Seguimiento general en EEUU

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mar Jun 20, 2017 12:47 am

Última actualización del SPC. Riesgo leve a marginal en la costa sur del este de los Estados Unidos. Viento y granizo, los riesgos principales.
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Discusión.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 PM CDT Mon Jun 19 2017

Valid 200100Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM DELAWARE
SOUTHWEST TO CENTRAL NORTH CAROLINA...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLGT RISK AREA...

...SUMMARY...
A few strong to severe thunderstorms may linger over the next couple
of hours from parts of the Delmarva Peninsula southwest into central
North Carolina.

...Discussion...
Thunderstorms continue to gradually decrease in intensity and/or
move offshore from New England southwest to the mid-Atlantic region
this evening. Meanwhile, storms persist within a band from the
Carolinas west-southwest across the lower Mississippi Valley area.
While an isolated/briefly severe storm could occur within this
entire area over the next couple of hours, the main severe risk
appears to linger from Delaware southwest into central North
Carolina. Here, evening RAOBs depict a moist/unstable airmass,
which will support continuation of thunderstorms over the next
several hours. While continued/modest low-level cooling will
contribute to a gradual decrease in storm intensity,
offsetting/ample shear suggests risk for locally damaging winds
and/or hail continuing for another roughly 2-3 hours.

..Goss.. 06/20/2017

Próxima actualización: 06:00z.
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mar Jun 20, 2017 6:16 pm

Varias zonas con riesgo marginal y leve. Habrá que seguir lo que pueda pasar en el sur de Lousiana y de Mississippi, que por el acercamiento de la tormenta tropical Cindy, pueden tener algunos tornados aislados.
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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
0252 PM CDT Tue Jun 20 2017

Valid 202000Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
KS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
SOUTHERN LA/MS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS TO THE DESERT SOUTHWEST...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
IL/IN...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE NORTHERN GREAT BASIN INTO THE NORTHERN PLAINS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE CENTRAL GULF COAST REGION...

...SUMMARY...
Severe thunderstorms are expected this afternoon and evening over
parts of the central Plains. A few tornadoes may occur this
afternoon through tonight over the central Gulf Coast. Isolated
severe storms also are possible over parts of Illinois and the mid
Mississippi Valley, as well as from the northern Rockies and High
Plains into South Dakota and from portions of the southern Rockies
vicinity to the Desert Southwest.

...Discussion...
Aside from a minor eastward expansion to the Slight Risk area across
parts of central KS where steepening low-level lapse rates are
contributing to sufficient buoyancy to support severe hail/wind
potential with developing clusters of thunderstorms, no additional
substantial changes have been made to the ongoing forecast.

..Cohen.. 06/20/2017

.PREV DISCUSSION... /ISSUED 1124 AM CDT Tue Jun 20 2017/

...KS...
Southwesterly low-level winds are helping to transport rich low
level moisture back into KS today, with dewpoints rising through the
60s. By mid/late afternoon, strong CAPE values are forecast to
develop, leading to the development of scattered thunderstorms.
Favorably strong northwesterly flow aloft will promote supercell
structures capable of large hail and damaging wind gusts. The
primary severe risk should remain well-focused in west-central and
western KS as the low-level jet strengthens this evening.

...LA/MS Coast...
PTC #3 continues to slowly organize in the central Gulf of Mexico.
as the circulation drifts northwestward, and low-level winds
strengthen in the northeast quadrant of the circulation, the
potential for a few rotating cells and isolated tornadoes will
increase. Current indications are the best chance of tornadoes will
be this evening across parts of southern LA and the immediate MS
coast.

...IL/IN...
Water vapor loop shows a fast-moving upper trough tracking
southeastward across MN/WI. This feature will promote scattered
thunderstorm development this afternoon over parts of northern and
central IL. Storms will also eventually spread into parts of IN.
Vertical shear profiles are quite favorable for severe storms.
However, forecast soundings show that unstable layer will be
relatively shallow due to a large mid/upper level inversion across
the region. The stronger cells may produce gusty/damaging winds and
hail, but the complex thermodynamic structure limits confidence in a
greater severe threat.

...MT/WY/SD...
A few thunderstorms are expected to develop over the mountains of
southwest and southern MT today, and spread east-southeastward into
parts of northern WY and eventually into western SD. The strongest
of these storms may produce hail and gusty winds.

...Eastern ID/Western WY into Northern UT...
Widely scattered high-based thunderstorms are expected to develop
over parts of eastern ID and northwest UT this afternoon, spreading
eastward across the MRGL risk area. Forecast soundings suggest the
potential for strong downdrafts in the more robust cells.

Próxima actualización: 01:00z.
---------------------------------------------------------------------
Watch vigente.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 357
NWS Storm Prediction Center Norman OK
155 PM CDT Tue Jun 20 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Western and Central Kansas

* Effective this Tuesday afternoon and evening from 155 PM until
900 PM CDT.

* Primary threats include...
Scattered large hail likely with isolated very large hail events
to 2.5 inches in diameter possible
Scattered damaging wind gusts to 70 mph likely

SUMMARY...Scattered intense thunderstorms are expected to form
across the watch area this afternoon. These storms will drift
slowly southeastward, posing a risk of large hail and damaging wind
gusts.

The severe thunderstorm watch area is approximately along and 65
statute miles north and south of a line from 45 miles northwest of
Garden City KS to 35 miles east of Salina 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.

&&

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 500. Mean storm motion vector
29025.

...Hart

---------------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1099
NWS Storm Prediction Center Norman OK
1259 PM CDT Tue Jun 20 2017

Areas affected...Parts of northwestern/central Kansas and adjacent
southern Nebraska

Concerning...Severe potential...Watch possible

Valid 201759Z - 202000Z

Probability of Watch Issuance...60 percent

SUMMARY...Isolated to scattered rapid severe storm development
appears possible as early as 19-21Z, with large hail the primary
initial severe threat. Strong surface gusts may become an
increasing concern near storms later this afternoon. Trends are
being monitored for the possibility of a severe weather watch.

DISCUSSION...Surface heating along/west of a corridor of boundary
layer moisture return across the Liberal/Dodge City areas,
northeastward through Russell/Hill City, has already contributed to
strong potential instability. This is occurring beneath steepening
mid-level lapse rates associated with the leading edge of elevated
mixed layer air beginning to return eastward across the high Plains.
In the presence of generally weak but veering winds with height,
beneath 30-40 kt northwesterly flow around 500 mb, the environment
appears conditionally supportive of organized severe storm
development, including supercells.

Although the Rapid Refresh suggests that mid-level inhibition is
weakening with continuing insolation, this probably is being offset,
at least somewhat, by gradual warming aloft. Still, large-scale
ascent associated with lower/mid tropospheric warm advection could
support the initiation of thunderstorms. And there appears a
general consensus among various model output that this may occur as
early as 19-21Z, roughly centered around the Russell/Hill City area.
Once initiation of deep convection commences, fairly rapid
intensification appears possible, accompanied by a risk for severe
hail, some of which could be very large.

..Kerr/Hart.. 06/20/2017

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Mesoscale Discussion 1100
NWS Storm Prediction Center Norman OK
0200 PM CDT Tue Jun 20 2017

Areas affected...Parts of southeast Colorado...northeastern New
Mexico and the TX/OK panhandle region

Concerning...Severe potential...Watch unlikely

Valid 201900Z - 202130Z

Probability of Watch Issuance...20 percent

SUMMARY...Vigorous thunderstorm activity, perhaps including an
isolated supercell or two, may be accompanied by at least some risk
for severe wind and hail late this afternoon. It is not clear that
a watch is needed, but trends will continue to be monitored.

DISCUSSION...Deepening convective development is now evident along
the eastern slopes of the Sangre de Cristo Mountains, in response to
daytime heating. This is occurring in the presence of generally
light westerly to northwesterly deep layer mean flow, which will
eventually support a propagation off the higher terrain into an
environment across the adjacent high plains that now appears
characterized by strong potential instability.

Despite the weak wind fields, the latest Rapid Refresh suggests that
veering with height may be contributing to localized vertical shear
at least marginally sufficient for supercell structures, mainly near
and southeast of the Raton Mesa area, where there appears at least
some risk for severe hail. Otherwise, localized strong downbursts
may be the primary threat, with activity becoming rooted in a
strongly heated and deeply mixed boundary layer.

..Kerr/Hart.. 06/20/2017

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Mesoscale Discussion 1101
NWS Storm Prediction Center Norman OK
0205 PM CDT Tue Jun 20 2017

Areas affected...Portions of far eastern IA...northern/central
IL...and northwestern IN

Concerning...Severe potential...Watch unlikely

Valid 201905Z - 202130Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated large hail and damaging wind threat may
develop this afternoon. Watch issuance is unlikely.

DISCUSSION...A shortwave trough over WI is embedded within
large-scale troughing over much of the eastern CONUS. Ascent
associated with this shortwave trough is encouraging convective
development along a surface front located across central/eastern IA
into northern IL as of 19Z. Although low-level moisture remains
limited across northern/central IL and vicinity, it should prove
sufficient in combination with strong diurnal heating to maintain
convection as it moves quickly southeastward through the remainder
of the afternoon and into this evening. Southwesterly low-level
winds both strengthen and veer to northwesterly with height, and
resultant effective bulk shear values of 40-50 kt will support
organized updrafts.

Instability should remain limited to around 500-1000 J/kg through
peak heating, mainly owing to warm mid-level temperatures centered
around 500 mb per 12Z soundings from DVN and ILX. But, steep low and
mid-level lapse rates below 500 mb should enhance convective
downdrafts, with an isolated strong to locally damaging wind threat
possible with expected scattered thunderstorms. A few instances of
marginally severe hail may also occur. The previously mentioned warm
mid-level temperatures may limit more robust updraft intensities,
and the corresponding severe threat will probably remain too
isolated/marginal to warrant a watch.

..Gleason/Hart.. 06/20/2017

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Mesoscale Discussion 1102
NWS Storm Prediction Center Norman OK
0340 PM CDT Tue Jun 20 2017

Areas affected...Parts of western and central Kansas

Concerning...Severe Thunderstorm Watch 357...

Valid 202040Z - 202245Z

The severe weather threat for Severe Thunderstorm Watch 357
continues.

SUMMARY...Thunderstorm development accompanied by increasing risk
for severe hail and wind expected across parts of western/central
Kansas through early evening.

DISCUSSION...Vigorous convective development is now well underway,
with storms beginning to increase in number near/west and southwest
of the Hill City area. In the presence of large CAPE (on the order
of 2000-3000 J/kg), strong vertical shear, and at least weak
lower/mid tropospheric warm advection, considerable further
intensification and upscale convective growth appears possible
through 22-00Z.

The risk for severe hail will persist in strongest cells, and
locally strong downbursts are expected to become an increasing
threat in the presence of the strongly heated (surface temps in the
mid/upper 90s F) and deeply mixed boundary layer. Eventually, cold
pool consolidation and strengthening may coincide with the evolution
of an organized mesoscale convective system by this evening, which
should tend to forward propagate eastward/southward, perhaps
accompanied by an increasing areal risk for strong, potentially
damaging wind gusts.

..Kerr.. 06/20/2017
Dome, dome, dome..The life is a dome

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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mar Jun 20, 2017 11:40 pm

Nueva actualización del SPC. 2 zonas con riesgo leve. Una de ellas(la del sur de Louisiana y el extremo sur de Mississippi), está asociada a la TTCindy, zona donde se pueden dar algunos tornados aislados.
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% de tornados.
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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
0811 PM CDT Tue Jun 20 2017

Valid 210100Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE WESTERN AND CENTRAL KANSAS VICINITY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
SOUTHEAST LOUISIANA EASTWARD TO THE MOBILE BAY VICINITY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
KANSAS SLGT RISK...AND EXTENDING SOUTHWESTWARD TO SOUTHEAST
ARIZONA...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
GULF COAST SLIGHT RISK...FROM SOUTHERN LOUISIANA TO THE FLORIDA
PANHANDLE...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN
UTAH AND SOUTHEAST IDAHO EAST ACROSS SOUTHERN MONTANA/NORTHERN
WYOMING INTO SOUTH DAKOTA...

...SUMMARY...
Severe thunderstorms will continue this evening over parts of the
western and central Kansas vicinity, with a more isolated risk
extending southwest across New Mexico and into southeast Arizona. A
couple of tornadoes may occur this evening and overnight over the
central Gulf Coast area. An isolated strong/severe storm or two may
also occur from the northern Rockies and High Plains into South
Dakota.

