

Probability of Watch Issuance...80 percent

SUMMARY...Severe thunderstorm development is possible within the
next 1-2 hours, with an increase in the coverage of the threat later
this afternoon. The threat of damaging wind and very large hail will
likely result in the need for watch issuance.

DISCUSSION...At 1830Z, towering cumulus is developing across
southwest NE in the vicinity of a dryline, with additional attempts
at surface-based cumulus development further north near a surface
low across north-central NE. Continued strong heating and the
glancing influence of a vort max moving across the Dakotas will
eventually result in the development of scattered thunderstorms from
southwest into central/north-central NE. Initial development will
likely remain somewhat isolated and occur within a hot and
deeply-mixed environment, with sufficient effective shear in place
to support organized storm structures including supercells.

Further east, rich low-level moisture is in the process of returning
into portions of eastern NE in the wake of last night's MCS. Strong
to extreme buoyancy will be in place across this region later this
afternoon, and as thunderstorms move into this environment, a few
intense supercells capable of very large hail, damaging winds, and
perhaps a tornado or two will be possible. Some upscale growth is
possible late this afternoon (becoming more likely toward evening),
which would result in the development of an enhanced wind damage
threat expanding into portions of northeast KS, northwest MO, and
western IA. One or more watches will be required to cover this
threat later this afternoon into this evening.

..Dean/Hart.. 06/16/2017

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Mesoscale Discussion 1056
NWS Storm Prediction Center Norman OK
0225 PM CDT Fri Jun 16 2017

Areas affected...Central/eastern WI...Upper Peninsula of MI

Concerning...Severe potential...Watch unlikely

Valid 161925Z - 162130Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated instances of hail and damaging wind are possible
this afternoon. Watch issuance is not currently anticipated.

DISCUSSION...Thunderstorms are gradually increasing in coverage and
intensity across portions of WI into the U.P. of MI. This region is
within the influence of a well-defined upper trough centered over
western Ontario, with multiple embedded vort maxes noted within the
belt of westerly flow south of the trough. With breaks in the clouds
noted across southern and eastern WI into portions of the U.P., some
additional destabilization is possible over the next 1-2 hours as
convection continues to increase, with MLCAPE of 750-2000 J/kg
(increasing with southward extent) developing across the region.
Moderate westerly flow aloft will result in sufficient effective
shear (30-35 kts) for some storm organization, though the generally
ill-defined surface pattern and lack of any substantial low-level
foci for convection should tend to limit storm coverage and
intensity to some extent. Relatively steep mid- and low-level lapse
rates will support a threat of isolated hail and damaging wind with
the strongest cores, though at this time the threat appears too
marginal for watch issuance.

..Dean/Hart.. 06/16/2017

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Mesoscale Discussion 1057
NWS Storm Prediction Center Norman OK
0329 PM CDT Fri Jun 16 2017

Areas affected...Southern MN...Northern IA...Southwest WI

Concerning...Severe potential...Watch likely

Valid 162029Z - 162200Z

Probability of Watch Issuance...80 percent

SUMMARY...The severe thunderstorm threat is expected to increase
late this afternoon, with a primary threat of large hail and
damaging wind. Watch issuance is likely within the next 30 minutes.

DISCUSSION...A recent increase in intensity has been noted within a
region of previously weak midlevel convection across southern MN and
far northern IA, suggesting that storms have become rooted closer to
the surface. Substantial heating ahead of this activity has weakened
MLCINH, and a continued increase in coverage and intensity is
possible into late afternoon, aided by large-scale ascent ahead of a
vort max moving through the Dakotas and modest low-level convergence
near a surface boundary across southeast MN/western WI.

While low-level moisture is rather limited at this time across the
region, some increase is possible later this afternoon into early
this evening. Even with the modest moisture, strong heating to near
90F in some areas has resulted in moderate destabilization, with
MLCAPE increasing into the 1000-2000 J/kg range across the area.
Moderate westerly midlevel flow is resulting in effective shear of
35-45 kts for surface-based updrafts, which is sufficient for storm
organization. With convection expected to remain largely discrete in
the short term, a supercell or two is possible with a threat of
large hail and locally damaging wind. With time, some upscale growth
is possible as cold pool generation occurs, resulting in an
increasing damaging wind threat with eastward extent into the early
evening.

..Dean/Hart.. 06/16/2017

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Mesoscale Discussion 1058
NWS Storm Prediction Center Norman OK
0340 PM CDT Fri Jun 16 2017

Areas affected...MS...western AL...eastern LA...eastern
AR...southwest TN

Concerning...Severe Thunderstorm Watch 338...

Valid 162040Z - 162245Z

The severe weather threat for Severe Thunderstorm Watch 338
continues.

SUMMARY...The risk for severe storms continues across Watch 338.

DISCUSSION...Convective coverage and intensity are increasing across
northwest and north-central MS, where sufficient density and areal
coverage of convective plumes are fostering cold pool amalgamation.
At least loosely organized clusters may evolve from this activity
and spread south-southeastward into a boundary layer characterized
by high theta-e. The presence of 20-30 kt of 4-6-km above-ground
flow indicated by the Jackson VAD wind profile supports this notion
of modest convective organization. Additional more isolated to
widely scattered convection is developing farther south, as
boundary-layer circulations have strengthened amid minimal MLCINH.

As the aforementioned convection ingests inflow characterized by
SBCAPE of 3000-5000 J/kg -- aided by 7.5-8.5 C/km midlevel lapse
rates overlying lower/middle 70s surface dewpoints -- convection
should continue intensifying. With the potential for more
cluster-mode convection becoming apparent, damaging wind gusts
should be the primary hazard -- particularly given DCAPE over 1500
J/kg in some areas amid the aforementioned large SBCAPE. Severe hail
may also accompany the strongest incipient updrafts.

There may be a tendency for the primary corridor of greatest
severe-wind risk to extend through parts of central MS into the late
afternoon hours, especially if upscale convective growth were to
continue. Later this afternoon into the evening, this potential
cluster of storms -- and/or additional preceding developing
storms -- could spread south/southeast of the Watch with a severe
risk. If the risk for more organized convection with severe
potential were to become apparent in these areas, some consideration
could be given to additional Watch issuance.

..Cohen.. 06/16/2017

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Mesoscale Discussion 1059
NWS Storm Prediction Center Norman OK
0353 PM CDT Fri Jun 16 2017

Areas affected...Northern lower MI

Concerning...Severe potential...Watch unlikely

Valid 162053Z - 162230Z

Probability of Watch Issuance...5 percent

SUMMARY...Scattered strong thunderstorms will continue this
afternoon, with some threat for isolated hail and/or locally
damaging wind.

DISCUSSION...Thunderstorms have recently increased in coverage and
intensity across northern lower MI. Storms near Alpena have
exhibited weak rotation, and some threat for hail and localized
damaging wind will exist with this activity as it approaches Lake
Huron over the next 1-2 hours. Additional development is underway
further to the southwest, and with MLCAPE of 500-1000 J/kg and
effective shear of around 30 kts, some weak organization is possible
with a corresponding threat of localized hail and damaging wind with
any additional development. The threat is expected to be too limited
in spatiotemporal extent for watch issuance.

..Dean/Hart.. 06/16/2017

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Mesoscale Discussion 1060
NWS Storm Prediction Center Norman OK
0544 PM CDT Fri Jun 16 2017

Areas affected...Portions of west Texas

Concerning...Severe potential...Watch unlikely

Valid 162244Z - 162345Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated storms may be capable of severe hail and
strong/gusty winds this evening. However, they should remain limited
in both space and time, precluding watch issuance.

DISCUSSION...Isolated convection has developed across far west Texas
late this afternoon. Large-scale forcing for ascent is weak, and
mid-level temperatures are quite warm; however, orographic and
dryline circulations have primed the environment sufficiently for
isolated vigorous updrafts. Moist southeasterly boundary-layer flow
veers to west/northwest mid/upper flow, promoting effective shear
around 40-50 kt -- favorable for mid-level rotation. As such, any
sustained/deep convection will be capable of severe hail and
strong/gusty winds. However, due to the large-scale environment
being unfavorable for more widespread coverage, watch issuance is
not anticipated.

..Picca/Guyer.. 06/16/2017

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Mesoscale Discussion 1061
NWS Storm Prediction Center Norman OK
0616 PM CDT Fri Jun 16 2017

Areas affected...Portions of the mid Missouri Valley

Concerning...Severe Thunderstorm Watch 339...

Valid 162316Z - 170115Z

The severe weather threat for Severe Thunderstorm Watch 339
continues.

SUMMARY...A line of significant severe thunderstorms will move
through the Omaha metro area over the next couple of hours. Damaging
wind gusts (a few of which could be 75+ mph), large hail, and
tornadoes will remain possible.

DISCUSSION...Regional radar data depict a cluster of
high-precipitation supercells across eastern Nebraska early this
evening. These storms have already produced an array of severe
weather, including a gust to 74 mph at Norfolk, NE as a stout
mesocyclone passed the site. As of 2300Z, KOAX data exhibited at
least two strong rear-flank downdraft surges within this line of
embedded supercells. These surges should support a continued upscale
growth of these cells into a bowing complex that accelerates rapidly
southeast towards Omaha, likely reaching the metro area around
00-01Z (7-8pm CDT).

A 21Z OAX observed sounding sampled a thermodynamic profile quite
favorable for damaging wind gusts. Moreover, low-level and
deep-layer shear suggest very large hail and tornadoes will remain
possible in any discrete or embedded supercellular elements.
Therefore, all severe hazards remain possible with these storms, and
damaging gusts (some of which could be over 75 mph) appear likely
in/around the Omaha and Lincoln areas within the next 1-2 hours.
Additionally, downstream watch issuance in Iowa/Missouri will likely
be needed within the next two hours.

..Picca.. 06/16/2017

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Mesoscale Discussion 1062
NWS Storm Prediction Center Norman OK
0619 PM CDT Fri Jun 16 2017

Areas affected...much of mississippi...western
Alabama...northeastern louisiana...and far southeastern arkansas

Concerning...Severe Thunderstorm Watch 338...

Valid 162319Z - 170015Z

The severe weather threat for Severe Thunderstorm Watch 338
continues.

SUMMARY...The severe threat continues across central/southern
portions of WW 338, and a damaging wind threat may eventually impact
western Alabama over the next hour or so.

DISCUSSION...A couple of linear, forward propagating thunderstorm
segments have evolved over WW 338 - 1) moving southward across the
Mississippi Delta toward west-central Mississippi and 2) another
migrating slowly southeastward across east-central Mississippi.
Both of these complexes are capable of localized damaging wind gusts
and perhaps marginally severe hail owing to moderate instability
(3000-4000 J/kg MUCAPE) within the pre-convective airmass ahead of
the storms. Deep shear is a bit stronger with western extent, which
may partially explain the faster southward propagation with the
western Mississippi segment.

