Seguimiento general en EEUU

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jotape
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Re: Seguimiento general en EEUU

Mensajepor jotape » Mié Abr 12, 2017 7:42 am

Jajaja ponete las pilas Roberto (?)

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mié Abr 12, 2017 7:44 am

jotape escribió:Jajaja ponete las pilas Roberto (?)

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Esta el espiritu de el. Es como el "Comandante" :D
Dome, dome, dome..The life is a dome

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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Jue Abr 20, 2017 7:07 pm

Tras un breve descanso, regreso con los seguimientos de Estados Unidos. Los últimos días, no han sido muy entretenidos, aunque ayer hubo un tornado watch y un enhanced. Muy aburridas las cosas por el sur y sudeste del país. Ahora mismo, hay un frente frío avanzando sobre los Grandes Lagos hasta Oklahoma, dejando la activación de algunas tormentas severas aisladas. Hay un severe thunderstorm watch para Indiana, Ohio y Michigan.
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Discusión.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Thu Apr 20 2017

Valid 202000Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF THE LOWER GREAT LAKES REGION
AND OHIO VALLEY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS
PARTS OF THE SOUTH CENTRAL PLAINS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS
SURROUNDING AREAS OF THE GREAT LAKES AND OHIO VALLEY INTO SOUTHERN
PLAINS...

...SUMMARY...
Severe storms capable of producing damaging winds and hail remain
possible across parts of the southern Great Lakes region and Ohio
Valley late this afternoon and early evening. Isolated severe storms
capable of producing large hail are also possible across parts of
the southern Plains tonight.

...20Z Outlook Update...
Steeper isentropic ascent (mainly associated with warm advection in
the 850-700 mb layer) appears generally focused well to the
north/cool side of a fairly sharp surface frontal zone now extending
from parts of southeastern lower Michigan through the Lake Erie
vicinity (on into northern Pennsylvania). This would seem to
provide the forcing needed to support any substantive upscale
convective growth late this afternoon and evening. Given the
displacement from the warm/moist sector boundary layer air,
consolidation of ongoing activity (across the Great Lakes/Ohio
Valley region) into one large convective cluster appears unlikely.

Although the potential for the evolution of a significant organizing
convective system seems to be diminishing, the development of a
small convective cluster along the shallow residual frontal zone
across Lake Erie may not be out of the question. In the presence of
30-50 kt westerly deep layer mean flow, this may be accompanied by a
risk for potentially damaging wind gusts, mainly along the southern
Lake Erie shore, into and through the Cleveland OH area late this
afternoon.

Otherwise, scattered vigorous thunderstorm development may be
accompanied by a risk for potentially damaging wind gusts, mainly
along/ahead of the eastward and southeastward advancing cold front,
across the Ohio Valley.

No changes have been made to the remainder of the outlook.

..Kerr.. 04/20/2017

.PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Apr 20 2017/

...Ohio Valley/Great Lakes area this afternoon...
A midlevel shortwave trough over the upper MS Valley will progress
eastward today over the Great Lakes, as an associated surface
cyclone develops east-northeastward across Lower MI along a surface
warm front. The warm front will move into southern Lower MI this
afternoon, and south of the boundary the warm sector will be
characterized by surface temperatures in the 75-80 F range with
dewpoints in the upper 50s to lower 60s. Midlevel lapse rates will
remain modest (near 6.5 C/km), which will limit MLCAPE to near 1000
J/kg. The surface cold front should provide a focus for the
development of clusters of storms/line segments by early afternoon
across IN/southern Lower MI, with convection subsequently spreading
eastward across OH this afternoon. Other storm clusters may also
form along the warm front farther east into northwest PA and western
NY.

The weak-moderate buoyancy, steep low-level lapse rates with daytime
heating, and deep unidirectional wind profiles will favor damaging
winds as the primary risk, though isolated/marginally severe hail
will also be possible. An isolated tornado cannot be ruled out with
storms interacting with the warm front, where low-level shear will
be stronger.

...Northwest TX this afternoon/evening...
Surface heating south of a slow-moving front and boundary-layer
dewpoints in the 60s will contribute to moderate buoyancy, and
shallow ascent along the front may be sufficient to initiate
isolated storms this afternoon. Marginal supercell structures will
be possible since this area is along the southern fringe of the
midlevel westerlies, and as low-level southerly flow begins to
increase this evening. Isolated large hail/damaging winds will be
possible.