...Central and western Kansas and vicinity...
A few strong/locally severe storms are ongoing across parts of
western and central Kansas and into far south-central Nebraska,
where a moderately unstable airmass (mixed-layer CAPE in the 2000 to
2500 J/kg range) resides per evening RAOBs and objective analyses.
With moderate mid-level northwest flow atop low-level
southeasterlies providing ample shear for organized/rotating
updrafts, potential for hail and locally damaging winds will
continue over the next few hours before gradually diminishing as the
boundary layer cools/stabilizes.

...the Central Gulf Coast region...
Widespread precipitation is occurring across the central and eastern
Gulf Coastal areas surrounding T.S. Cindy, as the center of the
storm continues moving slowly northwestward across the north-central
Gulf. A few cells in the Florida Panhandle have shown some
rotation, and expect additional convection moving onshore to pose
isolated/brief tornado risk into the overnight hours, given
favorably strong low-level shear.

...Parts of the Intermountain West into South Dakota...
Showers and scattered thunderstorms continue across parts of the
Intermountain West, with the most vigorous storms at this time over
northern Utah, and across the Montana/Wyoming border region where an
ample CAPE/shear environment exists. Though storms should gradually
diminish in intensity this evening, a isolated storm or two capable
of producing damaging winds or marginal hail may occur over the next
couple of hours. Farther east, elevated storms may spread/develop
eastward into parts of South Dakota overnight, aided by ascent
associated with a developing/southerly low-level jet. While
instability should remain somewhat limited, marginal hail may occur
with one or two of the strongest storms.

..Goss.. 06/21/2017

Próxima actualización: 06:00z.
--------------------------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1103
NWS Storm Prediction Center Norman OK
0618 PM CDT Tue Jun 20 2017

Areas affected...Central and western Kansas into far southeast
Colorado

Concerning...Severe Thunderstorm Watch 357...

Valid 202318Z - 210115Z

The severe weather threat for Severe Thunderstorm Watch 357
continues.

SUMMARY...Large hail remains likely mainly over western Kansas and
into far southeastern Colorado, with isolated damaging wind gusts.
Isolated hail may eventually spread eastward across north central
Kansas.

DISCUSSION...Numerous storms are currently ongoing across western
KS, with several strong to severe also extending southwestward into
southeast CO. Veering winds in the low-levels beneath northwest flow
aloft will continue to support mainly southward-moving cells, with
some supercell potential resulting in large hail and strong wind
gusts. New cell generation has been noted recently over northwest
Kansas, but these cells are unlikely to pose more than a marginal
threat due to outflow to the south.

A few of the storms near Hays/Russell are merging and may post a
wind/hail threat across central KS. However, the far eastern rows of
counties including the I-35 corridor, and south-central KS may not
see much storm activity due to increasing CIN this evening.
Therefore, it is possible that extreme eastern portions of the watch
may be canceled early.

..Jewell.. 06/20/2017

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Mesoscale Discussion 1104
NWS Storm Prediction Center Norman OK
0815 PM CDT Tue Jun 20 2017

Areas affected...Coastal areas of Mississippi...Alabama...and the
Florida Panhandle

Concerning...Severe potential...Watch unlikely

Valid 210115Z - 210345Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated tornado threat will evolve with isolated
convection across the discussion area over the next couple of hours,
with a more appreciable tornado threat potentially evolving
overnight.

DISCUSSION...Scattered banded and cellular convective structures
have evolved in the northeastern quadrant of T.S. Cindy. A couple
of these storms have exhibited rotation near/north of Apalachicola,
FL, while other storms offshore are exhibiting rotation and may
threaten coastal areas from Mobile, AL eastward to Fort Walton, FL
over the next couple of hours. Low-level shear has gradually
increased throughout the day in response to strengthening easterly
low-level flow associated with Cindy. Instability is negligible in
most areas, but increases along and south of an east-west-oriented
baroclinic zone from near Plaquemines Parish, LA eastward to near
Tallahassee, FL. As this zone shifts northward with time, the
tornado threat will increase as rotating cells migrate inland from
open waters. The threat in the near term is too isolated to warrant
a tornado watch issuance, although this area will be monitored into
the overnight hours as instability increases across the region.

..Cook/Guyer.. 06/21/2017
Dome, dome, dome..The life is a dome

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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mié Jun 21, 2017 11:26 am

Nuevo día de tiempo severo en los Estados Unidos, con todos los riesgos asociados. La chance de tornados, la sigue teniendo la costa sur.
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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
0755 AM CDT Wed Jun 21 2017

Valid 211300Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN
TEXAS PANHANDLE TO PARTS OF MINNESOTA AND WISCONSIN...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
LOUISIANA TO THE WESTERN FLORIDA PANHANDLE...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
CENTRAL PLAINS/UPPER MIDWEST SLIGHT RISK...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
GULF STATES SLIGHT RISK...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE UPPER OHIO VALLEY TO SOUTHERN NEW ENGLAND...

...SUMMARY...
Severe thunderstorms are possible from parts of the southern High
Plains to the north-central states for Wednesday into Wednesday
night, with the greatest severe thunderstorm potential from parts of
the Texas and Oklahoma Panhandles northeastward to Minnesota and
Wisconsin. Also, a tornado risk will exist in portions of the
north-central Gulf Coast region.

...Synopsis...
The basic mid/upper-level pattern will be characterized by:
* A nearly zonal northern stream from the northern Rockies and High
Plains to New England;
* An intense but slowly weakening ridge across the Southwest
* Tropical Storm Cindy and the associated height weakness over the
west-central Gulf States.

A 500-mb cyclone north of the aforementioned northern-stream flow
belt was evident in moisture-channel imagery over northern AB. As
this feature migrates eastward across the northern Prairie Provinces
through the period, a series of shortwave troughs will traverse the
gently cyclonic flow to its south, leading with a trough now located
in western SK.

At the surface, a warm front was drawn at 11Z from northern KY
across western IL to southwestern IA, then to a weak/diffuse low
located near the Pine Ridge area of the Nebraska/South Dakota
border. A surface trough extended from there southwestward to
northern CO, with a diffuse cold front farther north across the
northern High Plains. The low should shift eastward to the FSD/SUX
region by 00Z, with warm front southeastward over southern IN and
trough southwestward across western KS to southeastern CO.
Overnight, the low should move eastward across southern WI, with
cold front west-southwestward to southern WY, and the trough
reforming in a meridional configuration over western portions of
KS/NE. Meanwhile, a marine/warm front was drawn close to the
LA/MS/AL/western FL Panhandle coast, in Cindy's northeastern sector.
Slow northward movement of this boundary is expected through the
period, made gradual and erratic by stabilization from prolonged
precip areas inland.

...Upper Midwest to central High Plains...
Widely scattered to scattered thunderstorms are forecast to develop
this afternoon in a southwest/northeast-oriented band along the
trough, from western KS at least into parts of southern and eastern
NE. The earliest and perhaps most dense zone of convective
development may be over KS and southern NE where strongest diurnal
heating and lift along the trough will combine to remove MLCINH.
Forecast soundings across this area show a hot, well-mixed subcloud
layer with very steep low/middle-level lapse rates, within a narrow
corridor of low/mid 60s F surface dew points, supporting 2000-3000
J/kg MLCAPE.

Coverage will be limited with southwestward extent by the prevalence
of drier air and deeper mixing. Meanwhile, EML-related capping may
restrict coverage farther north in the richer, evapotranspiratively
aided surface moisture of northeastern NE and southeastern SD. In
terms of parameter space favorable for supercells with large/
damaging hail and perhaps a tornado, the area near the junction of
the trough and warm front still appears to be the most favorable,
with lower LCL than farther southwest and MLCAPE in the 3000-4500
J/kg range, and warm-frontal effective SRH 150-300 J/kg. However,
considerable uncertainty exists on whether sufficient local-scale
lift will occur on either boundary to support storm(s) in this
environment during the day or earliest evening, while
effective-inflow parcels still are surface-based. A continuation of
the northern part of the Plains convective corridor, and/or
additional thunderstorms, may occur tonight from eastern NE across
IA, offering primarily a large-hail threat.

Additional, elevated thunderstorms may develop over parts of SD
overnight -- likely after 06Z -- as colder air aloft and increasing
large-scale lift begins to overlie favorable low-level theta-e.
Steep lapse rates aloft and moistening in an inflow layer around
700-750 mb contribute to MUCAPE near 1000 J/kg in forecast
soundings, with effective-shear magnitudes 40-50 kt, in support of
isolated hail potential. Strong/isolated severe gusts cannot be
ruled out as well, despite relatively stable surface conditions,
given a relatively dry subcloud layer.

...central Gulf Coast and lower Delta region...
Tropical Storm Cindy continues its northwestward progress toward a
central landfall near the BPT area, per NHC forecasts. A broad area
of favorable low-level wind fields and enlarged hodographs will
extend well northeast and east of center throughout the period, with
low-level shear values and hodographs likely smaller near center
that farther out. This kinematic regime should shift inland nearly
in step with the translational vector of the system as a whole. The
buoyancy part of the favorable CAPE/shear parameter space, as often
is the case with cyclones of this configuration, will lag the
optimal low-level shear, given the extensive and long lived precip
area inland, and its tempering of favorable destabilization.
Nevertheless, as the warm-frontal zone shifts northward, at least
marginally favorable instability will arise from a combination of:
1. Pockets of relatively maximized surface heating rimming the
midlevel dry slot(s) evident in IR and moisture-channel satellite
imagery, and
2. Low-level theta-e advection from a Gulf boundary layer that has
been less disrupted convectively.
Tornado potential may be maximized locally where relatively
sustained discrete cells moving northwestward, and/or spiral
convergence bands, cross the region of backed surface winds and
larger hodographs in the warm-frontal zone, thereby passing through
a buoyancy/shear overlapping regime.

For more on the near-term tornado threat, refer to SPC tornado watch
358 and related mesoscale discussions. See the latest NHC
advisories for track/intensity forecasts and tropical
watches/warnings related to Cindy.

...Upper Ohio Valley to southern New England...
Widely scattered thunderstorms should move generally eastward across
this corridor from midday through afternoon, offering isolated
damaging gusts. Diabatic surface heating, in the presence of
surface dew points generally mid 50s to near 60 F, will steepen
boundary-layer and deep-layer lapse rates, while weakening MLCINH
and boosting MLCAPE to 300-800 J/kg. Nearly unidirectional deep-
layer wind profiles, strong speed shear and elongated hodographs
indicate the potential for a few organized thunderstorms with peak
gusts near severe limits and capable of tree damage. This threat
should diminish markedly after dark as the boundary layer cools.

..Edwards/Picca.. 06/21/2017

Próxima actualización: 16:30z.
------------------------------------------------------------------
Watch vigente.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 358
NWS Storm Prediction Center Norman OK
1020 PM CDT Tue Jun 20 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Southern Alabama
Florida Panhandle
Southern Louisiana
Southern Mississippi
Coastal Waters

* Effective this Tuesday night and Wednesday morning from 1020 PM
until 1000 AM CDT.

* Primary threats include...
A few tornadoes possible

SUMMARY...A strong low/mid-level wind field on the periphery of
Tropical Storm Cindy, in conjunction with an increasingly moist
maritime air mass (75+ F surface dewpoints), will support an
increasing risk for tornadoes through the overnight and early
morning hours of Wednesday.

The tornado watch area is approximately along and 50 statute miles
north and south of a line from 50 miles west northwest of Houma LA
to 40 miles south southeast of Marianna FL. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU8).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and 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.

&&

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 15020.

...Guyer

------------------------------------
Últimas discusiones a mesoecala.
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Mesoscale Discussion 1105
NWS Storm Prediction Center Norman OK
0948 PM CDT Tue Jun 20 2017

Areas affected...Coastal areas of
Louisiana...Mississippi...Alabama...and the Florida Panhandle

Concerning...Severe potential...Watch possible

Valid 210248Z - 210345Z

Probability of Watch Issuance...60 percent

SUMMARY...A recent uptick in convection has occurred over the past
hour over coastal waters, with convection expected to eventually
migrate inland. A tornado watch is being considered.

DISCUSSION...Scattered convection has increased in coverage and
intensity over the past half hour, although this uptick has occurred
primarily over open coastal waters from near the Chandeleur Islands
eastward to areas near/south of Apalachicola, FL. The greatest
instability (boosted by mid/upper 70s F dewpoints) remains offshore,
although some of the more unstable air has worked its way
northwestward into far southeastern Louisiana, where objective
analyses indicate nearly 1000 J/kg MUCAPE amidst 77-80 F dewpoints.
These higher dewpoints will advect northward gradually, with an
increase in the potential for low-level mesocyclones and tornadoes
gradually increasing in the discussion area in conjunction with the
slightly greater destabilization.