Storms will likely begin to impact areas just east of WW 338 over
the next 30 minutes or so, with a localized damaging wind threat
continuing with this activity. The probability of a new downstream
watch is relatively low, however, as this threat should be fairly
confined to a small part of far western Alabama. Damaging wind
gusts and hail are also possible along and just east of the
Mississippi River through at least dark. Farther north, overturning
and attendant low-level stabilization has lessened the severe threat
such that portions of WW 338 may be cancelled early - particularly
in northeastern Mississippi.

..Cook.. 06/16/2017

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Mesoscale Discussion 1063
NWS Storm Prediction Center Norman OK
0656 PM CDT Fri Jun 16 2017

Areas affected...Portions of the upper Mississippi Valley

Concerning...Severe Thunderstorm Watch 340...

Valid 162356Z - 170100Z

The severe weather threat for Severe Thunderstorm Watch 340
continues.

SUMMARY...A few strong/severe storms may advance outside the
northern bounds of Watch 340 this evening. Currently, downstream
watch issuance does not appear imminent, but convective trends will
be monitored for an uptick in intensity near southern/eastern
portions of the watch this evening.

DISCUSSION...A pair of left-moving cells are advancing towards the
northern edge of Watch 340 this evening. Forecast sounding and
regional VWP data indicate relatively straight mid-level hodographs,
suggesting some maintenance of these cells and a persisting threat
of strong/gusty winds and near-severe hail. However, over time,
decreasing buoyancy with northward extent should result in a
downward intensity trend. Farther southwest, a large precipitation
shield has overspread much of northern Iowa, casting some doubt upon
convective intensification/re-development here. Nonetheless, a warm
and moist boundary layer exists to the south of a trailing outflow
boundary stretching across northern Iowa. Within this corridor,
high-res guidance indicates strong/severe convection may develop
later this evening, with an attendant threat of damaging winds and
large hail. While new watch issuance does not appear imminent, one
could be necessary later this evening.

..Picca.. 06/16/2017

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Mesoscale Discussion 1064
NWS Storm Prediction Center Norman OK
0927 PM CDT Fri Jun 16 2017

Areas affected...Portions of the mid Missouri Valley

Concerning...Severe Thunderstorm Watch 339...341...

Valid 170227Z - 170430Z

The severe weather threat for Severe Thunderstorm Watch 339, 341
continues.

SUMMARY...A line of significant severe thunderstorms will continue
accelerating south/southeast this evening, maintaining the potential
for a swath of damaging winds (some gusts over 80 mph), large hail,
and perhaps a tornado or two. This line will likely reach the Kansas
City metro after 11pm CDT.

DISCUSSION...A mature complex of powerful thunderstorms is racing
southeast this evening, into an axis of strong instability
characterized by MLCAPE values upwards of 4500 J/kg. Indeed, the 00Z
TOP sounding sampled an excessively wide mid-level buoyancy profile
amidst a favorable deep-layer wind profile veering with height. Rich
boundary-layer moisture will temper nocturnal cooling such that this
high buoyancy (with little inhibition) will be maintained for the
next few hours. As such, these significant severe storms are
expected to maintain their intensity as they continue pushing
southeast. Furthermore, a strengthening low-level jet will likely
enhance both downwind and upwind propagation this evening,
maintaining the threat of powerful damaging wind gusts. Upstream
observations confirm this severe potential, with Lincoln, NE
reporting a 76kt (87mph) gust at 0137Z (837pm CDT). Significant
severe wind gusts (upwards of 80mph), large hail, and a tornado or
two will remain possible with this line as it advances towards the
Kansas City metro area over the next two hours.

..Picca.. 06/17/2017

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Mesoscale Discussion 1065
NWS Storm Prediction Center Norman OK
1114 PM CDT Fri Jun 16 2017

Areas affected...Areas from northeast Kansas to the mid Mississippi
Valley

Concerning...Severe Thunderstorm Watch 341...

Valid 170414Z - 170545Z

The severe weather threat for Severe Thunderstorm Watch 341
continues.

SUMMARY...A powerful mesoscale convective system is racing southeast
this evening, while maintaining a threat of numerous damaging gusts,
wind-driven hail, and a tornado or two. One or more downstream
watches will likely be needed over the next several hours.

DISCUSSION...An expanding line of severe thunderstorms is dropping
south/southeast across the mid Missouri Valley this evening, aided
by strong storm-relative inflow in the lowest approximately 2 km,
based on recent EAX VWP data. This convective system has expanded in
length recently, as the downwind-propagating component has
accelerated eastward across northern Missouri, while very robust
upwind propagation (with multiple embedded supercells) has advanced
into northern Kansas. Across this line, a continued threat of
numerous severe/damaging gusts (a few of which will likely be 75-80+
mph) will exist. Indeed, St. Joseph MO gusted to 66kt (76mph) at
0347Z (1047pm CDT). While surface cooling and drier boundary-layer
conditions have brought about a quicker increase in inhibition
across eastern Missouri, steep lapse rates and forced ascent along
outflow could maintain a threat of damaging winds beyond the eastern
bound of the watch. Therefore, a new downstream watch may be
considered.

Farther west, the combination of embedded organized updrafts, ample
mid-level buoyancy, and strongly forced low-level ascent should be
sufficient to overcome inhibition and spread the severe threat to
the southern edge of the watch later tonight. Therefore, downstream
watch issuance across southern Missouri and far southeast Kansas
will likely be needed within the next 1-2 hours.

..Picca.. 06/17/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Sab Jun 17, 2017 2:14 am

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 343
NWS Storm Prediction Center Norman OK
1135 PM CDT Fri Jun 16 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Eastern Missouri

* Effective this Friday night and Saturday morning from 1135 PM
until 500 AM CDT.

* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...A fast-moving line of convection will continue to steadily
move east-southeastward into and across east-central Missouri during
the overnight hours. Isolated wind damage will be possible along
with the possibility of a few instances of severe hail.

The severe thunderstorm watch area is approximately along and 30
statute miles east and west of a line from 30 miles northwest of
Quincy IL to 20 miles south of Jefferson City MO. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 341...WW 342...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
30035.

...Guyer

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 344
NWS Storm Prediction Center Norman OK
1210 AM CDT Sat Jun 17 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Southeast Kansas
Southern Missouri

* Effective this Saturday morning from 1210 AM until 700 AM CDT.

* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Isolated large hail events to 1.5 inches in diameter possible
A tornado or two possible

SUMMARY...Although an intense convective line across northeast
Kansas and northern Missouri may eventually weaken, a strong to
severe-caliber line of storms is expected to move into additional
parts of central and southern Missouri and possibly southeast Kansas
overnight. Damaging wind gusts will be main concern.

The severe thunderstorm watch area is approximately along and 40
statute miles north and south of a line from 10 miles southeast of
Vichy MO to 15 miles south of Chanute KS. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU4).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 341...WW 342...WW 343...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
30035.

...Guyer
Dome, dome, dome..The life is a dome

marleygaletfede
Mensajes: 1929
Registrado: Lun Feb 20, 2012 10:13 pm
Ubicación: La Costa, Buenos Aires

Re: Seguimiento general en EEUU

Mensajepor marleygaletfede » Sab Jun 17, 2017 2:24 pm

Se imaginan una semana asi por aca? Ja ja.... soñar no cuesta nada

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Sab Jun 17, 2017 4:39 pm

Oooootra vez más, tiempo severo por allá. Tremenda la seguidilla. Viento y granizo, nuevamente los riesgos significativos.
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Discusión.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1137 AM CDT Sat Jun 17 2017

Valid 171630Z - 181200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER EASTERN
KANSAS ACROSS NORTHERN/CENTRAL MISSOURI INTO CENTRAL ILLINOIS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM
CENTRAL/EASTERN KANSAS AND EASTERN OKLAHOMA ACROSS THE MIDDLE
MISSISSIPPI VALLEY INTO INDIANA AND SOUTHERN LOWER MICHIGAN...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS TOWARD THE SOUTHERN GREAT LAKES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE EASTERN
DAKOTAS INTO MINNESOTA...

...SUMMARY...
Severe thunderstorms are expected late this afternoon into tonight,
mainly from the central Plains across the middle Mississippi Valley
into southern Lower Michigan, with damaging gusts and hail likely.
Isolated severe thunderstorms also are possible this afternoon over
parts of the Dakotas and Minnesota.

...Central Plains across the middle Mississippi Valley into southern
Lower Michigan...
Prior convection from yesterday/last night has modified the
environment across this region with slightly lower surface dew
points evident this morning. However, thinning clouds across much
of this corridor from Kansas into Illinois will promote stronger
diabatic heating to occur this afternoon, and some recovery of
low-level moisture with increasing surface dew points from Missouri
eastward is likely this afternoon. 12Z soundings over the Plains
maintain steep lapse rates that will spread eastward toward the
Mississippi Valley this afternoon, contributing to moderate/strong
instability with MLCAPE ranging from 3500-4000 J/kg over eastern
Kansas to 1500-2000 J/kg over in the Indiana/Michigan region. The
presence of the EML is also likely to delay convective initiation
from Kansas into Missouri until the late afternoon/evening.

As a short wave trough over the northern high plains moves
southeastward in response to stronger west-northwest winds in the
mid/upper levels, flow over the central plains and mid-Mississippi
Valley will strengthen enhancing deep layer shear over the region.
Model guidance is reasonably consistent indicating that storms are
likely to develop near an advancing cold front, initially over
southeast Iowa/northern Missouri, then gradually developing westward
along/near the front into parts of central/eastern Kansas late this
afternoon and evening. The strong instability coupled with 35-45 kt
deep layer shear will support development of multiple clusters/lines
of severe storms capable of producing large hail with significant
hail possible, especially during the early stages of storm
maturation, and damaging winds as activity moves eastward and
southeastward through the evening hours. There are indications that
some bowing line segment will develop which may promote significant
wind gusts mainly during the evening hours.

Farther west over the central High Plains, model consensus indicates
convective coverage will be more isolated with a few storms
developing from extreme northeast Colorado area moving southeastward
into parts of western Kansas. A deep mixed layer/steep lapse rates
will be favorable for strong/severe wind gusts and possible hail
late this afternoon and evening.

...Eastern Oklahoma into Eastern Texas and Southwest Louisiana...
A small complex of strong/severe storms continues to move southward
into southeast Oklahoma. The air mass in advance of the activity is
continuing to warm/destabilize, although a capping inversion on the
12Z SHV sounding associated within EML provides some uncertainty
regarding the persistence of the system into the afternoon. A low
probability of severe storms has been added into eastern Texas to
account for this scenario, with potential for additional strong
storms to develop as far south as southwest Louisiana.

...Eastern Dakotas, Minnesota...
Behind the surface cold front, widely scattered to scattered
thunderstorms are expected to develop this afternoon with the risk
for isolated severe hail and gusts. This potential will be
supported by the strengthening large-scale ascent and deep shear
associated with the approaching northern-stream trough in mid/upper
levels, overlying diabatically minimized afternoon MLCINH and weak
convergence near a surface trough. Though conditions will be
seasonally cool at the surface, with temps in the 60s and dew points
50s F, this still will support MLCAPE 500-1000 J/kg, with some areas
of effective-shear magnitudes reaching 30-35 kt. This threat should
abate quickly after dark as the boundary layer stabilizes, due to a
combination of cold advection and diabatic cooling.