...Central/western OK to the TX Panhandle overnight...
Numerous elevated thunderstorms will likely develop early tonight
across western/central OK in a strengthening warm-advection regime
atop a shallow cool air mass, north of a cold front that is expected
to stall this evening from south central OK into NW TX. Mid 60s
boundary-layer dewpoints south of the front and midlevel lapse rates
in excess of 7.5-8 C/km will contribute to MUCAPE in excess of 1500
J/kg rooted near 850 mb. Large hail will be the primary risk,
especially with any elevated supercells given effective bulk shear
in excess of 40 kt. Convection will likely persist through the
overnight hours, with additional storm development expected farther
west into the TX Panhandle as a midlevel trough now over the Great
Basin approaches the southern High Plains.

PRÓXIMA ACTUALIZACIÓN: 01:00Z.
-----------------------------------------------
SEVERE THUNDERSTORM WATCH.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 151
NWS Storm Prediction Center Norman OK
205 PM EDT Thu Apr 20 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Northeast Indiana
South central and southeast Lower Michigan
Northwest Ohio
Lake Erie

* Effective this Thursday afternoon and evening from 205 PM until
800 PM EDT.

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

SUMMARY...Clusters of strong/severe storms will continue to develop
through the afternoon from Indiana into southern Lower Michigan and
northwestern Ohio. Occasional damaging gusts and large hail will be
the main concerns through the afternoon and into this evening.

The severe thunderstorm watch area is approximately along and 80
statute miles east and west of a line from 15 miles northwest of
Detroit MI to 50 miles south southwest of Findlay OH. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
26030.

...Thompson

--------------------------------------
DISCUSIÓN A MESOESCALA.
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Mesoscale Discussion 0528
NWS Storm Prediction Center Norman OK
0331 PM CDT Thu Apr 20 2017

Areas affected...Parts of Indiana/Ohio/southern Lower Michigan

Concerning...Severe Thunderstorm Watch 151...

Valid 202031Z - 202230Z

The severe weather threat for Severe Thunderstorm Watch 151
continues.

SUMMARY...Isolated severe risk continues in and near WW #151.

DISCUSSION...Latest radar loop shows several bands of storms moving
across southern Lower Michigan/Indiana/western Ohio at this time,
with a new band of storms developing along the immediate frontal
zone. This band of storms -- now entering northwest portions of WW
#151 -- likely marks the back edge of severe risk, which will
gradually advance eastward across the watch over the next few hours.
Meanwhile, risk for locally damaging winds and hail continues, as
an amply sheared and unstable warm sector remains in place in and
near the WW area.

..Goss.. 04/20/2017
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 Abr 20, 2017 8:40 pm

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Mesoscale Discussion 0529
NWS Storm Prediction Center Norman OK
0540 PM CDT Thu Apr 20 2017

Areas affected...Northwest TX...OK

Concerning...Severe potential...Watch possible

Valid 202240Z - 210015Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorms are expected to develop across northwest TX
into central OK this evening. Large hail is the primary risk with
this activity.

DISCUSSION...Surface front has stalled from east central OK into
northwest TX early this evening. With surface temperatures in the
mid 80s across northwest TX a corridor of modest instability has
developed from the TX South Plains to near the Red River. Latest
visible satellite imagery depicts a thickening CU field along the
front with deeper convection over Haskell/Knox Counties in TX
producing weak echo returns. As LLJ strengthens across this region
into southwest OK this evening it appears a marked increase in
thunderstorm activity will be observed. Numerous elevated
thunderstorms should blossom north of the boundary and adequate
mid-level lapse rates are in place for robust updrafts. Greatest
risk with this activity should be hail.

..Darrow/Dial.. 04/20/2017

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Mesoscale Discussion 0530
NWS Storm Prediction Center Norman OK
0601 PM CDT Thu Apr 20 2017

Areas affected...Eastern IN...Southeast MI...Northwest OH

Concerning...Severe Thunderstorm Watch 151...

Valid 202301Z - 210000Z

The severe weather threat for Severe Thunderstorm Watch 151
continues.