With these factors in mind, a tornado watch is being considered over
the next hour or so.

..Cook/Guyer.. 06/21/2017

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Mesoscale Discussion 1106
NWS Storm Prediction Center Norman OK
0212 AM CDT Wed Jun 21 2017

Areas affected...Portions of the central Gulf Coast

Concerning...Tornado Watch 358...

Valid 210712Z - 210915Z

CORRECTED FOR WATCH TYPE

The severe weather threat for Tornado Watch 358 continues.

SUMMARY...The threat for a few tornadoes along the central Gulf
Coast should continue to slowly increase towards daybreak.

DISCUSSION...As Tropical Storm Cindy continues its slow
northwestward movement, a broad area of showers and thunderstorms
has advanced near/onshore from Louisiana eastward to the Florida
Panhandle. Several convective cells (primarily those offshore)
within this regime have exhibited low-level rotation, with
occasional waterspouts probable in several of these offshore cells.
Regional VWP data (e.g., KLIX, KMOB, KEVX) sample low-level winds
strongly veering with height, bolstering storm-relative helicity and
the potential for low-level mesocyclogenesis. Additionally, this
notable veering implies considerable warm-air advection near a front
stretching from Plaquemines Parish east/northeastward to the Florida
Panhandle. Near and to the south of this boundary, dew points in the
mid/upper 70s and temperatures in the upper 70s/lower 80s are
offering adequate surface-based buoyancy for a tornadic threat.

VWP data, model analyses, and surface pressure-fall observations
indicate the strongest branch of the low-level jet currently resides
from the Alabama Panhandle southeastward into the Gulf. Indeed,
radar data indicate a band of strong thunderstorms extending
near/along this axis, likely fostered by warm-air advection and
speed convergence near the coast. While these cells are currently
displaced from zones of sufficient onshore destabilization (i.e.,
Plaquemines Parish, LA and the Apalachicola, FL vicinity), continued
northward advection of warm/moist air will likely increase the
tornado threat from southern Mississippi to the western Florida
Panhandle over the next several hours. Farther west, water-vapor
imagery and forecast soundings suggest drying aloft is leading to
shallower/more sparse convection across southeast Louisiana.
However, further surface destabilization and favorable
storm-relative helicity will maintain some tornado threat here as
well through the night.

..Picca.. 06/21/2017

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Mesoscale Discussion 1107
NWS Storm Prediction Center Norman OK
0747 AM CDT Wed Jun 21 2017

Areas affected...Portions of the central Gulf Coast

Concerning...Tornado Watch 358...

Valid 211247Z - 211445Z

The severe weather threat for Tornado Watch 358 continues.

SUMMARY...The threat for a few tornadoes near the coast continues
this morning. Additionally, new watch issuance may be required prior
to the 15Z (10AM CDT) expiration of Watch 358.

DISCUSSION...Although the center of Tropical Storm Cindy is
progressing farther away from the ongoing Tornado Watch, conditions
remain modestly favorable for a few brief tornadoes this morning.
Very slow northward movement of a warm front overnight has brought
weak, but adequate surface-based buoyancy to parts of the central
Gulf Coast. Combined with enhanced storm-relative helicity (noted
most clearly in recent KMOB VWP data and the 12Z LIX sounding),
low-level mesocyclones will likely persist in semi-discrete/cluster
modes within confluent bands approaching the coast. Indeed, KEVX
data likely detected a tornado near Fort Walton Beach, FL via a
dual-pol debris signature around 1120Z (620AM EDT).

Persistent moist south/southeasterly flow and pockets of weak
diurnal heating will lead to further inland advancement of
sufficient surface-based buoyancy this morning. However, the
low-level jet peripheral to Cindy will evolve westward through the
day, likely shifting the highest tornado threat closer to the
Mississippi River. While mid-level drying over this part of the
watch has kept convection shallower and more sparse in coverage so
far, the westward evolution of the low-level jet (and related warm
advection) today will likely combine with further destabilization to
foster renewed convection along one or more confluence bands from
Alabama to Louisiana. Recent visible satellite/lightning data
suggest the initial stages of this evolution may be underway across
the central Gulf. Considering the aforementioned environmental
parameters, storms approaching the coast later this morning may
still yield an increased tornado threat. Therefore, a new watch may
be coordinated within the next two hours.

..Picca.. 06/21/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Jue Jun 22, 2017 7:36 pm

Y vamos con otro día de tiempo severo por el sur y en zonas del medio oeste. Todos los riegos asociados(el de tornados aislados, abarca el sur solamente).
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% de tornados.
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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
0250 PM CDT Thu Jun 22 2017

Valid 222000Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF THE CENTRAL GULF COAST
STATES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS...AND WITHIN A CORRIDOR ACROSS THE MID
MISSOURI VALLEY THROUGH THE SOUTHERN GREAT LAKES REGION...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
GULF COAST SLIGHT RISK AREA...INTO PORTIONS OF THE MID SOUTH...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS AREAS
SURROUNDING THE SLIGHT RISK ACROSS THE CENTRAL PLAINS AND MID
MISSOURI VALLEY INTO THE GREAT LAKES REGION...

...SUMMARY...
Thunderstorm activity, potentially capable of producing localized
damaging wind gusts and a couple of tornadoes, will persist across
parts of the central Gulf States into the Mid South late this
afternoon and evening. Other widely scattered strong to severe
storm development is possible in a corridor from the central high
Plains through the mid Missouri Valley and southern portions of the
Great Lakes region.

...20Z Outlook Update...
The general idea of the preceding outlooks remains largely
unchanged. However, adjustments have been made to the categorical
and probabilistic lines to account for ongoing trends, and attempt
to better define areas of severe weather potential for late this
afternoon and evening. Higher (slight risk) severe probabilities
east northeast of the central high Plains are generally focused
within the narrow corridor of stronger boundary layer heating now
taking place just ahead of the cold front from the central
Plains/mid Missouri Valley into the upper Great Lakes region, and
along/south of a remnant outflow boundary across parts of the Upper
Midwest. This is mostly south of the strongest westerlies, but
shear on the southern fringe of the westerlies, coupled with
thermodynamic profiles characterized by relatively steep mid-level
lapse rates and moderate CAPE, appears to provide an environment
conducive to strong/severe storm development. For more specific
details concerning ongoing or more imminent severe weather
potential, please refer to the latest SPC mesoscale discussions.

..Kerr.. 06/22/2017

.PREV DISCUSSION... /ISSUED 1143 AM CDT Thu Jun 22 2017/

...Gulf Coast States/lower MS Valley into TN Valley...
Tropical Depression Cindy, centered over far west-central LA as of
mid/late morning, is expected to continue to drift slowly
north-northeastward through the afternoon into tonight. Even while
the system may begin to fill with a tendency for a weakening surface
low, strong low/mid-level southerly winds on the eastern periphery
of the system will continue to yield the possibility of low-topped
supercells and at least some tornado risk over a relatively broad
area of the region. A few weakly rotating cells have been noted this
morning across the western FL Panhandle as well as southeast LA into
southern MS, and this same scenario/supportive environment should
somewhat expand north-northwestward through the afternoon and
evening. The overall tornado risk, which appears relatively modest
overall across a broad region, should diurnally peak this afternoon
into early/mid-evening, although some tornado risk could continue
into the overnight and early morning hours of Friday.

...CO/WY Front Range and Central/southern High Plains...
Isolated high-based storms are expected to develop by late afternoon
along the south/southeastward-moving front spanning portions of KS
into southeast NE. Where storms develop, moderate amounts of
CAPE/vertical shear will allow for semi-organized clusters of storms
capable of isolated large hail aside from a locally damaging wind
risk with outflow dominant convection.

Other storms are likely to develop this afternoon within an evolving
post-frontal upslope flow regime, with initial development along and
just east of the CO/southeast WY Front Range. As an increasingly
moist environment develops into the region and the boundary layer
destabilizes, relatively long/straight hodographs will support the
possibility of splitting supercells capable of large hail.
Severe-caliber wind gusts will also possible given relatively
deep/well-mixed sub-cloud layers.

...Upper Midwest/Great Lakes...
Ahead of a southeastward-moving cold front, a fast-moving cluster of
storms will continue eastward from southeast MN into southern WI
today to the north of an outflow boundary and weakening convection
across eastern IA/far southern WI and far northern IL. Widespread
cloudiness across WI to the north of the outflow boundary should
largely curb surface-based severe potential, with storms otherwise
likely to develop by mid/late afternoon along the
southeastward-moving front across IA and possibly into far southeast
MN/southwest WI. While the strongest winds aloft will tend to lag
(to the west/northwest) the cold front, sufficient vertical shear
(30-40 kt) in the presence of moderate buoyancy (generally 1500-2500
J/kg MLCAPE) will yield multicells and some supercells capable of
large hail and damaging winds especially late this afternoon into
evening.

Próxima actualización: 01:00z.
----------------------------------------------------------------------------------
Watch vigente.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 364
NWS Storm Prediction Center Norman OK
105 PM CDT Thu Jun 22 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Alabama
Southeast Arkansas
Eastern and southern Louisiana
Mississippi
Coastal Waters

* Effective this Thursday afternoon and evening from 105 PM until
1000 PM CDT.

* Primary threats include...
A few tornadoes possible

SUMMARY...On the eastern periphery of slow-northward-moving Tropical
Depression Cindy, a moist environment coupled with moderately strong
low-level shear will support the possibility of a few tornadoes this
afternoon into evening.

The tornado watch area is approximately along and 115 statute miles
north and south of a line from 20 miles northwest of Natchez MS to
30 miles northeast of Montgomery AL. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU4).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and 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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 363...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 18035.

...Guyer

--------------------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1108
NWS Storm Prediction Center Norman OK
0138 PM CDT Wed Jun 21 2017

Areas affected...Portions of central/southern PA...MD...far eastern
WV...DC...far northern VA...DE...NJ...southern NY...and CT

Concerning...Severe potential...Watch unlikely

Valid 211838Z - 212115Z

Probability of Watch Issuance...5 percent

SUMMARY...Strong/gusty winds associated with isolated thunderstorms
this afternoon may produce sporadic tree damage. A watch is not
anticipated for this marginal severe threat.

DISCUSSION...Isolated thunderstorms have developed over the past
hour or so along a remnant front across central PA. Visible
satellite imagery shows partly to mostly sunny conditions to the
east of this isolated convection (across eastern PA/northern NJ into
southern NY/CT), and surface temperatures have generally warmed into
the 80s away from the coast. Although the low-level airmass is not
overly moist along/south of the remnant front per area 18Z surface
observations and 12Z soundings, it is sufficient to support weak
instability of generally 250-750 J/kg (MLCAPE). Some additional
diurnal heating through late afternoon may locally boost MLCAPE to
around 1000 J/kg.

Recent VWPs from KCCX depict nearly unidirectional westerly flow
strengthening quickly to around 45-50 kt at 5 km, and the
mid/upper-level flow likely increases further through the remainder
of the troposphere given the presence of a belt of enhanced flow
over this region per latest short-term guidance and water vapor
satellite imagery. Related effective bulk shear of 40-50 kt should
support some convective organization even with instability expected
to remain modest owing mainly to poor mid-level lapse rates.
Steepening low-level lapse rates owing to continued diurnal heating
combined with the strong shear may result in an isolated
strong/gusty convective downdraft wind risk. However, nebulous
large-scale forcing for ascent, weak instability, and generally
isolated thunderstorm coverage will likely keep the overall severe
threat marginal. Therefore, watch issuance is not expected at this
time.

..Gleason/Weiss.. 06/21/2017

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Mesoscale Discussion 1109
NWS Storm Prediction Center Norman OK
0230 PM CDT Wed Jun 21 2017

Areas affected...Parts of south central Nebraska...western
Kansas...southeastern Colorado..northeast New Mexico and adjacent
portions of the high Plains

Concerning...Severe potential...Watch possible

Valid 211930Z - 212130Z

Probability of Watch Issuance...40 percent

SUMMARY...Increasing thunderstorm activity is expected to be
accompanied by a risk for severe hail and winds late this afternoon
and evening. While the potential for the evolution of an
appreciable organized convective system seems relatively low, it is
possible the the severe weather threat could require a watch at some
point late this afternoon.

