Seguimiento general en EEUU

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stormchaserAlberto
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mar Abr 04, 2017 1:26 pm

Se vienen unas 48 horas muy activas en gran parte del sudeste de los Estados Unidos. Hay riesgo moderado para mañana, esperandose violentos tornados. Vamos con el dia 1.
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% de tornados. Las mayores probabilidades, estan entre las costas del Golfo entre Mississippi, Louisiana, Alabama y el noroeste de Florida. Para esas zonas, recien se esperan algunas activaciones durante la madrugada(bien temprano, alrededor de las 7AM CDT), con el avance de un frente calido hacia el norte.
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% de vientos.
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% de granizo. Mayores chances entre el noreste de Oklahoma y el sudoeste de Missouri.
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Discusion:
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Tue Apr 04 2017

Valid 041300Z - 051200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FROM NORTHEAST OKLAHOMA INTO SOUTHWEST MISSOURI...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT FROM CENTRAL/EASTERN OKLAHOMA TO NORTHWESTERN ARKANSAS
AND CENTRAL MISSOURI...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE TONIGHT
ACROSS PARTS OF THE NORTH CENTRAL/NORTHEAST GULF COAST...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
PLAINS/OZARKS SLIGHT RISK...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS NORTH
FLORIDA TODAY...AND FROM SOUTHEAST LOUISIANA AND NORTHERN
ALABAMA/NORTHWESTERN GEORGIA LATE TONIGHT...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
ACROSS EASTERN PENNSYLVANIA AND VICINITY...

...SUMMARY...
Scattered strong to severe thunderstorms will be possible across
parts of the south-central Plains into the Ozarks this afternoon and
early evening, and across parts of the central Gulf Coast states
late tonight into early Wednesday morning. Isolated strong storms
will also be possible today across part of north Florida and in the
vicinity of eastern Pennsylvania.

...I-44 corridor from northeast OK into MO this evening...
A compact midlevel shortwave trough over northern NM this morning
will progress eastward to central OK this evening and the Ozarks
overnight. An associated surface cyclone initially in northwest TX
will develop northeastward along a stalled front near I-44 in OK, in
advance of the midlevel trough. Strengthening wind profiles and
ascent will immediate precede the midlevel trough and surface
cyclone and support strong-severe thunderstorm development this
afternoon in OK, and the storms will spread into MO/AR overnight.

The primary limiting factor to a more robust severe-weather risk
will be marginal moisture return in the warm sector of the cyclone.
The maritime tropical air mass was shunted southward into the north
central and northwest Gulf of Mexico by the system the prior two
days. Residual boundary layer dewpoints in the low-mid 50s, aided
some today by evapotranspiration but offset by vertical mixing, are
expected up to the stalled front from central OK into southwest MO
by mid-late afternoon. This moisture, along with afternoon surface
temperatures in the 70s and midlevel lapse rates of 8 C/km or
greater, will drive MLCAPE of 1000-1500 J/kg. This buoyancy,
combined with effective bulk shear in excess of 50 kt, and
relatively cool midlevel temperatures, will support a risk for
supercells with large hail near and just ahead of the surface
cyclone/triple point in beginning 21-23z in OK and continuing into
MO through late evening. Storms may also develop southward along
the cold front into eastern OK and northwestern AR, though the
strongest/most persistent storms are expected along the path of the
cyclone along the I-44 corridor from northeast OK into southwest MO
through early tonight.

The tornado risk is limited mostly by the marginal low-level
moisture. There might be a narrow zone along the stalled front
(immediately ahead of the surface cyclone) where moisture will be
sheltered some from vertical mixing, and where low-level hodographs
will by the largest with the most streamwise vorticity. A discrete
storm moving along this narrow zone could produce a tornado before
near-surface cooling/stabilization ends the threat just after
sunset.