..Weiss/Cohen.. 06/17/2017

Próxima actualización: 20:00z.
----------------------------------------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1066
NWS Storm Prediction Center Norman OK
0135 AM CDT Sat Jun 17 2017

Areas affected...Southern WI...eastern IA...and northwest and
northern IL

Concerning...Severe Thunderstorm Watch 342...

Valid 170635Z - 170830Z

The severe weather threat for Severe Thunderstorm Watch 342
continues.

SUMMARY...Although a locally strong wind gust cannot be ruled out,
the overall severe-weather threat should continue to diminish during
the overnight. Parts or much of WW 342 could be canceled prior to
10Z (5 AM).

DISCUSSION...Radar trends (including MRMS MESH and 7- and 9-km
CAPPI) indicated overall weakening storm intensities with the
ongoing convection across southern WI, much of eastern IA into
western and northern portions of IL during the last 1-2 hours. This
weakening trend was further confirmed by decreasing lightning
coverage within this activity. The combination of convective
overturning of the environment and strengthening surface-based
inhibition through the night provides limited ability for stronger
storms to develop as this area of showers and embedded thunderstorms
spreads to the east-southeast. Veering 850-mb winds will also limit
convergence, with last several runs of the HRRR suggesting the
ongoing weakening trend in storm intensity and coverage will persist
as showers and some storms advance farther east-southeast into
northern IL during the night and early morning.

..Peters.. 06/17/2017

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Mesoscale Discussion 1067
NWS Storm Prediction Center Norman OK
0258 AM CDT Sat Jun 17 2017

Areas affected...Eastern KS/western...central...and northeast
Missouri

Concerning...Severe Thunderstorm Watch 341...343...344...

Valid 170758Z - 171000Z

The severe weather threat for Severe Thunderstorm Watch 341, 343,
344 continues.

SUMMARY...The greatest severe-weather threat (damaging winds and
hail) is expected to be across eastern KS and west-central to
southwest MO through early this morning. KS counties located along
the western part of WW 344 may need to be added, while parts of WW
341 is extended in time, as new storms continue to form across the
west/northwest periphery of the ongoing convective complex and
spread to the southeast.

Meanwhile, the severe-weather threat should continue to weaken
across WW 343.

DISCUSSION......WW 341 and WW 344...
Trends in IR satellite and radar imagery indicated the western and
southwest portions of the large KS/MO/IA/IL mesoscale-convective
complex across eastern KS and western and southwest portions of MO
should pose the greatest severe-weather threat through early this
morning. Coldest cloud tops and the most persistent, intense storms
per MRMS data extended from southeast Marshall/northern Pottawatomie
Counties KS to Franklin/northern Anderson and Miami Counties KS to
Henry/northwest Benton/southwest Pettis Counties MO. A southwest
40-kt low-level jet extending into the southwest portion of the MCC
from OK will sustain an inflow of very strong instability (2500-4000
J/kg of most-unstable CAPE per objective analyses and 06Z Lamont, OK
sounding). This combined with vertically veering wind profile (per
06Z LMN sounding), with effective bulk shear exceeding 45-50 kt,
will maintain strong updrafts. In addition to locally damaging
winds remaining possible, a plume of steep midlevel lapse rates (7-8
C/km per 06Z LMN sounding) extending from southern KS to southern MO
will favor a large-hail threat along the west/southwest part of the
MCC. This latter threat could result in additional counties in
east-central/southeast KS being added to WW 344.

...WW 343...
Weakening trends in MRMS CAPPI (5-9 km) and MESH data combined with
a great reduction in lightning data across northeast MO suggest the
overall severe-weather threat should continue wane across WW 343
during the overnight. Veering 850-mb winds further weakening
low-level convergence across this region support this scenario, and
this watch could be canceled prior to 10Z (5 AM).

..Peters.. 06/17/2017

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Mesoscale Discussion 1068
NWS Storm Prediction Center Norman OK
0531 AM CDT Sat Jun 17 2017

Areas affected...Southeast KS and southwest MO into far northeast OK
and northwest AR

Concerning...Severe Thunderstorm Watch 344...

Valid 171031Z - 171200Z

The severe weather threat for Severe Thunderstorm Watch 344
continues.

SUMMARY...Severe-weather threat will be the greatest across the
western portion of WW 344 (in southeast KS and southwest MO) through
early this morning. Large hail and locally damaging wind gusts will
be the primary severe risks. Although some severe hail and/or
stronger/damaging wind gusts could affect part of far northeast OK
and northwest AR, the expected spatial coverage is expected to
remain too small to warrant a new WW issuance, at this time.

DISCUSSION...The leading band of storms in southwest MO exited the
southern extent of WW 344 just before 10Z and is moving to the
south-southeast at close to 40 kt. Although this forward speed
would tend to support locally strong/damaging wind gusts, the
strength of surface-based inhibition and weak surface-3-km lapse
rates should continue to limit most stronger/damaging wind gusts
from reaching the surface as activity moves into northwest AR.

Meanwhile, a threat remains for mainly large hail, some exceeding 2
inches in diameter, across southeast KS into far southwest MO
through early this morning. Trends in MRMS MESH data and CAPPI (5-9
km) through 1005Z indicated strong, sustained updrafts in southeast
KS (Allen and Crawford Counties), while upstream storms moving
southeast into and through Douglas County KS were restrengthening.
Trends in IR satellite imagery indicated an overall shrinking in
size of the larger thunderstorm complex in eastern KS and MO.
However, a 35-40-kt west-southwesterly low-level jet extending from
OK into the southwest periphery of this convection is expected to
sustain thunderstorm development through early this morning, with an
influx of strong instability. This combined with effective bulk
shear around 50 kt and steep midlevel lapse rates will support
strong, sustained updrafts with large hail the primary threat.

..Peters.. 06/17/2017

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Mesoscale Discussion 1069
NWS Storm Prediction Center Norman OK
0928 AM CDT Sat Jun 17 2017

Areas affected...eastern Oklahoma...western Arkansas...and far
northeast Texas

Concerning...Severe potential...Watch possible

Valid 171428Z - 171630Z

Probability of Watch Issuance...40 percent

SUMMARY...A small cluster of strong/locally severe storms will
continue moving south across the eastern Oklahoma vicinity,
accompanied by local risk for marginally severe hail/wind. Though
at this time convection is expected to remain limited in coverage,
and eventually decreasing in intensity over the 1-2 hours, WW may be
required if storms persist/increase in coverage and intensity.

DISCUSSION...Latest radar loop continues to show a small cluster of
vigorous convection moving southward across parts of eastern
Oklahoma, within an axis of low- to mid-70s dewpoints and associated
maximum in mixed-layer CAPE (around 2000 J/kg). Area RAOBs and VWPs
show rather modest -- though veering -- flow with height, along with
a slowly diminishing west-southwesterly low-level jet.

A plume of very warm/dry air near 850 mb is being advected slowly
eastward, and thus capping will limit any potential for westward
expansion of storms along the southwestward-moving outflow.
Additionally, the morning SHV RAOB also shows substantial capping,
suggesting that southward progression of the convection will also
likely remain limited. As such, a rather small spatial area for
continuation of the ongoing convection is suggested. Additionally,
with relatively modest flow aloft to limit overall organization
potential, ongoing severe risk is expected to remain limited in
magnitude, and contained areally and temporally. Still, should
diurnal heating south of the convection in a relatively cloud-free
zone over southeast Oklahoma allow storms to persist, and increase
somewhat in coverage, WW would be considered.

..Goss/Weiss.. 06/17/2017

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Mesoscale Discussion 1070
NWS Storm Prediction Center Norman OK
0121 PM CDT Sat Jun 17 2017

Areas affected...Portions of MS/LA

Concerning...Severe potential...Watch unlikely

Valid 171821Z - 172045Z

Probability of Watch Issuance...5 percent

SUMMARY...The potential for isolated severe hail/wind may accompany
thunderstorms developing this afternoon and continuing into the
evening hours. Watch issuance will not be needed.

DISCUSSION...Air-mass recovery over the vicinity of the western
reaches of modifying convective outflow, deposited by
yesterday's/last night's MCS clusters, is ongoing owing to ample
insolation. Meanwhile, west-southwesterly low-level flow is
encouraging isentropic ascent atop the residual outflow, with weak
capping across the region aided by ample diabatic surface-layer
heating amid dewpoints in the middle 70s. This will continue to
support an increase in the number and intensity of thunderstorms
across the region during the next few hours, with storms forecast to
move across the region into the evening.

Given moist-boundary-layer-overlying midlevel lapse rates of 7.5-8.5
C/km attendant to a well-established EML plume, large buoyancy is in
place with SBCAPE of 3000-4000 J/kg. This will support intense
updrafts. Furthermore, with the region being on the eastern
periphery of a belt of enhanced northerlies in the midlevels,
effective shear of 25-35 kt may facilitate a few organized/sustained
convective structures capable of severe hail/wind into the evening
hours. However, without stronger low-level/deep ascent, the coverage
of severe thunderstorms is presently forecast to be too limited for
Watch issuance.

..Cohen/Weiss.. 06/17/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Sab Jun 17, 2017 8:24 pm

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 345
NWS Storm Prediction Center Norman OK
540 PM CDT Sat Jun 17 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Southern and eastern Iowa
Northern and central Illinois
Northeast Missouri
Lake Michigan

* Effective this Saturday afternoon and Sunday morning from 540
PM until 100 AM CDT.

* Primary threats include...
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
A tornado or two possible

SUMMARY...Storms will continue to intensify generally near a front
where the preceding air mass is most and very unstable. With the aid
of an approaching mid/upper-level system and jet streak, relatively
strong deep-layer winds will help organize storms into
east/southeastward-moving bands through the evening. Damaging winds
and severe hail are the primary concerns.

The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 65 miles west northwest
of Quincy IL to 45 miles east of Marseilles IL. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU5).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
28035.

...Guyer

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 346
NWS Storm Prediction Center Norman OK
610 PM CDT Sat Jun 17 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Southern and eastern Kansas
Western and northern Missouri

* Effective this Saturday night and Sunday morning from 610 PM
until 200 AM CDT.

* Primary threats include...
Scattered large hail likely with isolated very large hail events
to 3 inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
A tornado or two possible

SUMMARY...Storms will continue to develop initially along a boundary
that extends from southwest Kansas northeastward into northeast
Kansas and northern Missouri. Very steep lapse rates, strong
buoyancy, and ample deep-layer shear will support the possibility of
supercells capable of very large hail and possibly a tornado. The
potential for damaging winds may increase as storms tend to cluster
this evening and move east-southeastward across the region.

The severe thunderstorm watch area is approximately along and 65
statute miles north and south of a line from 50 miles south of
Kirksville MO to 30 miles southwest of Garden City KS. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU6).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 345...