DISCUSSION...Scattered thunderstorms appear to be in the process of
initiating across the central/southern high Plains region, from the
eastern and southern slopes of the Sangre De Cristo Mountains/Palmer
Divide vicinity northeastward into southwestern Nebraska. This
appears to be occurring within the lee surface trough, where modest
boundary layer moisture lingers and is contributing sizable CAPE in
the presence of strong surface heating (temps now in the mid/upper
90s). With further boundary layer heating/mixing, activity is
expected to continue to gradually intensify and increase in
coverage, perhaps aided by forcing associated with a weak upper
impulse or two digging southeastward, and around the northeastern
periphery of the southwestern subtropical high.

With thermodynamic profiles becoming characterized by a hot and
deeply mixed boundary layer, with steep mid-level lapse rates and
CAPE on the order of 2000+ J/kg, the environment appears conducive
to at least some risk for severe hail initially. This should be
followed by increasing potential for localized strong downbursts
later this afternoon, as light westerly/northwesterly deep layer
mean flow supports a southeastward propagation across the high
Plains through early evening.

..Kerr/Weiss.. 06/21/2017

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Mesoscale Discussion 1110
NWS Storm Prediction Center Norman OK
0335 PM CDT Wed Jun 21 2017

Areas affected...Portions of eastern ND...northeastern SD...and
western/central MN

Concerning...Severe potential...Watch possible

Valid 212035Z - 212300Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated large hail and damaging winds may occur with
thunderstorms expected to develop later this afternoon/early
evening. Watch issuance is possible.

DISCUSSION...20Z surface observations indicate a weak cold
front/wind shift extending from southern Manitoba into eastern ND,
and continuing southwestward across SD. A warm front is located
north/south along the ND/MN border, continuing into southwestern MN
and IA. As an upper low pivots eastward across
Saskatchewan/Manitoba, increasing (50-70+ kt) mid-level westerly
flow is beginning to overspread the Dakotas and western MN.
Large-scale ascent attendant to this mid-level jet will likely
foster convective initiation along the cold front in eastern ND and
perhaps northeastern SD over the next several hours. This activity
would then develop eastward into western/central MN through the
evening.

As of 2030Z, the low-level airmass has destabilized in a narrow
corridor between the cold/warm fronts. There is some potential for
the warm front to shift eastward into more of western/central MN
over the next several hours as southerly low-level flow strengthens
across this region in the wake of morning convection. Low-level
moisture characterized by surface dewpoints in the upper 50s to mid
60s across the warm sector remains somewhat of a limiting factor, as
MLCAPE should generally increase to no more than 1000-1500 J/kg
immediately ahead of the cold front.

However, strong 40-55+ kt of effective bulk shear will likely
support supercells with initial development, and both large hail and
damaging winds may occur. Some potential for upscale growth into one
or more bowing line segments may take place with the front acting as
a linear forcing mechanism. A tornado or two may also occur with any
discrete convection crossing the warm front where low-level flow may
be locally backed to southeasterly. Radar and observational trends
will be monitored through the remainder of the afternoon/early
evening for possible watch issuance.

..Gleason/Weiss.. 06/21/2017

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Mesoscale Discussion 1111
NWS Storm Prediction Center Norman OK
0342 PM CDT Wed Jun 21 2017

Areas affected...Parts of southern Louisiana/Mississippi/Alabama and
the western Florida panhandle

Concerning...Tornado Watch 359...

Valid 212042Z - 212215Z

The severe weather threat for Tornado Watch 359 continues.

SUMMARY...Occasional low-topped supercell development with risk for
short-lived tornadoes will continue across north central Gulf
coastal areas into early evening.

DISCUSSION...The recent increase in vigorous cellular convective
development with embedded mesocyclones, near coastal
Mississippi/Alabama and the western Florida panhandle, appears to be
accompanying the approach of a low-level speed maximum (50+ kt at
850 mb). This has contributed to the enlargement of low-level
hodographs in the presence of peak boundary layer instability
near/inland of the coast. This enhancement of activity may persist
another couple of hours, before the perturbation shifts inland of
coastal areas areas, where persistent convective cloud cover and
precipitation is maintaining more stable boundary layer conditions.

Meanwhile, 2 mb 2-hour surface pressure falls are now noted near
southern Louisiana coastal areas, just ahead of the center of Cindy.
As the cyclonic circulation continues to slowly approach this area,
strengthening low-level flow and shear may contribute to increasing
favorable conditions for low-topped supercells with risk for
tornadoes across portions of south central and southeast Louisiana
coastal areas by 00-02Z.

..Kerr.. 06/21/2017

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Mesoscale Discussion 1112
NWS Storm Prediction Center Norman OK
0629 PM CDT Wed Jun 21 2017

Areas affected...Southern Louisiana eastward to the Florida
Panhandle and southwestern Alabama

Concerning...Tornado Watch 359...

Valid 212329Z - 220030Z

The severe weather threat for Tornado Watch 359 continues.

SUMMARY...Tornado watch 359 continues until 00Z. A new tornado
watch is being considered at this time.

DISCUSSION...A strongly sheared, weakly unstable environment
continues to support some threat for a tornado or two - especially
across southern Alabama where several northward-moving storms have
exhibited at least modest low-level rotation. Farther west,
convection has decreased in coverage in response to drier air aloft
migrating into the region from the south. It is currently unclear
whether storms can re-develop across the region. Higher-resolution
guidance suggests that storms may redevelop across south-central
Louisiana that may pose a tornado threat later tonight, although
this regime is currently uncertain.

Latest thinking is that a replacement tornado watch will be needed
in southern Alabama and the adjacent Florida Panhandle as convective
cells with rotation continue to move northward across the region.
This watch will be issued within the hour. Farther west, trends
will be monitored for possible redevelopment of convection closer to
the center of Cindy, which may possibly necessitate a watch for
portions of southern Louisiana later tonight.

..Cook/Hart.. 06/21/2017

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Mesoscale Discussion 1113
NWS Storm Prediction Center Norman OK
0634 PM CDT Wed Jun 21 2017

Areas affected...south central Nebraska/western Kansas and vicinity

Concerning...Severe Thunderstorm Watch 360...

Valid 212334Z - 220130Z

The severe weather threat for Severe Thunderstorm Watch 360
continues.

SUMMARY...Scattered to isolated thunderstorms continue across parts
of the watch area, where local risk for hail and damaging wind gusts
continues.

DISCUSSION...Latest radar loop shows isolated thunderstorms ongoing
across south central Nebraska, and then more numerous storms
concentrated over southwest Kansas and vicinity. The storms are
ongoing near/ahead of a north-south surface trough, within an axis
of moderate instability (mixed-layer CAPE average 2000 to 3000 J/kg
per objective analysis). While flow aloft -- and thus deep-layer
shear -- remains on the marginal side for well-organized updrafts
(and hence the rather transient nature of the stronger cores),
potential for locally damaging winds and hail will continue over the
next couple of hours with a few of the strongest storms.

..Goss.. 06/21/2017

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Mesoscale Discussion 1114
NWS Storm Prediction Center Norman OK
0725 PM CDT Wed Jun 21 2017

Areas affected...southeast North Dakota...western Minnesota...and
northeast South Dakota

Concerning...Severe Thunderstorm Watch 361...

Valid 220025Z - 220230Z

The severe weather threat for Severe Thunderstorm Watch 361
continues.

SUMMARY...Scattered strong/locally severe thunderstorms continue
across WW 361, where severe risk continues.

DISCUSSION...Latest radar loop shows thunderstorms moving generally
eastward across areas in/near WW 361, with a few severe/supercell
storms evident based on radar characteristics. Storms across
northwest Minnesota continue to gradually weaken, consistent with
the fact that the axis of greatest instability remains within a
north-south axis near the North Dakota/Minnesota border. As storms
continue to encounter more stable air into north central Minnesota,
expect the weakening trend to continue.

Farther south, a supercell storm roughly 30 miles northwest of
Chandler, MN (AXN) is moving east-southeast, roughly along the
northern edge of a northwest-to-southeast instability gradient
paralleling a surface warm front extending from southeast Minnesota
across Iowa. While this storm will likely shift gradually
east-southeastward out of the watch, and continue to pose a severe
risk including potential for an isolated tornado, threat is not
expected at this time to become areally substantial enough
east/southeast of WW 361 to warrant new WW issuance.

Finally, storms remain weaker across northeast South Dakota, farther
from the influence of the upper system crossing southern portions of
the Canadian Prairie at this time. Still, an isolated/briefly
severe storm may affect southwest portions of the WW over the next
1-2 hours.

..Goss.. 06/22/2017

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Mesoscale Discussion 1115
NWS Storm Prediction Center Norman OK
0831 PM CDT Wed Jun 21 2017

Areas affected...central Nebraska south-southwest to the Oklahoma
Panhandle

Concerning...Severe Thunderstorm Watch 360...

Valid 220131Z - 220300Z

The severe weather threat for Severe Thunderstorm Watch 360
continues.

SUMMARY...Local severe risk continues across WW 360.

DISCUSSION...Latest radar loop shows a couple of strong/severe
storms continuing across central/south-central Nebraska at this
time, near the axis of maximum instability just ahead of the surface
trough. While storms may linger for a few more hours, severe risk
should gradually diminish.

Farther south, storms across southwest Kansas have evolved into a
small linear MCS, with some hints of stronger surging/bowing
segments within the line. Given a deep/dry boundary layer, locally
damaging winds will be possible with these storms in the next couple
of hours, though here too -- the overall trend will be for storms to
diminish as they shift southeast into a more stable airmass.

With the watch scheduled to remain in effect until 22/03Z, new ww
issuance is not expected.

..Goss.. 06/22/2017

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Mesoscale Discussion 1116
NWS Storm Prediction Center Norman OK
0907 PM CDT Wed Jun 21 2017

Areas affected...the northwest Minnesota vicinity

Concerning...Severe Thunderstorm Watch 361...

Valid 220207Z - 220300Z

The severe weather threat for Severe Thunderstorm Watch 361
continues.

SUMMARY...Severe risk continues to gradually diminish across the
remainder of WW 361.

DISCUSSION...Latest radar loop shows storms moving east across the
northern and western Minnesota vicinity, with an overall decrease in
intensity noted over the past 1-2 hours. With this trend expected
to continue, additional WW issuance across the region will likely
not be needed.

..Goss.. 06/22/2017

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Mesoscale Discussion 1117
NWS Storm Prediction Center Norman OK
0956 PM CDT Wed Jun 21 2017

Areas affected...Southeastern Mississippi...Southern Alabama...and
the western Florida Panhandle

Concerning...Tornado Watch 362...

Valid 220256Z - 220500Z

The severe weather threat for Tornado Watch 362 continues.

SUMMARY...The tornado threat continues across WW 362.

DISCUSSION...Bands of showers and thunderstorms (some exhibiting
occasional strong rotation) continue to migrate northward across WW
362. In the near term, the highest tornado threat appears to be
concentrated within a band of convection from about 30 miles south
of Selma, Alabama southward to near Crestview, Florida. Another
newly developed band of convection is exhibiting signs of weak
rotation just north of Biloxi, Mississippi. Throughout the night,
the overall strong shear/low CAPE regime will persist, with a
continued potential for isolated tornadoes with scattered convection
moving in from the north-central Gulf of Mexico.

..Cook.. 06/22/2017

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Mesoscale Discussion 1118
NWS Storm Prediction Center Norman OK
0224 AM CDT Thu Jun 22 2017

Areas affected...Portions of the central Gulf Coast

Concerning...Tornado Watch 362...

Valid 220724Z - 220900Z

The severe weather threat for Tornado Watch 362 continues.

SUMMARY...The threat for a few brief tornadoes may persist through
the remainder of the overnight across much of the region. New watch
issuance will be coordinated prior to the 08Z expiration of Watch
362.

DISCUSSION...Several corridors of convective activity continue early
this morning from near the center of Tropical Storm Cindy eastward
to Alabama and the western Florida Panhandle. The easternmost
convection remains the most likely to pose a tornado threat in the
near-term, as a broad 40-45kt low-level jet maintains adequate
effective helicity for occasional mesocyclogenesis. Unlike the
previous night, a broader region of weak buoyancy exists across the
region, as the warm front advanced inland and became more diffuse
with prior diurnal heating. In turn, while the tornado threat is not
quite as focused, convection stretching from southern Alabama
southward to the Gulf may still pose a threat for a few brief
tornadoes.