SUMMARY...Scattered thunderstorms, a few severe, will continue
across the southeastern half of WW151 this evening.

DISCUSSION...Considerable convective overturning has occurred across
much of the OH Valley this evening. In the absence of significant
buoyancy, stronger low-level forcing along the cold front should
serve as the primary focus for most organized thunderstorms over the
next few hours. With onset of diurnal cooling it appears the
greatest risk will be marginally severe hail and locally gusty
winds.

Just south of the watch over southern IN, a small cluster of
strong/severe thunderstorms has developed. This activity has
evolved within slightly more unstable air mass where influence from
earlier convection was less disruptive. Even so, marginally severe
hail and gusty winds should be the primary threats as this
convection spreads toward southwest OH.

..Darrow.. 04/20/2017
Dome, dome, dome..The life is a dome

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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Vie Abr 21, 2017 9:44 am

Y desde temprano, activo Oklahoma.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 153
NWS Storm Prediction Center Norman OK
415 AM CDT Fri Apr 21 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Western and central Oklahoma
Texas and Oklahoma Panhandles

* Effective this Friday morning from 415 AM until NOON CDT.

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

SUMMARY...Hail potential will increase over the watch area the next
few hours as scattered thunderstorms continue to develop and
increase in coverage from the Panhandles into western Oklahoma.
Activity should coalesce into a semi-elevated, forward-propagating
storm complex through mid-morning, sweeping east or east-southeast
across western/central Oklahoma, with an increasing threat for
severe gusts as the complex gets better-organized and approaches a
surface front.

The severe thunderstorm watch area is approximately along and 60
statute miles either side of a line from 20 miles west northwest of
Dalhart TX to 35 miles south of Chandler OK. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

OTHER WATCH INFORMATION...This severe thunderstorm watch replaces
severe thunderstorm watch number 152. Watch number 152 will not
be in effect after 415 AM CDT.

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
28030.

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

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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Vie Abr 21, 2017 11:43 am

Recién actualizado el convective outlook de hoy.
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DISCUSIÓN.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Fri Apr 21 2017

Valid 211300Z - 221200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
SOUTH-CENTRAL/SOUTHEASTERN OKLAHOMA AND NORTH-CENTRAL/NORTHEAST
TEXAS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ELSEWHERE FROM
WESTERN OKLAHOMA TO NORTH TEXAS AND CENTRAL ARKANSAS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK...AND EXTENDING ACROSS THE MID-SOUTH TO PARTS OF THE
COASTAL MID-ATLANTIC...

...SUMMARY...
Severe thunderstorms may offer damaging gusts, large hail and a few
tornadoes through tonight from parts of the southern Plains into the
Ozark Plateau. Isolated severe thunderstorms may also impact
portions of the Mid-South into the Mid-Atlantic with wind and hail.

...Synopsis...
The mid/upper levels will be characterized by a complex pattern,
involving split flow downstream from a negatively tilted trough now
located over the Rockies. A leading/northern-stream perturbation --
now evident in moisture-channel imagery over the upper Great Lakes
and northern ON -- is forecast to migrate eastward to QC through the
period, with a trailing trough back southwestward over OH at 12Z.
Upstream shortwave ridging over the northern Plains will form a
temporarily closed 500-mb high over the Dakotas, as a segment of the
Rockies trough undercuts it and moves across the central Plains.
Late in the period, that high will devolve back to a shortwave ridge
and begin to phase with progressive ridging over the Great Basin and
northern Rockies. Meanwhile another vorticity max over the northern
Rockies should dig southeastward.

The net result of all this height and vorticity rearrangement, by
the end of the period, should be a small mid/upper-level cyclone
moving from southern KS to southern/western MO, with a trough
west-northwestward across KS to a secondary low/vorticity max over
northern CO and southern WY. The nose of a cyclonically curved,
110-120-kt 250-mb jet streak will shift eastward across the southern
High Plains and western OK by 00Z. By 12Z, that jet streak will
arch from the lower Ohio Valley across OK to CO and western WY.