AVIATION...A few severe thunderstorms with hail surface and aloft to
3 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 650. Mean storm motion vector
28025.

...Guyer

-------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1071
NWS Storm Prediction Center Norman OK
0244 PM CDT Sat Jun 17 2017

Areas affected...northeast Missouri...southeast Iowa...northern
Illinois...far southeast Wisconsin...and far northwest Indiana

Concerning...Severe potential...Watch possible

Valid 171944Z - 172145Z

Probability of Watch Issuance...60 percent

SUMMARY...Deepening cumulus/showers developing at this time across
eastern Iowa and northern Illinois are expected to continue evolving
into isolated thunderstorms. Accompanying risk for locally damaging
winds and hail may require watch issuance.

DISCUSSION...Latest visible satellite loop shows a west-to-east band
of towering cumulus/small Cb developing from just north of MLI to
near ORD, and other deepening in the cu field across far northern
Missouri. This increase in cumulus development is occurring just
ahead of the slowly advancing cold front (extending from Lake
Michigan southwest across southern Wisconsin/eastern Iowa into
northwest Missouri), where gradual airmass destabilization
continues.

Early afternoon RAOBs from DVN -- and particularly from ILX -- show
a warm troposphere/very weak lapse rates in the 850 to 500 mb layer,
which will limit CAPE development over the next few hours despite a
moist boundary layer and continued heating through broken cloud
cover. Still, expect continued/gradual increase in the cu field to
result in isolated thunderstorm development over the next 1-2 hours.

With ample shear indicated by area VWPs and the aforementioned 18z
DVN RAOB, owing to mid-level westerly flow currently in the 30 to 40
kt range, a few of the developing cells may organize, and become
capable of producing hail and locally gusty/damaging winds. While
this development may require WW issuance, greater severe risk is
expected to evolve later this afternoon/early this evening, as a
mid-level short-wave trough/jet streak approaches from the west and
eventually overspreads the area -- yielding an increase in
large-scale ascent and available shear.

..Goss/Weiss.. 06/17/2017

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Mesoscale Discussion 1072
NWS Storm Prediction Center Norman OK
0345 PM CDT Sat Jun 17 2017

Areas affected...Portions of central/southern/eastern KS...western
MO

Concerning...Severe potential...Watch likely

Valid 172045Z - 172315Z

Probability of Watch Issuance...80 percent

SUMMARY...While not imminent, Weather Watch issuance will be likely
at some point later this afternoon or early this evening -- for
portions of the region. Significant severe hail and wind will be
possible. The potential for a couple of tornadoes will also exist.

DISCUSSION...Very strong to extreme instability has developed along
and south of a surface boundary analyzed from south-central IA to
near St. Joseph MO to just north of a line from Topeka to Salina.
The boundary trails farther west into western KS. Near and south of
the boundary, widespread strong insolation amid generally
lower/middle 70s dewpoints and an EML characterized by 8-9-C/km
midlevel lapse rates has resulted in MLCAPE of 4000-6500 J/kg.
Deeper vertical mixing across western parts of southern KS is
associated with a somewhat drier low-level profile and lower
buoyancy.

While these factors are yielding large conditional severe potential,
there is substantial uncertainty regarding the timing of robust
convective development. This is the result of strong capping
aloft -- perhaps related to compensating subsidence peripheral to a
long-lived, decayed MCS presently crossing the Red River into far
northeast TX. In fact, the 20Z Topeka KS special sounding indicates
substantial capping, with MLCINH around 180 J/kg, associated with a
shallow inversion around 850 mb beneath the base of the EML.

Visible satellite trends suggest that the southern periphery of
ACCAS fields are becoming slightly agitated across far northeast KS.
This could be in response to a combination of slight midlevel
cooling grazing the sloped frontal surface peripheral to a midlevel
speed maximum, and/or diurnally enhanced boundary-layer
circulations -- augmented by frontal baroclinicity -- aided by
diabatic surface-layer heating. Convection could develop in these
areas of mesoscale ascent relatively soon despite the antecedent
capping. Needless to say, observational data trends and CAM guidance
are suggesting somewhat variable signals regarding timing/locations
of convective initiation, and confidence in the timing and exact
location of intense convective development are somewhat muted.

Present indications are that supercell development could occur
across parts of central and northeast KS and into northwest and
west-central MO after 2130Z through around 0100Z -- but increasingly
more likely after 2230-2330Z. This will be aided by continued
surface heating and follow initial updraft pulsations along the zone
of convergence attendant to the boundary -- and perhaps aided by the
glancing influence of peripheral midlevel ascent. Additional
development will be likely in the drier air westward along the front
in KS.

The presence of 40-50 kt of effective shear oriented obliquely to
the initiating boundary will initially support discrete and
semi-discrete supercell structures. Very large hail -- potentially
baseball-size hail -- may accompany initial updrafts. Despite
relatively weak low-level shear -- associated with slight diurnal
veering of surface winds south of the boundary amid weak low-level
flow -- intense stretching of pre-existing vertical vorticity will
likely occur with maturing incipient updrafts interacting with the
boundary. As such, some tornado risk could exist during early stages
of convective development. The area of greatest potential for
intense supercells capable of some tornado risk and significant
severe hail will extend within a narrow corridor from around and
south of the Salina and Fort Riley areas toward Topeka and Kansas
City.

However, there should be a tendency for convection to produce
intense outflows -- given DCAPE of 1400-1800 J/kg amid the
well-mixed boundary layer -- while increasing in coverage through
the late afternoon and evening. This will likely curtail the
spatiotemporal window of opportunity for tornado potential, while
the risk for damaging straight-line winds increases. Amalgamating
cold pools will have a tendency of supporting localized clusters of
upscale convective growth as storms spread southeastward and
east-southeastward into the evening hours. Severe winds --
potentially destructive with gusts upwards of 80 mph -- will become
increasingly likely as convection evolves into the evening hours.

..Cohen/Weiss.. 06/17/2017

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Mesoscale Discussion 1073
NWS Storm Prediction Center Norman OK
0354 PM CDT Sat Jun 17 2017

Areas affected...Portions of southeastern Lower MI

Concerning...Severe potential...Watch unlikely

Valid 172054Z - 172300Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated severe potential may accompany storms moving
across parts of southeastern Lower MI through late afternoon.
Present indications are that Watch issuance is unlikely.

DISCUSSION...A small area of convection has intensified in
association with a residual MCV moving across Lower MI. This
activity will continue spreading eastward from parts of central
Lower MI into southeastern/east-central Lower MI during the next few
hours. MLCAPE around 1000-1500 J/kg combined with 25-35 kt of
effective shear may be sufficient for a few semi-organized
convective structures to be maintained with locally damaging wind
gusts possible. Given the limited overlap of MCV-related ascent with
stronger buoyancy, and poor midlevel lapse rates, greater severe
potential is not anticipated.

..Cohen/Weiss.. 06/17/2017
Dome, dome, dome..The life is a dome

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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Dom Jun 18, 2017 5:13 pm

Finalmente, el sistema, empieza a moverse hacia el este y empieza a afectar al noreste y sur de los Estados Unidos. Riesgo marginal a leve. Viento, el riesgo principal.
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Discusión.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Sun Jun 18 2017

Valid 181630Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
TEXAS AND EASTERN OKLAHOMA ACROSS THE TENNESSEE VALLEY INTO THE
LOWER GREAT LAKES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK FROM THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY
INTO THE NORTHEAST STATES...

...SUMMARY...
Scattered thunderstorms with damaging wind gusts and some hail will
be possible through evening between the Red River Valley region of
southern Oklahoma/north Texas and the Northeast.

...Extreme Eastern Oklahoma/northeast Texas into the Tennessee
Valley...
A compact QLCS with bowing structures is moving eastward across
central Arkansas within a very moist air mass with surface dew
points in the middle 70s. Diabatic heating in advance of the system
has warmed temperatures into the low/middle 80s over central/eastern
Arkansas into the mid-South, and with the 12Z LZK sounding
exhibiting a steep lapse rate of 8C/km in the 750-550 mb layer, a
very unstable environment is present with MLCAPE of 2000-3000 J/kg.
VAD wind profiles at INX/Tulsa and SRX/Fort Smith are indicating
40-50 kt west-northwest rear inflow in the trailing stratiform
region suggesting potential for the system to maintain forward
propagation this afternoon, reaching parts of western Tennessee and
northern Mississippi. The primary threat is expected to be damaging
wind gusts although isolated hail is also possible. The activity is
expected to weaken by this evening as it moves into the Tennessee
Valley.

Other storms are increasing over northern parts of western and
middle Tennessee along the leading edge of a small MCS and
immediately ahead of it within a weakly capped but moderately
unstable air mass (MLCAPE of 2000-2500 J/kg). These storms are
located within a weaker flow/vertical shear environment which will
favor a mix of multicell and pulse storm structures, with potential
for stronger storms to produce primarily damaging wind gusts.

...Ohio Valley into the Lower Great Lakes...
12Z soundings across this region showed relatively warm 500 mb
temperatures and modest lapse rates which will limit the magnitude
of buoyancy this afternoon. However, stronger diabatic heating is
occurring from southern Ohio into western parts of Pennsylvania and
New York in advance of a broad pre-frontal cloud band. Within this
region, temperatures are warming into the low/middle 80s with dew
points in the mid/upper 60s, resulting in MLCAPE 1500-2000 J/kg.
Model guidance indicates storms will develop and intensify from
central/northeast Ohio into western New York during the early
afternoon with several clusters and line segments spreading
northeast into the evening hours. As the upper trough moves
eastward across the Great Lakes region, southwest winds aloft in the
low-middle levels will strengthen and create sufficient vertical
shear to promote organized convective structures including isolated
supercells. Damaging wind gusts will be the primary threat with
stronger storms.

..Weiss/Cohen.. 06/18/2017

Próxima actualización: 20:00z.
------------------------------------------------------------------------
Watchs vigentes.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 352
NWS Storm Prediction Center Norman OK
945 AM CDT Sun Jun 18 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Arkansas

* Effective this Sunday morning and afternoon from 945 AM until
400 PM CDT.

* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...A band of strong/severe storms is expected to spread
eastward across Arkansas and intensify into the afternoon hours with
potential to produce damaging wind gusts and occasional hail.

The severe thunderstorm watch area is approximately along and 100
statute miles east and west of a line from 20 miles north northeast
of Batesville AR to 45 miles south southeast of Hot Springs AR. For
a complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU2).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 351...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
28035.

...Weiss

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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 353
NWS Storm Prediction Center Norman OK
135 PM EDT Sun Jun 18 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Western and Central New York
Eastern Ohio
Western Pennsylvania
Northern West Virginia Panhandle
Lake Erie
Lake Ontario

* Effective this Sunday afternoon and evening from 135 PM until
900 PM EDT.