Farther west, drier mid-level air has kept convection shallower,
with little/no CG lightning noted recently. However, some westward
evolution of the low-level jet maximum may further promote renewed
activity towards daybreak from southeast Louisiana northward into
Mississippi. Adequate speed shear in the 0-1km layer and rich
moisture could yield a threat of brief tornadoes here as well.
Therefore, with Watch 362 expiring at 08Z, a new watch will be
coordinated shortly.

..Picca.. 06/22/2017

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Mesoscale Discussion 1119
NWS Storm Prediction Center Norman OK
0311 AM CDT Thu Jun 22 2017

Areas affected...Portions of the northern Plains

Concerning...Severe potential...Watch unlikely

Valid 220811Z - 220915Z

Probability of Watch Issuance...20 percent

SUMMARY...A few intensifying thunderstorms early this morning may be
capable of isolated instances of large hail, and perhaps a few
stronger gusts. However, the threat is currently expected to remain
limited enough to preclude watch issuance.

DISCUSSION...On the southern fringe of a mid/upper jet maximum,
isolated/widely scattered thunderstorms have developed early this
morning. Recent Aberdeen, SD (KABR) VWP data exhibit westerly
mid-level flow around 50-60kt, with resultant deep-layer shear
sufficient for updraft organization/rotation. Therefore, as these
cells move east into more substantial mid-level buoyancy (e.g.,
MUCAPE around 1000-2000 J/kg), they may be capable of isolated large
hail reports. Moreover, despite being rooted above the surface
(likely near 700mb), pockets of sufficient low-level temp/dew point
spreads may support occasional strong, gusty surface winds. This
threat will be further enhanced by small bowing segments resulting
from somewhat uni-directional flow in the convective layer.
Nonetheless, any severe threat is currently expected to remain
spatially limited, likely precluding overnight watch issuance.

..Picca/Edwards.. 06/22/2017

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Mesoscale Discussion 1120
NWS Storm Prediction Center Norman OK
0928 AM CDT Thu Jun 22 2017

Areas affected...Northern IA...Southern MN

Concerning...Severe potential...Watch unlikely

Valid 221428Z - 221600Z

Probability of Watch Issuance...20 percent

SUMMARY...A small convective system will pose a threat of isolated
damaging wind and hail through the morning. At this time, watch
issuance is considered unlikely.

DISCUSSION...A small convective system has recently evolved over
southern MN and far northern IA. This system is being supported by
moderate MUCAPE (1250-2000 J/kg per recent mesoanalyses) and
sufficient effective shear to support some convective organization.
This convection is expected to persist through the morning as it
moves along and just north of a weak surface boundary over northern
IA, with some reorganization possible as convection redevelops
immediately downstream.

Rather strong pressure rises noted immediately upstream indicate
that the system has become somewhat organized. However, the severity
of the system may tend to remain somewhat limited. While instability
is sufficient for hail, a primarily linear or cluster convective
mode will not be favorable. Meanwhile, the elevated nature of the
convection and lack of substantial heating downstream (due to
ongoing elevated convection over northeast IA) will likely temper
the severe wind threat to some extent. For these reasons, watch
issuance is considered unlikely, though a few instances of damaging
wind and/or marginally severe hail will be possible through the
morning as the system moves eastward.

..Dean/Guyer.. 06/22/2017

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Mesoscale Discussion 1121
NWS Storm Prediction Center Norman OK
1150 AM CDT Thu Jun 22 2017

Areas affected...Central/eastern LA...Central/southern
MS...Southeast AR...Central/southern AL...FL Panhandle

Concerning...Tornado Watch 363...

Valid 221650Z - 221815Z

The severe weather threat for Tornado Watch 363 continues.

SUMMARY...Isolated tornado threat continues east of Tropical
Depression Cindy. New watch issuance is likely before 18Z.

DISCUSSION...Thus far this morning, the strongest convection (and
occasional rotation) has been noted across the eastern portion of WW
363, with a possible waterspout/tornado reported earlier this
morning near Pensacola. This region is located within the strong
belt of deep, moist southerly flow to the east of a well-defined
midlevel dry slot that is wrapping into TD Cindy. While wind
profiles are southerly through a deep layer, backing of the
low-level flow is supporting substantial low-level shear, with 0-1
km shear of 25-35 kts noted per recent mesoanalyses and VWP data.
Very warm midlevel temperatures and poor lapse rates will continue
to limit the intensity of convection through the day, but the the
strongest cells will pose an isolated tornado threat given the
aforementioned low-level shear magnitude coincident with a very
moist, tropical airmass and potential for some additional
destabilization as modest heating continues. Some threat may spread
north out of the watch by early afternoon, though it is unclear at
this time whether any northward expansion of the watch will be
necessary.

Further east, closer to the primary circulation of TD Cindy,
convection has likely been inhibited by very dry midlevel air noted
on WV imagery. However, greater insolation within the dry slot has
allowed stronger heating to occur, and convection has begun to
gradually increase across southern/eastern LA and southern MS.
Continued destabilization within a low-level environment that is
very moist and strongly sheared will support a gradual increase in
the tornado threat through the day across portions of LA into
western MS.

Since some tornado threat is likely to persist through the afternoon
across WW 363, a new tornado watch will likely be required before
18Z covering generally the same area from LA eastward through MS,
and perhaps northward into southeast AR and eastward into portions
of AL and the FL Panhandle.

..Dean/Guyer.. 06/22/2017

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Mesoscale Discussion 1122
NWS Storm Prediction Center Norman OK
1218 PM CDT Thu Jun 22 2017

Areas affected...Portions of northeastern OH...western/central
PA...and western NY

Concerning...Severe potential...Watch unlikely

Valid 221718Z - 221945Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated threat for strong to locally damaging winds
and marginally severe hail may persist through the afternoon.
Overall threat should remain too marginal for watch issuance.

DISCUSSION...17Z objective analysis of surface observations
indicates a warm front is draped from southeastern lower MI across
Lake Erie into western NY and northern PA. The airmass along/south
of the front has become weakly unstable early this afternoon, with
MLCAPE generally ranging 500-1000 J/kg per 17Z RAP Mesoanalysis.
Further diurnal heating may allow for MLCAPE values to approach 1500
J/kg across parts of western/central PA through 20Z. In association
with a weak mid-level disturbance embedded within strong westerly
flow at mid/upper levels, isolated thunderstorms have developed
across eastern Lake Erie into parts of far western NY and
northwestern PA. One of these cells exhibited brief supercell
characteristics before weakening across Butler into Armstrong County
PA.

Most of western NY into into western/central PA and northeastern OH
will remain displaced to the south of stronger mid-level flow across
the upper Great Lakes into southern Ontario/Quebec and New England.
Still, around 30-35 kt of westerly flow at 500 mb will support
similar values of effective bulk shear through the afternoon across
this region. Additional convective development across northeastern
OH along the shore of Lake Erie will be possible over the next
several hours, and any thunderstorms that can remain along/south of
the front will have the potential to be surface-based. Given the
marginal shear values, multicells will probably be the dominant
storm mode, posing a strong to locally damaging wind and perhaps
marginally severe hail threat. The lack of even stronger instability
(mainly owing to weak mid-level lapse rates) and shear will likely
preclude a more robust severe weather threat through the remainder
of the afternoon. Accordingly, watch issuance is unlikely at this
time.

..Gleason/Guyer.. 06/22/2017

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Mesoscale Discussion 1123
NWS Storm Prediction Center Norman OK
0112 PM CDT Thu Jun 22 2017

Areas affected...Portions of eastern CO

Concerning...Severe potential...Watch possible

Valid 221812Z - 222015Z

Probability of Watch Issuance...40 percent

SUMMARY...Some increase in the threat for large hail and strong to
damaging winds should occur with thunderstorms developing this
afternoon. Watch issuance is possible.

DISCUSSION...Recent visible satellite imagery shows towering cumulus
building along the Front Range of eastern CO near Boulder as a
surface cold front provides the low-level convergence needed to
support convective initiation. Even though low-level moisture
remains quite limited at the moment along/north of the front,
continued diurnal heating and a gradual increase in low-level
moisture (even with northerly trajectories) is expected through the
remainder of the afternoon across much of eastern CO per surface
observations. Steep mid-level lapse rates are also present across
much of this region per 12Z sounding from DNR. As this gradual
increase in low-level moisture occurs, a corresponding increase in
instability is expected, with MLCAPE of generally 500-1500 J/kg
expected by peak heating around 22-00Z. Although low-level flow
should remain weak, mid-level winds around 20-40 kt and a strongly
veering profile with height should support about 35-45 kt of
effective bulk shear, stronger across northeastern CO. A mix of
supercells and short line segments may develop both along the Front
Range and the surface cold front. Isolated large hail and strong to
locally damaging winds appear possible with these thunderstorms, and
a watch may be needed in the next several hours across parts of
eastern CO depending on short-term radar and observational trends.

..Gleason/Guyer.. 06/22/2017

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Mesoscale Discussion 1124
NWS Storm Prediction Center Norman OK
0308 PM CDT Thu Jun 22 2017

Areas affected...North Georgia

Concerning...Severe potential...Watch unlikely

Valid 222008Z - 222145Z

Probability of Watch Issuance...20 percent

SUMMARY...Mini-supercells with a threat of a brief tornado or two
will continue this afternoon. Limited coverage and magnitude of the
threat makes watch issuance unlikely.

DISCUSSION...Mini-supercell development has recently taken place
across north Georgia, just to the northwest of Atlanta. While
low-level flow is not quite as strong as areas further west, a very
moist boundary layer, modest instability, and favorably veering
low-level wind profiles will continue to support the development of
small rotating cells through the afternoon. The greatest threat will
likely be near and just north of a diffuse surface boundary across
north Georgia, where surface winds are backed to more of an
east-southeasterly direction. A tornado or two will be possible as
these small cells interact with the surface boundary.

..Dean/Guyer.. 06/22/2017

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Mesoscale Discussion 1125
NWS Storm Prediction Center Norman OK
0348 PM CDT Thu Jun 22 2017

Areas affected...Eastern LA...Southeast AR...MS...AL...Western GA

Concerning...Tornado Watch 364...

Valid 222048Z - 222215Z

The severe weather threat for Tornado Watch 364 continues.

SUMMARY...The threat for a tornado or two and locally damaging wind
gusts continues in and near WW 364. Short-term trends will be
monitored closely with regard to the need for additional watches to
the north or east.

DISCUSSION...The most active convection across WW 364 continues to
cover the western and eastern third of the watch area, with a local
minimum over much of MS into western AL. To the west across
northeast LA/southeast AR into western MS, multiple arcing bands of
convection have developed. This more linear configuration will
support a threat of locally damaging winds, especially given
relatively strong heating and some potential for transport of strong
southerly momentum to the surface, while the linear mode is somewhat
less favorable for a tornado threat. These convective bands will
eventually move into portions of northern MS not currently in WW
364. Short-term trends will be monitored for the need of a new watch
to cover this threat.

On the eastern side of the watch, the strongest convection has
shifted to eastern AL, with strong convection also developing over
western GA. Convection remains somewhat more cellular in nature
across this area, and the threat of a tornado or two remains,
especially near any precipitation-enhanced surface boundaries. The
threat near a more well-defined surface boundary across north GA was
discussed in previous MCD 1124. Short-term trends will be closely
monitored across portions of west and north GA with regard to the
need for watch issuance.

A local minimum in convection persists across the central portion of
WW 364 across much of MS into western AL. Despite strong heating in
this area, weak low-level convergence and entrainment of dry air
aloft has likely limited convective intensity thus far. It is
unclear whether robust redevelopment will occur in this area, but a
conditional risk for a brief tornado or two and isolated damaging
wind will exist with any deep convection that can persist later this
afternoon.

..Dean/Guyer.. 06/22/2017

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Mesoscale Discussion 1126
NWS Storm Prediction Center Norman OK
0354 PM CDT Thu Jun 22 2017

Areas affected...Portions of western/central KS into south-central
NE

Concerning...Severe potential...Watch possible

Valid 222054Z - 222330Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated instances of large hail and damaging winds may
occur with thunderstorms forming along a cold front over the next
several hours. Watch issuance is possible.

DISCUSSION...Strong daytime heating has encouraged surface
temperatures to warm into the mid to upper 90s across
western/central KS into south-central NE as of 2045Z. A weak cold
front draped from northeast to southwest across this region will
provide a focus for low-level convergence and possible convective
development over the next few hours. 20Z RAP Mesoanalysis shows CIN
eroding from west to east along the front, and recent visible
satellite imagery shows several attempts at initiation across
southwestern KS. Steep mid-level lapse rates emanating from the
higher terrain of western/central CO have overspread this region,
and combined with surface dewpoints in the low to mid 60s are
contributing to generally 1000-1500 J/kg of MLCAPE.