At the surface, a cold front associated with the Great Lakes trough
extended from northern/western PA southwestward across eastern KY
and western TN, becoming a stationary to slowly moving warm front
fro central AR across extreme southern OK, through a weak
frontal-wave low near FDR, and another low near the southeastern
corner of NM. This front will be reinforced by outflow from
convection that will sweep east-southeastward across OK this morning
into afternoon, as discussed below. Late this afternoon, a
frontal-wave low should form over eastern OK, moving to parts of
central/northeastern AR by 12Z with the front trailing across east
TX, south-central TX, and the Big Bend region. The front will
intersect a dryline this afternoon over the Big Country region of
west-central TX, then overtake the dryline as it plunges southward
through the Edwards Plateau overnight.

...Southern Plains to AR...
An organizing, initially elevated MCS -- moving east-southeastward
from the TX Panhandle over western OK -- will present a risk for
large hail this morning. Also, an increasing threat for severe
gusts is expected as the forward-propagational cold pool gets better
organized and approaches progressively higher-theta-e, less-stable
air nearer to the front. See SPC watch 153 and related mesoscale
discussions for near-term details. Also, clusters of thunderstorms
with isolated, embedded severe hail cores and gusts approaching
severe limits are ongoing over parts of central OK and western AR,
and will continue to offer a threat for sporadic severe while
shifting eastward through the remainder of the morning.

With time, the MCS will progress further across central and eastern
OK, becoming closer to surface-based as it encounters destabilizing
air near the surface. Additional thunderstorms are expected to
develop this afternoon over southern OK and north-central TX near
the Red River, along the effective, cold-pool-augmented frontal
surge extending southwest from the complex. The environment into
which this activity will move will be favorable for all severe
threats from supercells, bows and clustered modes.

The environment along and south of the frontal zone will be
characterized by strengthening vertical shear and large-scale
ascent, as well as pockets of diabatic heating amidst surface dew
points in the 60s F. This will contribute to a very favorable
parameter space for supercells and at least a few tornadoes, with
large low-level hodographs, effective SRH 200-500 J/kg,
effective-shear magnitudes 60-65 kt, and MLCAPE around 2000 J/kg.
Any relatively discrete and sustained supercell impinging on that
sort of parameter space could produce a significant tornado as well
as very large/damaging hail. However, the significant-tornado risk
still remains too conditional and uncertain for an areal sig-tornado
outlook due to concerns over:
1. The surging cold front/outflow and its potential interaction
with/undercutting of storms, and
2. Potential for convective mode to get rather clustered and messy
near the front, even without direct undercutting of updrafts by the
cold surge itself.
The severe potential should wane after about 06Z as the regime
becomes more anafrontal and the remaining convection encounters a
stabilizing boundary layer.

...Mid-South to Mid-Atlantic...
Widely scattered to scattered thunderstorms are expected to develop
this afternoon near the front, with more isolated coverage in the
warm sector. Activity should develop and intensify in a modestly
capped, destabilizing air mass characterized by surface dew points
generally in the mid 50s to low 60s (locally higher), offsetting
weak mid/upper-level lapse rates enough for 500-1500 J/kg MLCAPE.
Pockets of relatively sustained surface diabatic heating and
well-mixed subcloud layers will favor strong/isolated damaging
downdrafts. Weak near-surface winds with a substantial westerly
component will restrict low-level shear; however, sufficient flow
aloft should exist for around 30-40 kt effective-shear magnitudes in
some areas, in support of multicellular to marginally/briefly
supercellular organization. As such, a few severe hail reports also
cannot be ruled out.

..Edwards/Dean.. 04/21/2017

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Mesoscale Discussion 0534
NWS Storm Prediction Center Norman OK
0754 AM CDT Fri Apr 21 2017

Areas affected...Western and central OK

Concerning...Severe Thunderstorm Watch 153...

Valid 211254Z - 211500Z

The severe weather threat for Severe Thunderstorm Watch 153
continues.

SUMMARY...Potential exists for an increasing risk for damaging winds
across western into central Oklahoma this morning. Prior to the
line of storms moving into central OK later this morning, hail will
remain the primary threat with the cluster of ongoing storms.