...North central Gulf coast into Dixie early Wednesday...
In response to cyclogenesis with the shortwave trough approaching
the Ozarks, the maritime tropical air mass will return northward
late tonight and early Wednesday in a strengthening warm advection
regime. Elevated thunderstorm development is expected from 06-12z
from southeast LA into at least central AL. Large hail will be the
main risk early Wednesday across the northern parts of the Slight
Risk area. Farther south near the surface warm front, some of the
convection could become rooted near or at the surface. Deep-layer
and low-level shear will favor supercells, and profiles will become
supportive of some tornado and/or damaging wind risk from 09-12z.
The main uncertainties will be the specific corridor of storm
development and the narrow time window for surface-based storms.
Thus, 5% tornado probabilities appear most appropriate within this
outlook period.

...North FL today...
A lingering band of storms along a composite outflow boundary will
sag southward through the day across north FL. Isolated strong
gusts will be possible the first half of the day within this band,
before the convection weakens.

...Eastern PA and vicinity this afternoon...
A midlevel trough and an associated/diffuse surface trough will
cross PA during the day. Lingering low-level moisture and some
surface heating will contribute to weak surface-based instability
across this area by midday/early afternoon, and will be sufficient
for at least isolated thunderstorm development. Given somewhat cool
midlevel temperatures and effective bulk shear of 30-40 kt, a
low-end hail/wind risk will be possible this afternoon with the
stronger/more organized cells.
..Thompson/Goss.. 04/04/2017

Se actualiza en unos minutos(16:30z). Si hay cambios, lo estare posteando de vuelta.
------------------------------------------------------------------------------
Y ahora, vamos con el dia 2. Muy interesante el panorama, con un frente calido activando en la madrugada, con un mejoramiento temporario luego y una explosion convectiva muy intensa durante la tarde. Por el momento, hay riesgo moderado.
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Probabilidades de tiempo severo.
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Discusion:
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Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Tue Apr 04 2017

Valid 051200Z - 061200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO
WEDNESDAY NIGHT ACROSS MUCH OF SOUTHERN AND EASTERN ALABAMA AND THE
WESTERN FLORIDA PANHANDLE TROUGH GEORGIA AND PORTIONS OF WESTERN
SOUTH CAROLINA...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
SURROUNDING AREAS OF THE EASTERN GULF AND SOUTH ATLANTIC COAST
STATES...NORTHWARD THROUGH THE TENNESSEE AND LOWER OHIO VALLEYS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING
AREAS OF THE SOUTHEAST AND THE OHIO VALLEY INTO THE APPALACHIANS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS AS FAR WEST AS
PORTIONS OF THE LOWER AND MIDDLE MISSISSIPPI VALLEY...AS FAR NORTH
AS THE SOUTHERN GREAT LAKES REGION AND AS FAR EAST AS PORTIONS OF
THE MID ATLANTIC COAST STATES...

...SUMMARY...
An outbreak of severe thunderstorms is possible across much of the
Southeast, northward along and west of the Appalachians into the
Ohio Valley, Wednesday through Wednesday night. This is expected to
include supercell development with a risk for tornadoes, some of
which could become strong and long-lived, particularly across parts
of the Southeast.

...Synopsis...
Amplification within the westerlies now appears underway across the
eastern Pacific through the Pacific Coast region, and is expected to
gradually translate eastward across and east of the Rockies through
this forecast period. As large-scale ridging builds across the U.S.
Rockies and Canadian Prairies, large-scale downstream troughing is
forecast to continue to evolve east of the high Plains through the
vicinity of the Appalachians by 12Z Thursday.