* Primary threats include...
Widespread damaging wind gusts to 70 mph likely
Scattered large hail events to 1.5 inches in diameter possible
A tornado or two possible

SUMMARY...Storms are developing from central Ohio into western new
York in advance of a cold front moving toward the region. Storms
are likely to intensify this afternoon as they move northeastward
with potential to produce damaging wind gusts and occasional hail.

The severe thunderstorm watch area is approximately along and 65
statute miles east and west of a line from 55 miles northeast of
Rochester NY to 20 miles east of Zanesville OH. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 352...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
23030.

...Weiss

---------------------------------------------------------------------------------------------
Últimas discusiones a mesoesacala.
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Mesoscale Discussion 1074
NWS Storm Prediction Center Norman OK
0817 PM CDT Sat Jun 17 2017

Areas affected...Northern and central Illinois...northeastern
Missouri...and far southeastern Iowa

Concerning...Severe Thunderstorm Watch 345...

Valid 180117Z - 180215Z

The severe weather threat for Severe Thunderstorm Watch 345
continues.

SUMMARY...The severe threat continues across WW 345.

DISCUSSION...Scattered to numerous thunderstorms have evolved this
afternoon along/just ahead of a surface boundary along northwestern
portions of WW 345. A few supercell structures have evolved along
with broken linear segments. The severe threat should continue with
this activity as it migrates/propagates southeastward over the next
few hours - greatest in western and central portions of the watch
where instability is the strongest. A severe threat will exist into
northeastern Illinois, although a couple of factors are in play that
may affect the severe threat over the next couple of hours: 1)
somewhat weaker instability with northeastward extent, which may
mitigate the severe threat (as confirmed by recent radar/lightning
presentation of the storms) and 2) a gradual increase in low-level
wind fields over the next couple of hours, and 3) remnant low-level
outflow boundaries, which may result in a brief, localized uptick of
severe activity especially if updrafts can interact with these
boundaries.

With time, activity will continue to migrate southeastward into
central Illinois with a continued hail and wind threat - especially
as low-level flow increases and ascent from an amplifying mid-level
trough over Minnesota approaches. Downstream areas (eastern
Illinois and western Indiana) may experience an increasing severe
threat in the next 1-3 hours in response to current activity near
Peoria. Additionally, significant hail may occur in western
Illinois and northeastern Missouri, especially with storms that can
exhibit stronger updraft rotation.

..Cook.. 06/18/2017

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Mesoscale Discussion 1075
NWS Storm Prediction Center Norman OK
0823 PM CDT Sat Jun 17 2017

Areas affected...Southern into eastern Kansas into western Missouri

Concerning...Severe Thunderstorm Watch 346...

Valid 180123Z - 180330Z

The severe weather threat for Severe Thunderstorm Watch 346
continues.

SUMMARY...Severe hail and wind remain possible across the entire
watch area. Storms are expected to eventually affect far northern
Oklahoma late this evening, and another watch could be required at
that time.

DISCUSSION...Storms continue to fill in along the surface trough
from near Dodge City northeastward into Missouri. A very unstable
air mass remains in place with 4000-5000 MLCAPE observed on the 00Z
DDC and TOP soundings, respectively. Good mid to high level flow
exists, especially over northeastern portions of the area with the
upper jet sinking southward. Although low-level flow remains weak, a
few cells have show midlevel rotation at times, supporting longevity
and hail size. With time, the main cold front is expected to
interact with and undercut the existing corridor of storms, with a
more linear mode expected. Then, a southward drift, which could
bring locally damaging winds into northern Oklahoma.

..Jewell.. 06/18/2017

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Mesoscale Discussion 1076
NWS Storm Prediction Center Norman OK
0934 PM CDT Sat Jun 17 2017

Areas affected...Southeast Kansas...southwest Missouri...northeast
Oklahoma

Concerning...Severe Thunderstorm Watch 346...

Valid 180234Z - 180430Z

The severe weather threat for Severe Thunderstorm Watch 346
continues.

SUMMARY...A threat of severe wind and hail persists across WW 346,
and may extend a bit farther southeast into northeastern Oklahoma
into southwestern Missouri this evening. A new/small watch may be
needed.

DISCUSSION...Scattered severe storms, with a mixture of cells and
lines, persist from southern KS into northern MO. Cells over
southwestern KS have shown very large hail cores at times, as well
as strong winds, and remain relatively discrete. However, a merging
could occur as the cold front continues to undercut. Over eastern
Kansas, cells have merged with a cluster of severe storms just
northeast of Wichita propagating rapidly southward. Damaging winds
and hail are likely with this activity, which will approach the
KS/OK state line by around 0430Z. Farther east, storms continue just
east of the Kansas city area, with indications of damaging winds.

Storms will continue to shift southeastward this evening, and the
air mass remains unstable. However, capping will become a concern,
with 00Z SGF and OUN soundings showing substantial CIN. The greatest
threat of severe wind and hail will be immediately south of WW 346,
but it is unclear how far south these storms will remain
strong/severe.

..Jewell/Guyer.. 06/18/2017

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Mesoscale Discussion 1077
NWS Storm Prediction Center Norman OK
0950 PM CDT Sat Jun 17 2017

Areas affected...Central Missouri...central and southern
Illinois...and western Indiana

Concerning...Severe potential...Watch possible

Valid 180250Z - 180345Z

Probability of Watch Issuance...40 percent

SUMMARY...The discussion area is being monitored for a possible
severe thunderstorm watch issuance over the next couple of hours.

DISCUSSION...Scattered thunderstorms, including a couple of
extensive linear segments from east-central Illinois
west-southwestward to near Kansas City, are moving southeastward and
approaching the discussion area at this time. Moderate (2000-3000
J/kg MUCAPE) instability and 40-50 knots of deep shear will support
a continued threat of damaging winds and hail (especially along
bowing linear structures), although some concern exists downstream
about increasing convective inhibition, which lends uncertainty
about the southeastward extent of the severe threat. Local
extensions of WW 345 may be needed to address the severe threat in
the short term, and a new severe thunderstorm watch will possibly be
needed in the discussion area.

..Cook/Guyer.. 06/18/2017

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Mesoscale Discussion 1078
NWS Storm Prediction Center Norman OK
1155 PM CDT Sat Jun 17 2017

Areas affected...Southeast Kansas...northeast Oklahoma...southwest
Missouri

Concerning...Severe Thunderstorm Watch 347...348...

Valid 180455Z - 180630Z

The severe weather threat for Severe Thunderstorm Watch 347, 348
continues.

SUMMARY...Localized areas of damaging winds and hail may persist for
a couple more hours as storms move out of Kansas.

DISCUSSION...A broken line of cells and small bows continues
southward near the KS border, with winds in excess of 50 kts
measured at multiple sites. Cells have begun to shrivel over far
western areas, with the main threat area now southeast KS into
northeast OK and far southwest MO. Due to capping, storms are
expected to weaken as they near the southern edge of the watch. A
storm or two may remain strong a bit farther south, but another
watch is not expected.

..Jewell.. 06/18/2017

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Mesoscale Discussion 1079
NWS Storm Prediction Center Norman OK
0140 AM CDT Sun Jun 18 2017

Areas affected...East-central and southeast MO/south-central IL

Concerning...Severe Thunderstorm Watch 349...

Valid 180640Z - 180915Z

The severe weather threat for Severe Thunderstorm Watch 349
continues.

SUMMARY...The greatest severe-weather threat in the short term (next
2-3 hours or through 09Z) is expected to be across east-central and
part of southeast MO through south-central IL. Locally
strong/damaging winds will be the primary threat, though hail cannot
be ruled out with the stronger/sustained storms.

DISCUSSION...Trends in VWP data at LSX indicated strong 50-kt
westerly winds between 2.5-4.5 km agl likely supporting a recent
eastward surge in a band of storms across east-central MO (44-kt
wing gust at KSUS at 0603Z). This band of storms is moving to the
east-southeast at around 40 kt into a residual corridor of moderate
instability located across southeast MO to southern IL. Although
most surface wind gusts during the last hour have been sub-severe,
this recent observation of a stronger rear-inflow jet and
sub-synoptic surface low nearby in west-central IL may support
locally strong/damaging winds occurring across south-central IL
through 09Z. This would support local areal expansion of WW 349,
and the rest of southern IL will be monitored for any additional
need for a downstream severe-thunderstorm watch, if the east-central
storms begin to accelerate. Further support for an increase in
storm intensity overnight in this region is attendant to height
falls within the southern extent of an upper MS/lower MO Valleys
upper trough.

..Peters.. 06/18/2017

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Mesoscale Discussion 1080
NWS Storm Prediction Center Norman OK
0344 AM CDT Sun Jun 18 2017

Areas affected...Parts of central and eastern OK

Concerning...Severe Thunderstorm Watch 347...348...

Valid 180844Z - 181045Z

The severe weather threat for Severe Thunderstorm Watch 347, 348
continues.

SUMMARY...Large hail and locally strong/damaging wind gusts remain a
severe-weather threat across north-central into parts of central and
eastern OK overnight to early this morning. Given the recent
increase in storms across north-central OK and potential for
additional storms, a new WW is being considered for parts of central
and eastern OK.

DISCUSSION...Trends in mosaic radar imagery showed an increase in
storm intensity and potential severity (increase in MRMS MESH) with
storms across north-central OK since 06Z. Meanwhile, radar imagery
also indicated southward-moving gravity waves across OK, with an
associated wind shift extending generally east-west across the
middle part of the state (or along and south of I-40). This
atmospheric phenomenon indicates the presence of a strong cap as
observed by the 00Z OUN sounding. A 30-45-kt southwesterly
low-level jet extending into central OK per VWP data at FDR/TLX is
resulting in strong low-level warm advection across central and
southern OK, and supporting the continued development of new
thunderstorms from Logan to Alfalfa Counties. Cooling cloud tops
across north-central OK per IR satellite imagery are suggesting a
strengthening trend with the north-central OK storms.

00Z NAM suggests the low-level jet will veer to west-southwest by
12Z. The current motion of the Logan/Payne Counties storm is toward
the southeast. However, the veering low-level jet would suggest a
more southward trend in activity as it moves into central OK,
possibly reaching PVJ and ADH in addition to MLC by 11-12Z. The
presence of steep midlevel lapse rates per 00Z soundings,
most-unstable CAPE of 3000-3500 J/kg per objective analyses, and
effective bulk shear of 35-50 kt should result in additional strong
to severe storms developing/spreading to the south/southeast across
central and parts of eastern OK through the early morning. The
presence of strong surface-based inhibition with south and southwest
extent across OK could prove to be a limiting factor for the western
delineation of strong/severe storms, with activity remaining mainly
east of I-35 in southern OK.

..Peters.. 06/18/2017

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Mesoscale Discussion 1081
NWS Storm Prediction Center Norman OK
0448 AM CDT Sun Jun 18 2017

Areas affected...Far southern IL...parts of southern IN...and
western and northwestern KY

Concerning...Severe Thunderstorm Watch 350...

Valid 180948Z - 181145Z

The severe weather threat for Severe Thunderstorm Watch 350
continues.