The strongest mid-level winds will likely remain a bit to the north
of western/central KS and south-central NE, but a veering wind
profile with height should support 35-40 kt of effective bulk shear
through the early evening. It is not entirely clear how much
convection will form along the front late this afternoon, but any
thunderstorm that does form will pose an isolated threat for large
hail and strong/damaging winds. In addition, ongoing convection
across eastern CO may also contain an isolated severe risk as it
moves into western KS over the next several hours. Radar and
observational trends will be monitored for possible watch issuance
through 23Z.

..Gleason/Guyer.. 06/22/2017
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 24, 2017 7:40 pm

Nada importante para el día de hoy. Solamente algunas zonas con riesgo marginal.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0251 PM CDT Sat Jun 24 2017

Valid 242000Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE
SOUTHERN ROCKIES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHEAST...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER MIDWEST...

...SUMMARY...
Isolated strong to severe thunderstorms with damaging winds will be
possible over portions of the Southeast and possibly the Upper
Midwest this afternoon. Other storms capable of isolated severe hail
and strong winds are expected over parts of New Mexico.

...Mid-afternoon Update...

No appreciable changes to 1630z update.

Strong boundary-layer heating across western NM has contributed to
significant buoyancy across portions of the southern Rockies.
Convection is beginning to mature along the western fringe of higher
quality moisture where deep-layer shear is more than adequate for
sustaining updrafts. This region should remain convectively active
into the evening hours.

Scattered thunderstorms have developed along a pre-frontal zone of
low-level confluence from central GA into coastal NC. Gusty winds
may be noted with this activity until buoyancy is overturned later
this afternoon.

..Darrow.. 06/24/2017

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Jun 24 2017/

...Carolinas/Southeast States...
Ahead of a southeastward-moving cold front, a moist warm sector with
low 70s F dewpoints resides across the region. The atmosphere will
become moderately unstable especially over the Carolinas with 1500
J/kg MLCAPE as the boundary layer warms. Storms are expected to
redevelop along the front and over the higher terrain and intensify
as they intercept the moist and unstable warm sector. On the
southern fringe of moderate winds aloft, 30-35 kt effective shear
will support multicells and weak mid-level updraft rotation. These
storms may produce a few instances of strong to damaging wind gusts
as they develop eastward through the Carolinas this afternoon into
early evening.

...New Mexico/far southern Colorado...
Widespread low clouds may largely persist across eastern
NM/southeast CO today. However, diabatic warming over the higher
terrain with steep lapse rates will likely foster modest MLCAPE and
the development of storms during the afternoon especially across
interior NM. Wind profiles are sufficient for some mid-level updraft
rotation with storms developing over northern NM and possibly far
southern CO. Otherwise, multicells with isolated downburst winds and
hail are expected from later this afternoon into early evening.

...Upper Midwest...
While boundary-layer moisture will be quite meager ahead of a
southeastward-moving cold front, low-level moisture (40s F surface
dewpoints) may be sufficient for some low-topped thunderstorms near
the front. Steep lapse rates and relatively strong low/mid-level
westerly winds may be sufficient for some convectively enhanced wind
gusts this afternoon through around sunset.

...South-central Texas...
Thunderstorms will persist/redevelop today largely along
consolidated outflow and zones of differential heating under the
influence of weak forcing and weak winds aloft. While a few
pulse-type storms capable of strong downdraft winds may occur this
afternoon/early evening with a moist/unstable environment, the
overall severe potential is expected to remain limited.

A las 01:00z, se actualiza de vuelta.
---------------------------------------------------------------
Últimas discusiones a mesoescala.
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Mesoscale Discussion 1127
NWS Storm Prediction Center Norman OK
0659 PM CDT Thu Jun 22 2017

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

Concerning...Severe potential...Watch possible

Valid 222359Z - 230100Z

Probability of Watch Issuance...40 percent

SUMMARY...Risk for isolated/brief tornadoes is evident in the
northeast quadrant of the circulation surrounding T.D. Cindy.
Isolated nature of the risk thus far does not seem to warrant WW
issuance. We will continue to monitor environmental and convective
trends across the area.

DISCUSSION...Latest radar loop shows convection -- including an
arcing band of storms from central Arkansas into southwest Tennessee
and northern Mississippi -- ongoing in the northeast quadrant of
T.D. Cindy and shifting northward with time in conjunction with
Cindy's advance.
Latest surface analysis and WSR-88D VWP data reveals rather
pronounced backing in the low-level flow field within this area,
with resulting 0-1 km shear supporting low-level rotation with a few
convective cells.

With low-level flow surrounding Cindy progged to remain relatively
strong, expect limited tornado risk to persist into the overnight
hours. However, areal coverage of the risk remains sufficiently
limited such that the need for a new tornado watch north of WW 364
remains questionable at this point, and may ultimately not be
required. However, any increase in coverage and/or intensity of
convection northeast of the center of circulation would require more
serious consideration for WW issuance.

..Goss/Hart.. 06/22/2017

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Mesoscale Discussion 1128
NWS Storm Prediction Center Norman OK
0857 PM CDT Thu Jun 22 2017

Areas affected...the central Gulf Coast region

Concerning...Tornado Watch 364...

Valid 230157Z - 230300Z

The severe weather threat for Tornado Watch 364 continues.

SUMMARY...As T.D. Cindy continues moving northward, tornado risk
continues to very gradually decrease across the WW area. While an
isolated/brief tornado or two will remain possible into the
overnight hours, new watch issuance is not expected beyond the
scheduled 03Z expiration of WW 364.

DISCUSSION...Latest surface and radar data show the center of T.D.
Cindy -- now over southwest Arkansas -- continues moving slowly
north-northeast. While a broad zone of isolated to scattered
showers and thunderstorms continue from east Texas eastward across
the southeast U.S., the most favorable shear with respect to
low-level rotation/tornado risk -- i.e. within the northeast
quadrant of Cindy -- continues shifting northward across the lower
Mississippi Valley region. Meanwhile, weaker low-level shear
continues to spread northward across the central Gulf Coast area,
contributing to a gradual decrease in tornado risk. With this trend
to continue as Cindy progresses farther inland, a new watch -- to
replace WW 364 subsequent to its scheduled 23/03z expiration -- is
not anticipated.

..Goss.. 06/23/2017

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Mesoscale Discussion 1129
NWS Storm Prediction Center Norman OK
0909 PM CDT Thu Jun 22 2017

Areas affected...Central/Northeast IA

Concerning...Severe potential...Watch unlikely

Valid 230209Z - 230415Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated hail and damaging wind gusts are possible with
thunderstorms along the front as it moves across IA. A generally
limited severe threat is anticipated and a watch is not anticipated,
but convective trends will be monitored closely.

DISCUSSION...Thunderstorms have developed over the past hour along
the cold front extending from CCY (in northeast IA) southwestward to
CBF (in southwest IA). Airmass ahead of this cold front is
characterized by dewpoints in the low 70s, which, when combined with
steep mid-level lapse rates (i.e. around 7-7.5 deg C per km per the
latest mesoanalysis), is supportive of moderate instability.
Continued southeastward progress of the cold front into this airmass
is expected to result in continued thunderstorm development along
the cold front. This region is along the southern periphery of the
stronger flow aloft but enough shear (i.e. effective shear around 30
kt) exists to support some updraft organization and a supercell or
two, particularly across northern portions of the region where the
shear is strongest. Hail is possible with these more organized
storms. Farther south, a more multicellular mode is anticipated with
any hail likely a result of brief updraft intensification due to
cell mergers. Some upscale growth into a more linear system is
possible but the generally modest mid-level flow (and shear) are
expected to preclude anything but occasionally damaging winds. As a
result, a watch is not current expected but trends will be monitored
for upscale growth and a resulting increase in the damaging wind
threat.

..Mosier/Hart.. 06/23/2017

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Mesoscale Discussion 1130
NWS Storm Prediction Center Norman OK
1054 AM CDT Fri Jun 23 2017

Areas affected...Middle TN...Northeast MS...Central/northern AL

Concerning...Severe potential...Watch likely

Valid 231554Z - 231730Z

Probability of Watch Issuance...80 percent

SUMMARY...A gradual increase in the severe threat is expected late
this morning into the afternoon. A few tornadoes and isolated
damaging wind gusts will be the primary threats. Watch issuance is
likely late this morning or early this afternoon.

DISCUSSION...Convection has been increasing in intensity this
morning, along the leading edge of the broader precipitation shield
associated with TC Cindy. The environment ahead this convection is
characterized by very moist/tropical profiles, with poor lapse rates
but favorable wind profiles for supercells and other organized storm
structures. As continued heating and modest destabilization occurs
downstream, the severe threat is expected to increase. Recent CAM
guidance is suggestive of a mixed-mode threat, with some tornado
threat resulting from mini-supercell development, while a threat of
damaging wind gusts will increase with larger-scale convective line
segments.

In a relative sense, the tornado threat will likely be greatest
across the northern portion of the MCD area, where backed low-level
flow will increase low-level shear/SRH, while the wind threat may be
maximized further south, where low-level flow remains strong but
vertical profiles would tend to favor line segments. One or more
watches are likely late this morning or early this afternoon to
cover these threats.

..Dean/Guyer.. 06/23/2017

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Mesoscale Discussion 1131
NWS Storm Prediction Center Norman OK
1215 PM CDT Fri Jun 23 2017

Areas affected...Northern KY...Southern/eastern OH...Western
WV...Western PA

Concerning...Severe potential...Watch possible

Valid 231715Z - 231915Z

Probability of Watch Issuance...40 percent

SUMMARY...A gradual increase in the threat for damaging wind gusts
and perhaps a tornado or two is expected this afternoon. Watch
issuance is possible.

DISCUSSION...A gradual increase in the intensity and coverage of
convection has been noted across portions of southern OH, in advance
of a large precipitation shield (with embedded convection) further
to the northwest. While midlevel lapse rates are poor, given the
influence of the decaying tropical system to the southwest, modest
heating within a very moist environment has resulted in moderate
destabilization, with SBCAPE rising into the 1000-1500 J/kg range
where temperatures have warmed into the low 80s F. Further
intensification is possible, both with the more discrete activity
across southern OH and northern KY, and within the larger convective
plume across central/northern OH as that moves eastward.

With strong deep-layer southwesterly flow over the region, effective
shear has increased into the 40-50 kt range, which is more than
sufficient for some organized storm structures. With unidirectional
wind profiles in place, damaging wind gusts are expected to the
primary threat, though low-level shear is sufficient for a tornado
or two with any semi-discrete supercells that can evolve. Watch
issuance is possible later this afternoon to cover this threat.

..Dean/Guyer.. 06/23/2017

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Mesoscale Discussion 1132
NWS Storm Prediction Center Norman OK
1222 PM CDT Fri Jun 23 2017

Areas affected...Portions of far southern MO...eastern OK...and AR

Concerning...Severe potential...Watch possible

Valid 231722Z - 231945Z

Probability of Watch Issuance...40 percent

SUMMARY...Convection across southeastern MO may gradually organize
into a line of storms across northern AR/eastern OK over the next
several hours. Strong to locally damaging winds should be the main
threat with this activity, and watch issuance is possible this
afternoon.

DISCUSSION...A cluster of thunderstorms is occurring along a cold
front across southwestern MO as of 17Z. In addition to the low-level
forcing of the front, at least the glancing influence of large-scale
ascent associated with a shortwave trough over western/central KS
will likely aid sustained convection across this region through the
afternoon and early evening. A very moist low-level airmass is
present across AR and far eastern MO based on the 12Z sounding from
LZK and latest surface observations indicating dewpoints remain in
the low to mid 70s. Surface temperatures have already warmed into
the 80s downstream of ongoing convection. Additional diurnal heating
and modestly steepened mid-level lapse rates (generally 6.5-7.5 C/km
in the 700-500 mb layer) overspreading eastern OK into AR should
further increase instability early this afternoon, with MLCAPE
values of 2000-3000 J/kg becoming common through peak heating.