Models indicate that significant surface cyclogenesis will already
be well underway by 12Z Wednesday across southern Missouri,
associated with a vigorous short wave impulse within the southern
stream of split westerlies, and forecast to turn northeast of the
southern Rockies today. Guidance indicates at least some
interaction or phasing of the two streams is possible Wednesday into
Wednesday night, with at least one northern stream impulse digging
(across the northern Plains/mid Missouri Valley) into the evolving
larger scale upper troughing by the end of the period. This
interaction remains a point of model uncertainty, and will have an
impact on the track and rate of deepening of the surface cyclone.
Regardless, the models generally indicate at least slow further
deepening, as the low migrates through the lower Ohio Valley into
the upper Ohio Valley/lower Great Lakes region by 12Z Thursday.

South of the cyclone, an associated cold front is expected to
eventually surge east of the Mississippi Valley through the
Appalachians. Low-level moisture will still be in the process of
returning ahead of the front, in the wake of a prior system. This
remains the primary uncertainty which could temper the overall
severe weather potential somewhat, as the environmental conditions
associated with evolving synoptic system appear otherwise favorable
for an outbreak of severe storms over a broad area east of the
Mississippi Valley into the vicinity of the Appalachians. And
confidence in sufficient moistening and destabilization are
increasing.

...Southeast...
Greatest confidence in substantive boundary layer moistening still
appears across portions of the eastern Gulf states into the south
Atlantic Coast states. Vigorous convective development may be
ongoing at 12Z Wednesday inland of the northeast Gulf coast, in
response to destabilization associated with the moistening, and
large-scale ascent associated with low-level warm advection. Models
are suggestive that forcing for this activity will be aided by a
high-level subtropical speed maximum, which may contribute to an
increase in coverage through the day, within the northeastward
advecting plume of richer precipitable water content.

In the presence of at least modestly steep mid-level lapse rates,
and wind profiles becoming characterized by strong deep layer shear
and sizable low-level hodographs, considerable organized severe
weather potential appears to exist. This is expected to include
discrete supercells accompanied by the risk for large hail and
tornadoes. In the wake of initial convective development expected
to spread northward across and to the lee of the southern
Appalachians during the day, guidance suggests new discrete storm
development is possible within a low-level confluence zone across
southern/eastern Alabama into western Georgia, with the environment
ahead of this activity possibly becoming conducive to long-lived
supercells with potential for strong tornadoes.

Additional pre-frontal storm development is also possible to the
west of this activity Wednesday afternoon into Wednesday evening.

...Ohio/Tennessee Valleys...
Confidence is increasing in warm sector moisture return that will
become supportive of weak to moderate CAPE, within at least a narrow
pre-frontal plume overspreading the region from west to east
Wednesday afternoon and evening. Aided by forcing within the exit
region of a 70-90 kt cyclonic 500 mb jet, and strengthening of
southerly 850 mb flow to 30-50 kt within the warm sector, the
environment is expected to become conducive to discrete supercell
storm development, at least initially. This is expected to be
accompanied by a risk for large hail and a few tornadoes, some of
which could be strong. Eventually, large-scale forcing may support
upscale growing lines or clusters of storms accompanied by a more
substantive risk for damaging wind gusts.
..Kerr.. 04/04/2017

Lo van a actualizar nuevamente a las 14:30(17:30z).
---------------------------------------------------------------
Les dejo la reciente actualización para el dia de hoy. Se mantiene todo prácticamente igual, salvo que aparecio un 5% de probabilidades de tornados en el este/noreste de Oklahoma.
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% de tornados.
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% de vientos.
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% de granizo.
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Discusion.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1125 AM CDT Tue Apr 04 2017

Valid 041630Z - 051200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
NORTH-CENTRAL AND NORTHEAST OK...SOUTHEAST KS...AND SOUTHWEST MO...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
OK...KS...AR...MO...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
CENTRAL GULF STATES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER
NORTH-CENTRAL FL...

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

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
PA/NJ/NY...

...SUMMARY...
Scattered strong to severe thunderstorms will be possible across
parts of the south-central Plains into the Ozarks this afternoon and
early evening, and across parts of the central Gulf Coast states
late tonight into early Wednesday morning. Isolated strong storms
will also be possible today across part of north Florida and in the
vicinity of eastern Pennsylvania.