DISCUSSION...12Z surface analysis indicated relatively strong
pressure rises centered on Gage, OK with a 4.5 mb pressure rise in 2
hours, while 2-3 mb pressure falls persisted across central OK.
Trends in mosaic radar imagery showed a band of storms, extending
from Alfalfa County OK to Beckham County OK had increased its
forward speed to around 40 kt. A continuation of surface pressure
rises behind this line should aid in sustaining the forward speed,
with the potential for an increasing threat for damaging winds.
Current track of this band suggests damaging winds should reach the
OKC metro area between 14-15Z.

Meanwhile, isolated severe hail will remain a primary threat with
ongoing elevated storms centered over the OKC metro area. 12Z
surface analysis indicated these storms were located well north of a
stationary boundary extending generally east to west across extreme
southern OK near the Red River. A 40-50 kt southerly low-level jet
is sustaining sufficient low-level warm advection north of this
boundary. This combined with MUCAPE of 1000-1500 J/kg, 40-50 kt of
effective bulk shear, and steep midlevel lapse rates favor the hail
threat.

..Peters.. 04/21/2017
Dome, dome, dome..The life is a dome

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Sab Abr 22, 2017 3:32 pm

El frente que ayer estuvo causando tiempo severo en Oklahoma, Arkansas y Texas, se espera que hoy afecte a gran parte del sur de los Estados Unidos. Viento y granizo, los riegos mas importantes.
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% de vientos(entre 5 a 15%).
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% de granizo(5 a 15%).
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DISCUSIÓN.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1123 AM CDT Sat Apr 22 2017

Valid 221630Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
LOWER MISSISSIPPI AND TENNESSEE VALLEYS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN
VIRGINA AND NORTHERN NORTH CAROLINA...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ELSEWHERE FROM
LOUISIANA TO THE VIRGINIA/NORTH CAROLINA BORDER REGION...

...SUMMARY...
A few severe thunderstorms capable of damaging wind gusts and large
hail will be possible this afternoon and evening from Louisiana to
the southeastern Virginia/North Carolina Tidewater region. The
best-organized potential appears to be from parts of Mississippi
into western/northern Alabama and southern Tennessee, and over
southern Virginia and extreme northern North Carolina.

...Mississippi and Tennessee Valleys...
A well-defined vorticity maximum over Missouri is forecast by model
guidance to move eastward over the Mississippi Valley tonight as the
associated upper trough amplifies during the period. A strong band
of mid/upper level winds is located on the southern periphery of the
system with a 60-70 kt mid-level jet streak progressing toward the
lower Mississippi Valley.

At the surface, a low near the Mississippi Delta will move slowly
eastward across northern parts of Mississippi and Alabama through
tonight, as a trailing cold front moves southeastward across the
lower Mississippi Valley. A quasistationary front extending eastward
from the low is forecast to sag slowly southward with time.

Earlier clouds over northern/central Mississippi into northern
Alabama and southern middle Tennessee have diminished substantially
permitting stronger diabatic heating to occur in advance of the
approaching cold front. With surface temperature warming into the
70s and dew point values in the low-mid 60s, further destabilization
is likely in the pre-frontal environment with MLCAPE reaching
1000-1500 J/kg this afternoon. CAM guidance indicates stronger
storms will develop along/ahead of the cold front during the early
afternoon with activity spreading eastward through the evening
hours. Effective bulk shear of 35-40 kt will promote organized
storm structures including isolated supercells. Stronger cells will
be capable of producing mainly damaging wind gusts and severe hail.

...Southern Virginia/Northern North Carolina...
The environment is undergoing strong diabatic heating over North
Carolina where visible satellite imagery indicates few clouds, and
low-level warming is spreading northward into far southern Virginia
as cloud cover thins near an east-west frontal zone. Despite modest
mid-level lapse rates, surface dew points in the low-mid 60s coupled
with diurnal heating will result in further destabilization with
MLCAPE near 1500 J/kg expected this afternoon. Storms are beginning
to develop at this time over northwest North Carolina and southwest
Virginia within a weakly-capped environment. Activity is expected
to increase in coverage and intensity and spread/develop eastward
during the afternoon with a few severe storms possible. See
Mesoscale Discussion 545 for more details.