SUMMARY...Greatest severe-weather threat (primarily with damaging
winds) will continue to spread across southwest into south-central
IN and parts of western and northwestern KY early this morning. The
overall severe-weather threat should continue to diminish across far
southern IL.

DISCUSSION...Trends in lightning data and fast storm movement
(east-southeast at 40-45 kt) with storms that have moved into
southwest IN suggest a continued severe-weather threat across this
portion of WW 350 through 10-12Z. If forward motion is maintained
through 1030-11Z, portions of northwest KY (Breckinridge and Meade
Counties) to Harrison County IN may need to be added to this watch.
The ongoing storms in southwest IN are moving through the axis of
strongest instability, while most-unstable CAPE weakens with
eastward extent into central KY. This observation and potential for
further boundary layer stabilization early this morning could
eventually limit the severe-weather threat east of WW 350.

Meanwhile, the decrease in storm movement and diminishing lightning
trends across southern IL suggests the overall severe-weather threat
in this portion of WW 350 should continue to wane.

..Peters.. 06/18/2017

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Mesoscale Discussion 1082
NWS Storm Prediction Center Norman OK
0718 AM CDT Sun Jun 18 2017

Areas affected...Central and eastern OK

Concerning...Severe Thunderstorm Watch 351...

Valid 181218Z - 181415Z

The severe weather threat for Severe Thunderstorm Watch 351
continues.

SUMMARY...Greatest severe-weather threat (hail and damaging winds)
is expected to be mainly across the northern half of WW 351 through
14Z (9 AM). Local WFO areal expansion of WW 351 is possible across
parts of northeast and east-central OK.

DISCUSSION...At 1205Z, radar imagery indicated a band of storms
extending from Craig and Mayes Counties to Okfuskee County moving to
the east-southeast at 30-35 kt. Steep midlevel lapse rates (7.5-8.5
C/km per objective analyses extending from far western AR through
central/southern OK) and effective bulk shear of 35-50 kt suggest
any sustained storms will continue to have a threat for large hail.
Otherwise, locally strong wind gusts will remain a threat, with
uncertainty for damaging winds, given the lack of severe wind gusts
in the last 2-3 hours. Current radar trends and latest HRRR suggest
storms will progress through northeast and east-central OK toward an
area of undisturbed high theta-e air residing in western AR per
objective analyses. Meanwhile, the presence of stronger
surface-based inhibition with southward and southwestward extent in
OK should continue to inhibit storm development in those directions.

..Peters.. 06/18/2017

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Mesoscale Discussion 1083
NWS Storm Prediction Center Norman OK
0805 AM CDT Sun Jun 18 2017

Areas affected...Northern and central AR

Concerning...Severe potential...Watch possible

Valid 181305Z - 181500Z

Probability of Watch Issuance...40 percent

SUMMARY...A new WW may be needed across parts of northern and
central AR this morning into the afternoon, as storms move into AR
from eastern OK by mid morning.

DISCUSSION...A cluster of storms located in east-central and
northeast OK to far northwest AR should continue to advance to the
east-southeast across the northern half of AR through this morning,
as the pre-convective air mass destabilizes. Trends in morning
visible satellite imagery indicated surface heating should occur
across much of west-central, central to eastern AR today aiding in
further destabilization and reduction of present inhibition per 12Z
LZK sounding. A moist environment (mean-mixing ratio at or above 17
g/kg) would support additional convection within the destabilizing
downstream air mass. The presence of weak lower tropospheric flow
per 12Z OUN/LZK soundings is a limiting factor for greater storm
organization, with recent surface observations across eastern OK
having sub-severe wind gusts.

..Peters/Edwards.. 06/18/2017

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Mesoscale Discussion 1084
NWS Storm Prediction Center Norman OK
1131 AM CDT Sun Jun 18 2017

Areas affected...portions of western and central New York...northern
and western Pennsylvania...central and eastern Ohio...and the
northern West Virginia Panhandle

Concerning...Severe potential...Watch possible

Valid 181631Z - 181830Z

Probability of Watch Issuance...60 percent

SUMMARY...A gradually increasing cu field will likely lead to
scattered thunderstorm development over the next 1-2 hours. With an
associated risk for locally damaging winds and marginal hail likely
to accompany stronger storms, WW issuance may be required.

DISCUSSION...Latest visible satellite loop shows an increasing
cumulus coverage/depth from southwest Ohio northeast to northwest
Pennsylvania and western New York, in the vicinity of Lake Erie.
This appears to be loosely tied to a pre-frontal confluence axis
lying across central Ohio, and hints of a lake-breeze boundary over
western New York.

Diurnal heating through broken cloud cover in conjunction with
boundary-layer dewpoints mainly in the upper 60s is supporting
mixed-layer cape now in excess of 1000 J/kg across the area, with
additional heating/destabilization expected to fuel eventual
development of scattered thunderstorms -- aided increasing
large-scale ascent spreading across the region ahead of the upper
Great Lakes short-wave trough.

Morning RAOBs and the latest VWP data from the region indicate
moderate/roughly unidirectional southwesterly flow with height,
which will support some updraft organization and likely eventual
upscale growth into lines/bands of storms. With resulting potential
for locally damaging winds arising from the organizing convection,
along with some risk for hail, indications are that a WW will likely
be required across this area within the next 1-2 hours.

..Goss/Weiss.. 06/18/2017

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Mesoscale Discussion 1085
NWS Storm Prediction Center Norman OK
1236 PM CDT Sun Jun 18 2017

Areas affected...central and eastern Arkansas

Concerning...Severe Thunderstorm Watch 352...

Valid 181736Z - 181930Z

The severe weather threat for Severe Thunderstorm Watch 352
continues.

SUMMARY...A few vigorous storms -- and local severe risk -- continue
moving east across parts of WW 352.

DISCUSSION...Latest radar loop shows a rather loosely organized line
of strong storms crossing central Arkansas at this time, with some
development ahead of the main convective band currently ongoing.
The main band of storms -- moving east at around 35 kt -- has
generally weakened over the past hour, while a few locally vigorous
storms have developed just ahead of northern portions of the band.
Overall, with storms advancing into an axis of moderate (2500 to
3000 J/kg) mixed-layer CAPE near the Mississippi Valley, expect
local severe risk to continue. Eventually, storms are forecast to
spread/develop eastward across the Mississippi River, where a new WW
may be considered a bit later this afternoon.

..Goss.. 06/18/2017

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Mesoscale Discussion 1086
NWS Storm Prediction Center Norman OK
0148 PM CDT Sun Jun 18 2017

Areas affected...parts of eastern Arkansas and into western
Tennessee and northern Mississippi

Concerning...Severe Thunderstorm Watch 352...

Valid 181848Z - 182045Z

The severe weather threat for Severe Thunderstorm Watch 352
continues.

SUMMARY...Local severe risk continues across parts of eastern
Arkansas; as storms gradually spread across the river into parts of
western Tennessee and northern Mississippi, local severe risk will
expand into these areas.

DISCUSSION...Latest radar loop shows a band of storms continuing to
move east across eastern Arkansas, through an axis of 3000 J/kg
mixed-layer CAPE per objective analysis. While flow aloft remains
relatively weak downstream, degree of instability and the organizing
presence of outflow at the leading edge of the convective cold pool
suggests at least some risk for locally damaging winds east of the
river. As such, ww 352 will be locally expanded eastward to cover
potential wind risk.

..Goss.. 06/18/2017

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Mesoscale Discussion 1087
NWS Storm Prediction Center Norman OK
0231 PM CDT Sun Jun 18 2017

Areas affected...Portions of PA...central/eastern NY...western VT

Concerning...Severe potential...Watch possible

Valid 181931Z - 182200Z

Probability of Watch Issuance...60 percent

SUMMARY...There could be an increase in the severe-thunderstorm
potential within the next few hours, with such risk continuing into
the evening. The issuance of one or more Severe Thunderstorm Watches
will be possible at some point later this afternoon.

DISCUSSION...Beneath the eastern rim of broadly cyclonic midlevel
flow, a moist and diurnally destabilizing boundary layer will
support an increase in thunderstorm potential during the next few
hours. Organizing quasi-linear convective bands across western PA/NY
may spread east of Watch 353, with additional storm development
possible in the uncapped and moderately unstable environment farther
east. With surface dewpoints holding in the middle 60s to lower 70s
amid widespread insolation, MLCAPE around 1000-2000 J/kg is in place
across the region, which will offer support for vigorous updrafts.
However, poor midlevel lapse rates will tend to mute upward
convective-scale accelerations to some extent, resulting in a slow
uptick in intensity for convection not already established.

Given 30-40 kt of midlevel southwesterly flow per area VAD wind
profiles, along with some low-level veering of the flow with height
above ground particularly in NY, sufficient vertical shear will
exist for a mix of organized convective lines, multicells, and
perhaps a few transient supercell structures. Damaging winds will be
the primary concern with this activity, though marginally severe
hail could accompany discrete, rotating updrafts.

The timing of a more robust increase in severe potential is somewhat
uncertain owing to the overall dearth of deep ascent, limited
low-level convergence, and poor lapse rates aloft. These factors
could also limit severe coverage. However, a general increase in
severe risk will exist through the next few hours, with the severe
risk continuing into the evening as convection spreads
eastward/northeastward across the region.

..Cohen/Weiss.. 06/18/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Dom Jun 18, 2017 5:50 pm

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Mesoscale Discussion 1088
NWS Storm Prediction Center Norman OK
0330 PM CDT Sun Jun 18 2017

Areas affected...Portions of western/central NY...western
PA...eastern OH...northern WV Panhandle

Concerning...Severe Thunderstorm Watch 353...

Valid 182030Z - 182200Z

The severe weather threat for Severe Thunderstorm Watch 353
continues.

SUMMARY...The severe risk in Severe Thunderstorm Watch 353
continues.

DISCUSSION...Convection has organized into quasi-linear segments
from western NY to western PA trailing southwestward into the
northern WV Panhandle and east-central OH. This activity will
continue spreading eastward/northeastward through late afternoon and
remain capable of producing damaging wind gusts, while ingesting
generally moist inflow associated with 1000-1500 J/kg of MLCAPE.
However, a northward flux of a somewhat drier boundary layer from
northern WV may tend to curtail subsequent convective development on
the south end of the broken convective bands in southern PA.

West of the more organized convection, a narrow corridor of
destabilization/air-mass recovery lies ahead of convection crossing
north-central OH. This upshear activity may eventually pose a local
strong-wind risk across other parts of eastern OH. Relatively
stronger deep shear -- e.g., effective shear of 30-35 kt -- exists
in these areas.

The aforementioned severe risk -- preceded by new cell development
from central PA to north-central NY perhaps eventually yielding
severe potential -- may spread east/northeast of Watch 353 soon.
This could warrant the issuance of one or more additional Severe
Thunderstorm Watches, as addressed in Mesoscale Discussion 1087.