Mid-level winds will likely remain somewhat modest, as stronger flow
aloft remains displaced to the north. But, around 25-30 kt of
northwesterly flow around 500 mb should support at least a
semi-organized line of thunderstorms moving southeastward across
eastern OK into AR this afternoon and early evening. Additional
storms may form along the cold front in eastern OK. Given the linear
mode expected, strong to damaging winds would likely be the main
threat, although marginally severe hail could also occur with the
strongest cores embedded within the line. The lack of even stronger
mid-level winds and related shear may temper the overall severe
threat somewhat, but recent convection-allowing model guidance is
generally consistent with the scenario described above. Watch
issuance will be possible this afternoon based on short-term
observational and radar trends.

..Gleason/Guyer.. 06/23/2017

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Mesoscale Discussion 1133
NWS Storm Prediction Center Norman OK
1239 PM CDT Fri Jun 23 2017

Areas affected...Central and eastern KY

Concerning...Severe potential...Watch possible

Valid 231739Z - 231945Z

Probability of Watch Issuance...40 percent

SUMMARY...Some increase in the threat for damaging wind gusts and a
tornado or two is expected this afternoon. Watch issuance is
possible.

DISCUSSION...Convection has thus far been slow to increase across
much of KY, but continued heating/destabilization, along with the
increasing influence of remnant TC Cindy, will result in an increase
in the threat for organized convection this afternoon. SBCAPE of
1000-1500 J/kg, combined with effective shear of 40-50 kts, will
result in the potential for organized storm structures, with both
small supercells and larger-scale line segments possible as
convection evolves with time. While weak midlevel lapse rates will
tend to limit updraft intensity, moderate-to-strong southwesterly
flow through a deep layer will support a threat of damaging winds.
Low-level shear is sufficient for a tornado or two, especially in
closer proximity to the surface circulation where low-level winds
are locally backed. Watch issuance is possible later this afternoon
to cover this threat.

..Dean/Guyer.. 06/23/2017

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Mesoscale Discussion 1134
NWS Storm Prediction Center Norman OK
0102 PM CDT Fri Jun 23 2017

Areas affected...Portions of NY...VT...NH...ME...and MA

Concerning...Severe potential...Watch unlikely

Valid 231802Z - 232030Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong to damaging winds and perhaps some hail
may occur with strong to severe thunderstorms through the early
evening. The overall severe weather threat will probably remain too
marginal to warrant watch issuance, although radar trends will
continue to be monitored.

DISCUSSION...Around 40-55 kt of mid-level southwesterly flow is
present this afternoon across much of New England and vicinity as
large-scale upper troughing approaches this region from the west.
Breaks in the cloud cover have allowed surface temperatures to
generally warm into the upper 70s to mid 80s away from the coast,
and a moist low-level airmass is present, with surface dewpoints in
the mid 60s to around 70. A warm front at the surface is located
from southern Quebec across NH and western ME as of 18Z, and this
front should make some northward progress into central/eastern ME
through the remainder of the afternoon. Although mid-level lapse
rates remain generally poor across this region per 12Z soundings
from GYX/ALB, 250-1000 J/kg of MLCAPE is present as of 18Z owing to
the previously mentioned diurnal heating and moist low-level
airmass.

A veering/strengthening wind profile with height will support 35-45
kt of effective bulk shear, which should encourage some updraft
organization. Steep low-level lapse rates and a well mixed boundary
layer will encourage efficient momentum transfer of stronger
thunderstorm downdraft winds to the surface, and locally damaging
surface winds appear to be the main threat with this activity. Some
hail may also occur, but poor mid-level lapse rates will likely
limit a more substantial severe hail threat. Present indications are
for the overall severe threat to remain isolated through peak
heating, which suggests watch issuance will probably not be needed.

..Gleason/Guyer.. 06/23/2017

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Mesoscale Discussion 1135
NWS Storm Prediction Center Norman OK
0235 PM CDT Fri Jun 23 2017

Areas affected...Portions of eastern PA...NJ...and far northern DE

Concerning...Severe potential...Watch possible

Valid 231935Z - 232130Z

Probability of Watch Issuance...40 percent

SUMMARY...An isolated damaging wind threat may develop from central
into eastern PA and NJ/DE late this afternoon. Watch issuance is
possible.

DISCUSSION...Scattered convection has formed this afternoon across
western/central PA along a differential heating boundary and surface
trough, moving eastward around 35-40 kt. Visible satellite imagery
shows at least partial clearing across eastern PA into NJ and far
northern DE downstream of ongoing thunderstorms. Even though
mid-level lapse rates will remain mostly poor across this region,
daytime heating and a very moist low-level airmass (surface
dewpoints in the upper 60s to lower 70s) are contributing to MLCAPE
of 500-1500 J/kg. Strong 40-50 kt mid-level winds and a
strengthening low-level jet through this evening are supporting
40-50 kt of effective bulk shear. Strong to locally damaging winds
will probably be the main threat with any line segments/marginal
supercells moving into this region from the west. In addition, with
low-level winds generally veered to southwesterly and only modest
additional veering with height, effective SRH will probably remain
limited, but may be sufficient to support some updraft rotation and
perhaps a tornado or two. Although not immediately likely, a watch
may need to be considered in the next several hours pending latest
radar trends.

..Gleason/Guyer.. 06/23/2017

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Mesoscale Discussion 1136
NWS Storm Prediction Center Norman OK
0315 PM CDT Fri Jun 23 2017

Areas affected...Portions of central/southern NM into west TX

Concerning...Severe potential...Watch unlikely

Valid 232015Z - 232245Z

Probability of Watch Issuance...5 percent

SUMMARY...A marginal wind/hail threat should persist through this
evening. Due to the very isolated severe risk, watch issuance is not
expected at this time.

DISCUSSION...Isolated thunderstorms have formed along a shallow cold
front across southeastern NM into west TX this afternoon. Additional
isolated convection may develop along the central mountain chain in
NM within a forced upslope/easterly low-level flow regime. Modest
northwesterly flow around 500 mb of 20-25 kt will likely act to
limit updraft organization and overall storm motions. But, a
strongly veering wind profile with height in the vicinity of the
cold front per recent LBB VWP is supporting generally 30-40 kt of
effective bulk shear. With steep mid-level lapse rates and MLCAPE of
500-1500 J/kg present across this region, the strongest
thunderstorms may pose a very isolated large hail risk, in addition
to some threat for strong to locally damaging downdraft winds. Due
to overall thunderstorm coverage expected to remain generally
isolated, and marginal low/mid-level winds forecast to remain over
this region through this evening, watch issuance is not anticipated.

..Gleason/Guyer.. 06/23/2017

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Mesoscale Discussion 1137
NWS Storm Prediction Center Norman OK
0317 PM CDT Fri Jun 23 2017

Areas affected...Middle and eastern TN...Northern/central
AL...Northwest GA...Far eastern MS

Concerning...Tornado Watch 365...

Valid 232017Z - 232215Z

The severe weather threat for Tornado Watch 365 continues.

SUMMARY...Threat for damaging wind gusts and a tornado or two
continues in and near WW 365.

DISCUSSION...A broken line of convection has evolved across middle
TN into central/northern AL and far eastern MS. Periodic bowing
segments have developed along this line during the last 1-2 hours,
and these may continue to develop through the late afternoon, given
moderately strong, unidirectional southwesterly wind profiles. Ahead
of the line, somewhat more discrete convection has developed ahead
of the main line. Low-level shear remains sufficient for a tornado
or two, particularly with the strongest of the more discrete cells
ahead of the line, while sporadic damaging wind gusts will continue
to be possible, especially with any bowing segments that persist.

Some severe threat will continue immediately south and east of the
watch, though wind profiles become increasingly marginal with
eastern/southern extent. At this point, it is uncertain whether any
watch expansion or new watch issuance will be required to cover any
threat outside of WW 365.

..Dean.. 06/23/2017

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Mesoscale Discussion 1138
NWS Storm Prediction Center Norman OK
0332 PM CDT Fri Jun 23 2017

Areas affected...Portions of southern/eastern OK...north TX...and
far west-central AR

Concerning...Severe potential...Watch possible

Valid 232032Z - 232230Z

Probability of Watch Issuance...40 percent

SUMMARY...An isolated damaging wind and perhaps large hail threat
may increase with thunderstorms developing along a cold front this
afternoon. Watch issuance is possible.

DISCUSSION...Isolated thunderstorms developing along a
southward-moving cold front should increase in coverage over the
next several hours as they encounter an increasingly moist and
unstable airmass. Surface temperatures to the south of the front
have mostly warmed into the low to mid 90s, and plentiful low-level
moisture combined with at least modestly steep mid-level lapse rates
have resulted in strong MLCAPE ranging from 2500-3500 J/kg. The main
uncertainty regarding the overall severe threat across this region
remains weak low and mid-level winds. Related effective bulk shear
values of 20 kt or less will likely preclude a more organized
damaging wind threat. However, at least isolated instances of
marginally severe hail and strong/damaging winds will remain
possible through this evening with pulse-severe-like convection
along the front. At this time, the prospect for watch issuance
remains unclear, and will largely depend on short-term
radar/observational trends.

..Gleason/Guyer.. 06/23/2017

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Mesoscale Discussion 1139
NWS Storm Prediction Center Norman OK
0353 PM CDT Fri Jun 23 2017

Areas affected...Northern KY...Southern OH...Northern WV...Western
MD...Southern PA

Concerning...Severe Thunderstorm Watch 366...

Valid 232053Z - 232300Z

The severe weather threat for Severe Thunderstorm Watch 366
continues.

SUMMARY...The threat for damaging winds and perhaps a brief tornado
continues.

DISCUSSION...Several clusters of thunderstorms are ongoing across
the valid portion of WW 366, with a tendency for convection to
evolve into short line segments. This mode is generally expected to
continue, given unidirectional southwesterly wind profiles across
the region. Periodic damaging wind gusts will be possible with these
line segments, while a brief tornado also cannot be ruled out, given
relatively strong 0-1 km shear of 20-30 kts noted in VWPs from CCX
and PBZ. A somewhat greater conditional threat of a tornado or two
would exist with any discrete cells that can be maintained, though
thus far convection has rather quickly evolved into line segments as
storms intensify.

A cluster of storms moving into southeast PA will begin to move out
of WW 366 within the hour, posing some severe threat into at least
southeast PA. Please refer to MCD 1135 for additional details
regarding the severe threat downstream of WW 366.

..Dean.. 06/23/2017

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Mesoscale Discussion 1140
NWS Storm Prediction Center Norman OK
0435 PM CDT Fri Jun 23 2017

Areas affected...Portions of northern/central AR...far southeastern
MO...far western TN...and far northwestern MS

Concerning...Severe Thunderstorm Watch 367...

Valid 232135Z - 232300Z

The severe weather threat for Severe Thunderstorm Watch 367
continues.

SUMMARY...An isolated strong/gusty wind threat with associated risk
for tree damage continues with a line of thunderstorms moving
southeastward across WW 367.

DISCUSSION...Outflow has recently surged ahead of an ongoing line of
thunderstorms across parts of northern/central AR per KLZK radar
imagery. The eastern extent of the line (across northeastern AR)
remains more orthogonal to modest northwesterly mid-level flow, and
may pose a locally greater damaging wind risk over the next several
hours as it approaches the AR/TN state line. The forecast office in
Memphis TN has recently expanded the watch eastward slightly into
far western TN/northwestern MS to account for this threat. An
isolated strong/gusty wind risk should also continue farther west
into central AR, where sporadic instances of trees down have been
reported this afternoon. The airmass downstream of ongoing
convection remains moderately to strongly unstable per 21Z RAP
Mesoanalysis, and should support the continuation of the line
through the early evening hours. Later this evening, the loss of
daytime heating with resultant lessening of instability and
continued modest mid-level winds should result in gradual weakening
of the line.

..Gleason.. 06/23/2017

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Mesoscale Discussion 1141
NWS Storm Prediction Center Norman OK
0450 PM CDT Fri Jun 23 2017

Areas affected...Kentucky...Far Western Virginia...Southwestern West
Virginia...Far Southern Ohio

Concerning...Tornado Watch 368...

Valid 232150Z - 232345Z

The severe weather threat for Tornado Watch 368 continues.

SUMMARY...An isolated tornado threat should continue for a few more
hours across parts of central and eastern Kentucky. The threat is
expected to remain mostly confined to the area covered by WW 368 and
no additional weather watch issuance is expected.