..Weiss/Cook.. 04/22/2017

Discusiones a mesoescala del día de hoy.
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Mesoscale Discussion 0545
NWS Storm Prediction Center Norman OK
1057 AM CDT Sat Apr 22 2017

Areas affected...Southern Virginia and northern North Carolina

Concerning...Severe potential...Watch possible

Valid 221557Z - 221800Z

Probability of Watch Issuance...40 percent

SUMMARY...Scattered thunderstorms are expected to develop early this
afternoon, and a few of the storms could produce damaging gusts and
marginally severe hail. This area will continue to be monitored
through the afternoon, though the need for a watch is unclear.

DISCUSSION...Differential surface heating and a slow-moving front
across southern VA will likely focus thunderstorm initiation early
this afternoon. Visible satellite imagery shows cumulus development
near the NC/VA border in a zone of differential heating, where
surface observations show temperatures warming into the mid-upper
70s with dewpoints in the mid 60s. 12z soundings revealed rather
modest midlevel lapse rates over this area, but continued surface
heating will boost MLCAPE into the 1000-1500 J/kg range, and a lack
of convective inhibition should allow scattered thunderstorm
development early this afternoon. Some increase in storm coverage
may also be related to a band of ascent spreading east of the
southern Appalachians, in association with a weak convectively
enhanced midlevel trough.

There is some enhancement to low-level shear on the immediate cool
side of the front sagging southward across southern VA, but wind
profiles will remain largely unidirectional with effective bulk
shear of 35-40 kt near and south of the front. Thus, a few
organized storms/clusters, potentially with some supercell
structures, will pose a primary risk for damaging winds this
afternoon. The scenario appears marginal for a severe thunderstorm
watch at this time, though the area will continue to be monitored.

..Thompson/Weiss.. 04/22/2017

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Mesoscale Discussion 0546
NWS Storm Prediction Center Norman OK
1251 PM CDT Sat Apr 22 2017

Areas affected...Central Louisiana northeastward to northwestern
Alabama and Middle Tennessee

Concerning...Severe potential...Watch possible

Valid 221751Z - 221945Z

Probability of Watch Issuance...40 percent

SUMMARY...Damaging wind gusts and hail approaching 1" in diameter
are all possible with storms developing across the region this
afternoon. A WW is being considered.

DISCUSSION...Scattered thunderstorms are continuing to increase
across the discussion area just ahead of a surface boundary
extending from Middle Tennessee, through the Mississippi Delta, and
southwestward into northern Louisiana. The airmass ahead of this
frontal boundary was weakly capped, with insolation/surface warming
and weak low-level warm advection fostering weak to moderate
instability in an axis from central Louisiana northeastward to
Middle Tennessee. Stronger instability was common in southwestern
portions of the discussion area (1500-2000 J/kg MUCAPE), with
gradually weaker instability (500 J/kg MUCAPE) area near Nashville.
Westerly deep shear (around 35 knots) was sufficient for storm
organization, and weak surface convergence combined with ascent
associated with a mid-level low north of the area should foster
gradually increasing convective coverage and intensity with
progression toward peak heating later this afternoon. Hail and
gusty winds will be the primary threats with this activity.

Given the aforementioned scenario, a WW issuance is being considered
for portions of the region.

..Cook/Weiss.. 04/22/2017
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 Abr 22, 2017 4:23 pm

Y ya tenemos el primer Severe Thunderstorm Watch de la tarde. Ya hay algunos tornado warnings en el sur de Virginia.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 157
NWS Storm Prediction Center Norman OK
305 PM EDT Sat Apr 22 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Northern North Carolina
Southern Virginia


* Effective this Saturday afternoon and evening from 305 PM until
900 PM EDT.

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

SUMMARY...A line of strong storms is moving eastward into south
central Virginia and northwest North Carolina, while new storms are
developing in advance of the squall line. Storms are expected to
gradually intensify and produce a threat for damaging wind gusts and
large hail.

The severe thunderstorm watch area is approximately along and 80
statute miles east and west of a line from 35 miles north northeast
of South Hill VA to 40 miles south of Danville VA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...



&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
26030.

...Weiss
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 Abr 22, 2017 4:51 pm

Les dejo la reciente actualizacion del convective outlook de hoy. Muy nulos los cambios. Lo unico que cambio un poco, es el area de riesgo Marginal. El resto, casi todo igual.
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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Sab Abr 22, 2017 5:01 pm

Se confirma tornado al norte de Marietta, noreste de Mississippi. ¡Terrible hook echo!
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