..Cohen.. 06/18/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Lun Jun 19, 2017 9:39 pm

Tiempo severo en la costa este y noreste de los Estados Unidos. Viento, el riesgo principal.
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Discusión.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0251 PM CDT Mon Jun 19 2017

Valid 192000Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER
CENTRAL/EASTERN VIRGINIA...THE DISTRICT OF
COLUMBIA...NORTHERN/EASTERN MARYLAND...DELAWARE...EXTREME EASTERN
PENNSYLVANIA...NEW JERSEY...SOUTHEAST NEW YORK...CONNECTICUT AND
MASSACHUSETTS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED RISK FROM NORTH CAROLINA INTO NEW ENGLAND...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
MISSISSIPPI VALLEY INTO PARTS OF THE SOUTHEAST STATES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
TEXAS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
NORTH DAKOTA AND NORTHWEST MINNESOTA...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MIDDLE
MISSISSIPPI VALLEY TO THE LOWER GREAT LAKES...

...SUMMARY...
Strong to severe thunderstorms are forecast over parts of the
Northeast into the Mid-Atlantic states through this evening.
Damaging wind gusts will be the primary severe hazard but a tornado
or two and some hail may also be possible. Isolated strong to
severe thunderstorms are possible farther southwestward across parts
of the Southeastern states, and over south-central and southwest
parts of Texas late this afternoon and evening.

Several lines of strong/severe storms are progressing across the
Mid-Atlantic states and New England, with a continued threat for
primarily damaging wind gusts into the evening hours. The western
edge of the severe outlook area has been adjusted to reflect the
location of the current thunderstorm activity, with the severe
threat gradually ending from the west.

Otherwise, the marginal risk area over the Texas/Louisiana region
has been adjusted to focus primarily over south-central and
southwest Texas. This area is along/west of the MCV moving
southward into south-central Texas where a convergence boundary
extends west-southwest to the north of Marfa. See MD 1097 for
additional details over this area.

..Weiss.. 06/19/2017

.PREV DISCUSSION... /ISSUED 1127 AM CDT Mon Jun 19 2017/

...Portions of the Eastern States...
Little overall change has been made to the ongoing forecast.
Convection will continue deepening along the eastern fringes of a
multi-layered cloud band from northern NY to the southern
Appalachians through the afternoon hours. Convection will most
notably develop in the short term from the Mid-Atlantic to New
England in closer proximity to at least 30-meter/12-hour 500-mb
height falls, with convection subsequently developing southward as
diurnal heating continues. Numerous bands of convection will
elongate north-northeastward while shifting east, ahead of a deeper
baroclinic zone crossing the Great Lakes region. As a diffuse warm
front advances north across New England, a corridor of 1000-2500
J/kg of MLCAPE will continue to extend north with time -- primarily
driven by rich boundary-layer moisture (e.g., 15.5 g/kg mean mixing
ratio per Brookhaven NY 12Z sounding). Given 25-35 kt of flow around
1-km above ground per VAD wind profiles over the meridionally
extensive moist sector/surface dewpoints in the 70s, scattered
damaging wind gusts will be likely -- enhanced in association with
line-embedded meso-vortices/small rear inflow jets. Convection will
spread toward the Atlantic coast through the evening before
weakening as it moves offshore while also encountering a stable
marine layer across northeastern parts of New England.

The greatest concentration of damaging wind is expected across the
Enhanced Risk area. Across the surrounding Slight Risk area, weaker
buoyancy across northern New England, and somewhat warmer midlevel
profiles and a weaker low-level mass response across the NC/SC
Piedmont will limit the severe risk in those areas.

...South of the southern extent of the Slight Risk area from parts
of the Southeast States to Texas...
A moist and uncapped boundary layer will continue to destabilize
where surface heating is the strongest. Low-level ascent along a
weak surface boundary -- augmented by outflow accompanying a
persistent convective cluster in central TX -- will support a
corridor of isolated to scattered thunderstorm potential into the
early evening hours. Weak deep shear should limit convective
organization, while a few strong microbursts potentially support
isolated damaging winds.

...Portions of ND into western MN...
Clusters of convection will increase ahead of a compact midlevel
impulse advancing southeastward from Saskatchewan. Despite a dearth
of tropospheric moisture, long mid/high-level hodographs and
moderate midlevel lapse rates may support a few persistent
convective elements capable of isolated severe hail/wind.

...Portions of eastern IA/southern WI to western OH...
Cold midlevel conditions above a diurnally warming, though
relatively dry, boundary layer will support sufficient instability
for sustained convective clusters to move across the region into
early evening. Sufficient deep shear and high-level flow may support
weakly organized convective structures capable of isolated severe
hail/wind.

Próxima actualización: 01:00z.
------------------------------------------------
Watch vigente.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 356
NWS Storm Prediction Center Norman OK
1250 PM EDT Mon Jun 19 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
District Of Columbia
Maryland
Northern North Carolina
Virginia
Eastern Panhandle of West Virginia
Coastal Waters

* Effective this Monday afternoon and evening from 1250 PM until
800 PM EDT.

* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Scattered large hail events to 1.5 inches in diameter possible

SUMMARY...Thunderstorms are forecast to strengthen over
western/central Virginia and spread across the watch area this
afternoon. Locally damaging wind gusts and hail will be possible in
the stronger cells.

The severe thunderstorm watch area is approximately along and 70
statute miles east and west of a line from 40 miles north northeast
of Baltimore MD to 10 miles east southeast of Danville VA. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU6).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 354...WW 355...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
25030.

...Hart

------------------------------------------
Últimas discusiones.
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Mesoscale Discussion 1089
NWS Storm Prediction Center Norman OK
0322 AM CDT Mon Jun 19 2017

Areas affected...Parts of northern and central TX

Concerning...Severe potential...Watch possible

Valid 190822Z - 191045Z

Probability of Watch Issuance...60 percent

SUMMARY...A continued increase in storm coverage/intensity is
expected southward across the Red River into north-central and
northeast TX through 10-11Z, with isolated hail being the primary
threat. Then, the potential exists for greater storm organization
as a forecast south-southwestward propagating MCS spreads across the
I-30 and I-20 corridors of northeast TX and much of the DFW
Metroplex through 12-15Z. Strong/damaging winds would be the
primary severe risk. If this MCS develops, it should move
south-southwest toward far northern portions of the EWX and eastern
portions of the SJT forecast areas later this morning.

DISCUSSION...Since 06Z, trends in mosaic radar imagery and lightning
data indicated a gradual increase in thunderstorm coverage and
intensity across south-central and southeast OK, with this activity
located along a southward-moving 950-mb or 850-mb thermal gradient.
This storm development confirms the last several runs of the HRRR
for storm coverage and placement through 08Z. Meanwhile, models
suggest and water-vapor imagery indicated an apparent weak midlevel
impulse tracking south-southeast through southern OK toward northern
TX. Forcing for ascent/weak height falls attendant to this impulse
will support additional storm development southward into
north-central-northeast TX through 10-11Z. Surface analysis showed
a cold front extending from eastern and southern AR through northern
TX (bisecting the DFW Metroplex), and then southwestward to south of
SJT.

00Z soundings and objective analyses indicated strong instability
and steeper midlevel lapse rates were present with southward extent
across TX. Since 07Z, MRMS MESH data indicated periodic increases
in hail size (to near 1 inch) as ongoing storms have moved into the
far southeast part of OK, closer to the more favorable thermodynamic
environment. Objective analyses also indicated weaker inhibition
near the front in north-central to northeast TX, suggesting storms
will have a greater likelihood to become surface-based with a
subsequent increase in the wind threat.

The 03Z ESRL HRRR, 00Z high-res 4-km NMM and ARW, and consecutive
runs of the HRRR suggest ongoing storms will organize into a
south-southwestward propagating MCS through northeast and
north-central TX (including the DFW Metroplex) during the 12-15Z
period. Although a modest low-level jet should develop this morning
across north TX (from the south-southwest at 25 kt), northwesterly
flow aloft will result in sufficient effective bulk shear for storm
organization, and an enhanced severe-weather threat.

..Peters/Edwards.. 06/19/2017

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Mesoscale Discussion 1090
NWS Storm Prediction Center Norman OK
0945 AM CDT Mon Jun 19 2017

Areas affected...Parts of the northern Mid Atlantic Coast region
into New England

Concerning...Severe potential...Watch likely

Valid 191445Z - 191715Z

Probability of Watch Issuance...95 percent

SUMMARY...Increasing thunderstorm activity is expected into and
through the 1-4 PM EDT time frame, accompanied by a risk for
potentially damaging wind gusts. At least a couple of severe
weather watches appear likely within the next hour or two.

DISCUSSION...Ahead of lingering pre-frontal convection, insolation
within a seasonably high moisture content boundary layer (surface
dew points near/above 70F) is contributing to moderately large CAPE
and weakening inhibition. This is occurring from the lee of the
Allegheny Mountains through much of the Hudson/Champlain Valleys
into the mountains of northern New England, where lower/mid
tropospheric flow is already cyclonic and modest in strength.
Although large-scale upstream troughing is only very slowly
progressing eastward, weak mid-level height falls associated with
subtle embedded perturbations may aid storm development into the
17-20Z time frame.

The initiation of thunderstorms already appears underway across the
Poconos, Catskills into and northeast of the Berkshires, and a
gradual increase in coverage/intensification seems probable into
early afternoon. Eventually, in the presence of soundings that
appear characterized by high precipitable water and 30-40 kt south
to southwesterly lower/mid tropospheric flow, heavy precipitation
loading and downward momentum transfer may contribute to increasing
potential for downbursts. Consolidating and strengthening cold
pools may also contribute to organizing convection accompanied by
strong, potentially damaging wind gusts.

..Kerr/Hart.. 06/19/2017

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Mesoscale Discussion 1091
NWS Storm Prediction Center Norman OK
1114 AM CDT Mon Jun 19 2017

Areas affected...Much of central and eastern Maryland/Virginia

Concerning...Severe potential...Watch likely

Valid 191614Z - 191815Z

Probability of Watch Issuance...95 percent

SUMMARY...Increasing thunderstorm development appears likely during
the next few hours, and may begin impacting the Baltimore/Washington
D.C. metropolitan areas by 2-4 PM EDT.

DISCUSSION...Thunderstorm development is now underway along and
southeast of the Allegheny Mountains, as far south as the eastern
West Virginia panhandle. This appears to coincide with the
southeastern periphery of the stronger mid-latitude latitude
westerlies, which may gradually edge toward the Baltimore/Washington
D.C. metropolitan areas toward the 18-20Z time frame. As the
increasingly weakly capped moist boundary layer continues to
destabilize with additional insolation, this is expected to result
in increasing and intensifying thunderstorm development. In the
presence of 30-40 kt south to southwesterly mean lower/mid
tropospheric flow, heavy precipitation loading and downward momentum
transfer are expected to slowly lead to increasing potential for
downbursts.