DISCUSSION...The remnants of Cindy are currently moving into the
Ohio Valley with the center of circulation located in the
southwestern part of WW 368 across southern Kentucky. Ahead of the
circulation, instability is weak but the airmass is very moist with
surface dewpoints in the lower 70s F and precipitable water values
in the 2.00 to 2.25 range according to the RAP. In addition, the
WSR-88D VWPs at Charleston, WV and Tri-Cities, TN show 0-6 km shear
near 40 kt with 0-3 km storm relative helicity around 250 m2/s2. The
low-level shear over south-central Kentucky appears to be even
stronger associated with a low-level speed max at 850 mb. The
low-level shear will continue to support a tornado threat across
central and eastern Kentucky into early evening. The greatest
tornado threat would be associated with the smaller more discrete
cells that remain along the edge of the rain shields currently
moving through central and eastern Kentucky at this time. The
low-level speed max is forecast to move across eastern Kentucky and
into southern West Virginia later this evening but the tornado
threat is expected to become marginal by then.

..Broyles/Hart.. 06/23/2017

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Mesoscale Discussion 1142
NWS Storm Prediction Center Norman OK
0725 PM CDT Fri Jun 23 2017

Areas affected...West Virginia...Maryland...Pennsylvania...New
Jersey...Delaware

Concerning...Severe Thunderstorm Watch 366...369...

Valid 240025Z - 240130Z

The severe weather threat for Severe Thunderstorm Watch 366, 369
continues.

SUMMARY...A severe threat is ongoing across parts of the
Mid-Atlantic early this evening. Damaging wind gusts or a brief
tornado will be possible but the severe threat is expected to
gradually diminish over the next couple of hours. Additional Weather
Watch issuance is not expected.

DISCUSSION...Radar imagery shows the remnants of Cindy across
central Kentucky with a band of convection extending to the
east-northeast across northern West Virginia, southern Pennsylvania
into northern New Jersey. Surface dewpoints along this corridor are
in the upper 60s and lower 70s F with the RAP showing moderate
instability mainly in the eastern part of the MCD area. This is
confirmed by the 00Z sounding at Washington DC which shows SBCAPE
near 1500 J/kg. This sounding also shows 0-6 km shear near 50 kt
along with 0-3 km storm relative helicity of 250 m2/s2. Low-level
shear is likely stronger westward into the northern part of West
Virginia. This is where a brief tornado will be possible over the
next hour or so with small discrete cells that rotate. A few strong
wind gusts will also be possible especially southeastern
Pennsylvania where a short line segment is ongoing. The severe
threat appears to be minimal and the watches will be allowed to
expire at 02Z. The situation will continue to be monitored in the
case that an isolated severe threat ramps up later this evening.

..Broyles/Hart.. 06/24/2017

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Mesoscale Discussion 1143
NWS Storm Prediction Center Norman OK
0726 PM CDT Fri Jun 23 2017

Areas affected...Southern AR...Far northeast TX...Far northern LA

Concerning...Severe Thunderstorm Watch 367...

Valid 240026Z - 240230Z

The severe weather threat for Severe Thunderstorm Watch 367
continues.

SUMMARY...Some isolated damaging wind gusts are possible for the
next few hours across southern AR and adjacent far northeast TX and
far northern LA . Anticipated limited and marginal nature of the
severe threat is expected to preclude the need for a downstream
watch.

DISCUSSION...Mesoscale convective system which has moved through AR
over the last several hours continues southward/southeastward into
southern AR and far northwest MS. Eastern portion of the system has
weakened considerably over the past hour as encountered the cloudy
and less unstable airmass over western TN and northwest MS. Western
portion of the system continues to forward propagate
southward/southwestward into the warm and unstable airmass of
south-central/southwest AR. Weak shear has prevent much organization
along this portion of the MCS with radar and satellite confirming
the outflow-dominant storm structures. This weakly organized,
outflow-dominant forward-propagation is expected to continue for at
least the next few hours as the downstream airmass remains
supportive of surface-based convection. Some isolated damaging wind
gusts are possible with these storms but the limited and marginal
nature of any severe threat precludes the need for a downstream
watch.

..Mosier.. 06/24/2017

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Mesoscale Discussion 1144
NWS Storm Prediction Center Norman OK
1225 AM CDT Sat Jun 24 2017

Areas affected...Central North Carolina

Concerning...Severe potential...Watch unlikely

Valid 240525Z - 240715Z

CORRECTED TO CHANGE WSR-88D VWP REFERENCE TO ROANOKE, VIRGINIA

Probability of Watch Issuance...20 percent

SUMMARY...An isolated wind damage threat may develop across central
North Carolina over the few hours. However, the threat is expected
to remain marginal and weather watch issuance is not expected.

DISCUSSION...Radar imagery shows the remnants of Cindy moving
eastward across the southern and central Appalachians. A couple
bands of convection are ongoing across western Virginia extending
southward into western North Carolina. The airmass ahead of this
convection is very moist with surface dewpoints in the 70s F across
much of North Carolina which is resulting in a corridor of moderate
instability across the Piedmont of North Carolina. MLCAPE values are
estimated in the 1000 to 2000 J/kg range from near the NC-SC
stateline extending northeastward into southeastern Virginia. In
addition, the WSR-88D VWP at Roanoke, VA shows a strong deep-layer
shear profile with 0-6 km shear of 50 to 55 kt and substantial speed
shear in the lowest 1km AGL. This appears representative of the
environment in central North Carolina and may support an isolated
wind damage threat as the line segment moves eastward into central
North Carolina over the next couple of hours. The latest CAM
solutions suggest that the line that is currently in west-central
North Carolina may persist for a couple more hours and then weaken.
This seems reasonable and weather watch issuance remains unlikely
due to the short duration that is expected for any wind damage
threat.

..Broyles/Dial.. 06/24/2017

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Mesoscale Discussion 1145
NWS Storm Prediction Center Norman OK
0554 AM CDT Sat Jun 24 2017

Areas affected...Portions of the Mid-Atlantic

Concerning...Severe potential...Watch unlikely

Valid 241054Z - 241200Z

Probability of Watch Issuance...5 percent

SUMMARY...Strong showers and storms may be capable of localized wind
damage and perhaps a brief tornado. However, the threat should be
too brief/localized for watch issuance.

DISCUSSION...As of 1045Z, a line of strong showers and thunderstorms
was quickly advancing across New Jersey and adjacent New York, aided
by a passing low-amplitude shortwave trough. KDIX VWP data indicate
a kinematic profile characterized by strong low/mid-level flow
upwards of 50-60 kt. In turn, precipitation-drag may transfer some
of this momentum to the surface, resulting in localized
gusty/damaging winds. However, the thermodynamic profile will remain
quite marginal for a more widespread threat. Additionally, while the
strength of the low-level shear may offer an opportunity for a brief
tornado, orientation of the low-level shear vectors is fairly
parallel to the convective line. As such, the tornado threat appears
quite marginal as well, and watch issuance will not be needed prior
to the line pushing offshore.

..Picca/Dial.. 06/24/2017

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Mesoscale Discussion 1146
NWS Storm Prediction Center Norman OK
0105 PM CDT Sat Jun 24 2017

Areas affected...Parts of the South Carolina piedmont into North
Carolina coastal plain

Concerning...Severe potential...Watch unlikely

Valid 241805Z - 242030Z

Probability of Watch Issuance...20 percent

SUMMARY...Thunderstorms accompanied by a risk for occasional
localized strong surface gusts may continue to develop through the
4-6 PM EDT time frame. Trends will continue to be monitored, but
the need for a watch is not currently anticipated.

DISCUSSION...Despite generally weak lower/mid tropospheric lapse
rates, a corridor of stronger pre-frontal boundary layer heating
(with surface temps around 90F) is contributing to moderate CAPE on
the order of 1500+ J/kg across parts of the South/North Carolina
piedmont into the North Carolina coastal plain. This is occurring
in the presence of seasonably high moisture content (lower/mid 70s
surface dew points and 2+ inch precipitable water), and a belt of
modest west southwesterly lower/mid tropospheric flow on the order
of 30 kt.

Deepening convective development is already evident within this
environment, downstream of a subtle mid-level impulse now beginning
to progress east northeast of the Georgia piedmont. And further
intensification seems likely through the peak afternoon heating.
Eventually, heavy precipitation loading and downward momentum
transfer may contribute to a risk for localized potentially damaging
wind gusts near the stronger activity. This could include small
upscale growing clusters, but the potential for the evolution of one
large well organized convective system seems low, and likely to
limit widespread severe weather potential.

..Kerr/Guyer.. 06/24/2017

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Mesoscale Discussion 1147
NWS Storm Prediction Center Norman OK
0242 PM CDT Sat Jun 24 2017

Areas affected...Portions of NM and far south-central CO

Concerning...Severe potential...Watch unlikely

Valid 241942Z - 242215Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated threat for large hail and strong to locally
damaging winds should persist through early evening. Watch issuance
is unlikely.

DISCUSSION...Beneath upper ridging centered over northern Mexico and
the Southwest, persistent weak low-level easterly flow across NM and
south-central CO is encouraging initially isolated convective
development across west-central NM. Additional thunderstorms are
expected to develop across NM this afternoon aided by terrain-driven
circulations. Visible satellite imagery shows almost total clearing
along and west of the central mountain chain of NM, and temperatures
have warmed into the 80s and lower 90s across lower terrain. Modest
low-level moisture characterized by upper 40s to lower 50s dewpoints
is present across this region, and combined with steep mid-level
lapse rates and diurnal heating, MLCAPE generally ranging 500-1000
J/kg has developed. Although mid-level northwesterly winds weaken
with southern extent across NM, there is sufficient mid-level flow
to support mainly 30-35 kt of effective bulk shear. This should be
sufficient to weakly organize thunderstorm updrafts, and isolated
instances of large hail and strong to locally damaging winds may
occur with any thunderstorms across this region through the
remainder of the afternoon and continuing into the early evening.
There may be some potential for loosely organized convective
clusters to develop and move southeastward across western/central
NM, perhaps posing a slightly greater wind threat with time.
Regardless, the overall severe threat will likely remain too
isolated to warrant watch issuance due to the marginal
thermodynamic/kinematic environment.

..Gleason/Guyer.. 06/24/2017
Dome, dome, dome..The life is a dome

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Ernest
Mensajes: 8130
Registrado: Vie Jul 17, 2009 10:54 pm
Ubicación: Villa Urquiza, Ciudad de Buenos Aires

Re: Seguimiento general en EEUU

Mensajepor Ernest » Mar Jul 18, 2017 6:31 pm

Nunca había escuchado la expresión "ring of fire", me resultó interesante.

https://www.wunderground.com/news/ring- ... t=K21G26Gz

Y este es del 15/7 creo. Nueve muertos tras una "flash flooding" en Arizona. Casi nada.

http://www.weathernationtv.com/news/9-d ... g-arizona/

Imagino que serán tormentas del estilo de las que tiene Córdoba en verano, no de esas de frentes estacionarios kilométricos que le gustan a Albert.
Did you want to talk about the weather, or were you just making chitchat?

Mi página en facebook: MeteoMundo

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Ezequiel15
Mensajes: 9217
Registrado: Lun Ene 23, 2012 4:18 pm
Ubicación: Isidro Casanova (Oeste GBA).
Contactar:

Re: Seguimiento general en EEUU

Mensajepor Ezequiel15 » Dom Ago 06, 2017 10:35 am

In GFS we don't trust
Los datos que escribo en Clima siempre son de OCBA.

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federico
Mensajes: 5373
Registrado: Vie Ago 07, 2009 9:49 pm
Ubicación: jose leon suarez, buenos aires

Re: Seguimiento general en EEUU

Mensajepor federico » Sab Ago 19, 2017 9:38 pm

Durante el eclipse total que va a suceder el lunes se va a ir correr un modelo que vaya asimilando la variación de la radiación para ver cómo afecta el eclipse a la atmósfera.

http://research.noaa.gov/News/NewsArchi ... ather.aspx

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Chuekin
Mensajes: 1327
Registrado: Dom Oct 04, 2009 6:09 pm
Ubicación: Monte Castro, CABA
Contactar:

Re: Seguimiento general en EEUU

Mensajepor Chuekin » Dom Ago 20, 2017 1:35 pm

federico escribió:Durante el eclipse total que va a suceder el lunes se va a ir correr un modelo que vaya asimilando la variación de la radiación para ver cómo afecta el eclipse a la atmósfera.

http://research.noaa.gov/News/NewsArchi ... ather.aspx


Fabuloso, además van a disponibilizar los datos en tiempo real.
We in the field know that GFS 10+ day forecasts are "fantasy land"

Hay que dejar de decirle CHUVA al WRF por dos años (?)

-Martin


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