Farther to the east and south, into parts of the Carolina piedmont
and Mid Atlantic coastal plain, where mid-level heights remain
fairly high and flow appears a bit weaker, but at least broadly
cyclonic, a general increase in thunderstorm development and
intensity appears probable through late afternoon.

..Kerr/Hart.. 06/19/2017

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Mesoscale Discussion 1092
NWS Storm Prediction Center Norman OK
1203 PM CDT Mon Jun 19 2017

Areas affected...Portions of NC/SC

Concerning...Severe potential...Watch possible

Valid 191703Z - 191930Z

Probability of Watch Issuance...40 percent

SUMMARY...The area will continue to be monitored for a slow increase
in severe-thunderstorm potential through the afternoon. It is
unclear whether convective organization and severe coverage will be
sufficient for Watch issuance, though the issuance of a Severe
Thunderstorm Watch may be possible at some point this afternoon.

DISCUSSION...Low-level lapse rates are steepening in response to
strong insolation amid a moist boundary layer characterized by
surface dewpoints generally in the lower/middle 70s. Buoyancy is
primarily being driven by the rich moisture, with 1500-2500 J/kg of
MLCAPE in place with minimal capping. However, midlevel lapse rates
are quite modest, which should mute upward convective-scale
accelerations and slow the overall process for convective
development -- especially as stronger deep ascent remains well to
the north of the region.

Nevertheless, low-level ascent associated with the following regimes
will be sufficient for a gradual uptick in the number of intensity
of thunderstorms during the next few hours:
(1) Diurnally enhanced orographic circulations over the southern
Appalachians,
(2) Differential-heating-induced baroclinicity along the eastern
edges of a persistent multi-layered cloud band over far western
parts of the Carolinas,
(3) Deepening boundary-layer circulations over the Piedmont region,
and
(4) Sea-breezes boundaries over the coastal plain.

With time, amalgamating cold pools should foster multicell clusters
spreading eastward and northeastward through the early evening
hours, aided by 25-30 kt of effective shear. While DCAPE upwards of
1000 J/kg will be somewhat marginal for intense downdrafts, the
substantive upward buoyancy may prove sufficient for localized
corridors of greater damaging-wind potential. Regardless, weak deep
ascent, modest midlevel lapse rates, and modest low-level flow/deep
shear all detract confidence in a more substantial severe risk
evolving, though convective/environmental trends will continue to be
monitored.

..Cohen/Hart.. 06/19/2017

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Mesoscale Discussion 1093
NWS Storm Prediction Center Norman OK
1244 PM CDT Mon Jun 19 2017

Areas affected...Portions of eastern IA...southern WI...northern
IL...northern/central IN...southwest Lower MI...western OH

Concerning...Severe potential...Watch unlikely

Valid 191744Z - 192015Z

Probability of Watch Issuance...5 percent

SUMMARY...Convection crossing parts of the southwest Great Lakes
region may produce isolated and marginally severe hail/wind this
afternoon. However, Watch issuance will not be necessary.


DISCUSSION...The base of a deep trough and accompanying cold
midlevel temperatures are in place across the region. The 12Z
sounding at Davenport IA sampled a 500-mb temperature around
-17.7C -- highlighting the seasonally anomalously cold air aloft.
With strong diabatic surface heating owing to insolation, low-level
lapse rates are steepening, and a southeastward-moving convective
cluster has developed in south-central WI within the general
left-exit region of a high-level speed maximum. Additional cumulus
fields are deepening from parts of central IA and within an arc from
northern IL to northern Indiana, which may eventually evolve into
lightning-producing, though somewhat shallow convection. As all of
this activity spreads southeastward/eastward across the region
through the afternoon hours, unidirectional wind profiles --
elongated in the mid/high levels -- may support sustained convective
cells/clusters. Steep low-to-mid-level lapse rates and relatively
low freezing-level heights may support isolated severe hail, while
well-mixed boundary layers and related sub-cloud evaporation
encourage some risk for isolated damaging wind gusts. However, the
dearth of tropospheric moisture, and the paucity of buoyancy will
limit the overall severe risk.

..Cohen/Hart.. 06/19/2017[/Spoiler]
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Mesoscale Discussion 1094
NWS Storm Prediction Center Norman OK
0121 PM CDT Mon Jun 19 2017

Areas affected...Parts of northern Virginia...central/eastern
Maryland...northern Delaware...southeastern Pennsylvania...northern
New Jersey and the lower Hudson Valley

Concerning...Severe Thunderstorm Watch 354...356...

Valid 191821Z - 192015Z

The severe weather threat for Severe Thunderstorm Watch 354, 356
continues.

SUMMARY...Thunderstorms accompanied by heavy rain, frequent cloud to
ground lightning and increasing (potentially damaging) strong wind
gusts may impact much of the Northeast urban corridor (DC to New
York) by 3-5 PM EDT.

DISCUSSION...Continuing insolation has warmed surface temperatures
to around 90F through much of the urban corridor from Washington
D.C./Baltimore through Philadelphia and New York City. This is
contributing to sizable CAPE on the order of 2000 J/kg, ahead of
evolving upstream thunderstorm activity which continues to gradually
organize and intensify.

Through 20-21Z, a consolidating and strengthening cold pool
associated with the evolving convective system seems likely to surge
northeastward and eastward into the urban corridor, accompanied by
increasingly widespread (and potentially damaging) surface gusts on
its leading edge. This may be enhanced as convection encounters
stronger southerly ambient low-level wind fields, as suggested by
the latest Rapid Refresh, on the order of 40+ kt.

..Kerr.. 06/19/2017

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Mesoscale Discussion 1095
NWS Storm Prediction Center Norman OK
0142 PM CDT Mon Jun 19 2017

Areas affected...Portions of ND and western MN

Concerning...Severe potential...Watch unlikely

Valid 191842Z - 192115Z

Probability of Watch Issuance...5 percent

SUMMARY...There will exist some isolated severe hail/wind potential
with convection spreading across the area from this afternoon into
the early evening. Watch issuance is unlikely.

DISCUSSION...Convection has exhibited slight intensification within
a band of midlevel ascent from southeast Saskatchewan to southwest
Manitoba, preceding a compact vorticity maximum embedded within
40-50 kt of 500-mb northwesterly flow. Continued diurnal heating of
a relatively dry boundary layer ahead of this disturbance will
continue to contribute to marginal instability, with MLCAPE around
250-500 J/kg though with lacking MLCINH. As such, convection will
spread into and across the discussion area throughout the afternoon
and into the evening, and may increase in intensity during the next
few hours. Moderately strong mid/high-level flow will support ample
convective ventilation and sufficient deep shear for sustained
convective cells. Moderately steep midlevel lapse rates may support
isolated marginally severe hail. Also, as low-level lapse rates
steepen, the potential for well-mixed/dry low-level profiles to
support evaporatively cooled downdrafts will exist. Isolated
marginally severe wind gusts will be possible. While the compact
nature of the upstream disturbance and related preceding
upward-motion response will likely support some severe potential,
the overall dearth of moisture and paucity of buoyancy should render
overall limited/marginal severe potential.

..Cohen/Hart.. 06/19/2017

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Mesoscale Discussion 1096
NWS Storm Prediction Center Norman OK
0158 PM CDT Mon Jun 19 2017

Areas affected...Interior southern New England...New Hampshire and
western/northern Maine

Concerning...Severe Thunderstorm Watch 354...355...

Valid 191858Z - 192100Z

The severe weather threat for Severe Thunderstorm Watch 354, 355
continues.

SUMMARY...Thunderstorms accompanied by locally heavy rain, frequent
lightning and potentially damaging wind gusts will overspread the
region through 4-6 PM EDT.

DISCUSSION...Insolation has warmed surface temperatures through the
lower/middle 80s within a narrow pre-frontal corridor across
interior southern New England through the higher terrain of
western/northern Maine. This appears to be contributing to mixed
layer CAPE on the order of 1000-2000 J/kg, and likely will provide
the focus for the most vigorous thunderstorm development through
20-22Z. This will be accompanied by the risk for potentially
damaging surface gusts, particularly from near/northwest of
Worcester through areas near/west and north of Manchester/Concord
NH, where it appears that ambient southerly 850 mb flow has
increased in excess of 40 kt.

..Kerr.. 06/19/2017

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Mesoscale Discussion 1097
NWS Storm Prediction Center Norman OK
0240 PM CDT Mon Jun 19 2017

Areas affected...Portions of southwest TX

Concerning...Severe potential...Watch unlikely

Valid 191940Z - 192215Z

Probability of Watch Issuance...5 percent

SUMMARY...A very isolated severe risk may accompany thunderstorms
into the early evening hours, though Watch issuance will not be
necessary.

DISCUSSION...An uptick in cumulus fields has been noted in proximity
to a boundary extending east-northeastward from the TX Trans-Pecos
region toward areas north of San Angelo. Strong diabatic
surface-layer heating is supporting erosion of antecedent capping
aloft, with favorably moist low-level profiles yielding
2500-3500 J/kg of MLCAPE near the boundary. Convergence near the
boundary -- perhaps aided by the peripheral influence of a decaying,
though persistent, convective cluster crossing the TX Hill
Country -- could support deeper convective development during the
next few hours, with storms potentially lingering into the early
evening. Furthermore, orographic ascent over the southwest TX
mountains could encourage storm formation. Given the aforementioned
buoyancy, a few intense updrafts capable of producing severe hail
could evolve. Also, with DCAPE increasing to around 1300-1700 J/kg,
some isolated severe-wind risk could occur. However, with the region
being displaced to the west of modestly stronger deep shear,
convective organization should be greatly lacking, and any severe
risk should be very isolated.

..Cohen/Hart.. 06/19/2017

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Mesoscale Discussion 1098
NWS Storm Prediction Center Norman OK
0543 PM CDT Mon Jun 19 2017

Areas affected...Central North Carolina into northern South Carolina

Concerning...Severe potential...Watch possible

Valid 192243Z - 200045Z

Probability of Watch Issuance...40 percent

SUMMARY...Areas of thunderstorms are expected to persist and/or
reform across the Carolinas through evening, and a few could contain
a marginal wind, hail, or even brief/weak tornado threat.

DISCUSSION...Numerous storms currently exist across southern VA,
with area of storms into central NC into northern SC being enhanced
by a northwestward-surging outflow boundary. Satellite imagery shows
pockets of heating, and surface obs maintain a very moist air mass
with dewpoints into the mid 70s. Even behind the aforementioned
boundary, the air mass remains unstable. However, lapse rates aloft
are relatively weak.
Winds aloft are marginally favorable for severe storms, especially
over NC near the base of the upper trough. Area VWPs indicate
veering winds with height in the low levels, suggesting marginal
supercell potential. The primary cold front remains well to the
west, and will not move much. But, given the unstable air mass and
multiple outflow boundaries around, storms could redevelop anywhere.
The most likely severe threat is localized damaging wind gusts, but
a brief/weak tornado can not totally be ruled out with such a
chaotic, yet slightly supportive boundary layer.

..Jewell/Guyer.. 06/19/2017
Dome, dome, dome..The life is a dome


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