...FL...
A band of thunderstorms persists over northern FL, where a few
storms have shown considerable intensity this morning. While the
overall trends should be down through the early afternoon, isolated
wind damage may still occur in the strongest cells for a couple more
hours.

...OK/MO/KS/AR...
Water vapor loop shows an intense mid-level shortwave trough moving
across NM. This feature and an associated 80+ knot mid-level jet
max will rotate into TX, promoting a deepening surface low over
western/central OK. Strong southerly winds in the warm sector of
the developing cyclone will transport upper 50s dewpoints into much
of eastern OK by late afternoon, where 1000-1500 J/kg of MLCAPE will
reside. Present indications are that thunderstorms will form over
central OK in vicinity of the surface low and lift to the north of
the warm front. Vertical shear profiles will support supercell
structures capable of large hail, damaging winds, and perhaps a
tornado or two. 12Z CAM solutions suggest that an eventual
evolution into bowing structures is likely as storms track toward
southwest MO, suggesting a continued risk of hail and damaging
winds.

...PA/NY/NJ...
Visible satellite imagery suggests substantial cloud cover has
persisted over this region, with minimal destabilization so far
today. A few breaks in the clouds this afternoon moving in from the
west may coincide with the diurnal heating max, resulting in some
risk of a strong storm or two as the shortwave trough passes by.
Hail and/or gusty winds may occur in the strongest cells.

...LA/MS/AL/GA...
Few changes have been made to this forecast area. Strong low-level
warm/moist advection will develop late tonight over the central Gulf
Coast region, promoting scattered thunderstorm development. Much of
this activity will be elevated with hail being the main threat.
However, by 05/12Z, forecast soundings suggest some risk of damaging
winds or tornadoes along the retreating warm front. This risk will
evolve into a more robust severe weather event on Wednesday.
..Hart/Cohen.. 04/04/2017

A las 20:00z, se actualiza de vuelta.
----------------------------------------------
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 Abr 04, 2017 2:45 pm

Actualizacion del dia 2. Ampliaron un poco mas la zona bajo riesgo moderado por tiempo severo.
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Probabilidades de tiempo severo.
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Discusion.
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Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Tue Apr 04 2017

Valid 051200Z - 061200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
AL/GA/SC AND THE FL PANHANDLE...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OH/TN VALLEYS TO THE SOUTHEAST...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OH VALLEY
TO THE SOUTHEAST AND MID-ATLANTIC...

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

...SUMMARY...
An outbreak of severe thunderstorms is likely Wednesday across much
of the Southeast, continuing northward along and west of the
Appalachians into the Tennessee and Ohio Valleys. This will include
supercell development with a risk for tornadoes, some of which will
be strong and long-lived, particularly across the Southeast. Large
to very large hail and damaging straight-line winds also appear
likely.

...Synopsis...
A highly amplified mid/upper-level trough will be present across the
Plains at the beginning of the period, moving eastward to the MS
Valley by Wednesday evening, and continuing to the OH/TN Valleys and
Southeast by early Thursday morning. Two 100+ kt upper-level jets
will be present across areas of severe potential Wednesday, one
associated with the eastward-moving trough over LA/MS/AL/TN, and
another 90-100+ kt sub-tropical jet nosing over southeastern AL, the
FL Panhandle, and GA through Wednesday evening. Strong 50-80+ kt
mid-level southwesterly winds will overspread much of the OH/TN
Valleys and Southeast through the peak of the diurnal heating cycle,
and these winds will then overspread much of the East Coast
Wednesday evening through the end of the period.

A strong southwesterly low-level jet is expected to advect rich Gulf
moisture northward across portions of MS/AL/GA by Wednesday morning.
This jet will shift eastward across GA/SC/NC/VA through the
afternoon and early evening before strengthening further late
Wednesday into early Thursday morning across the Mid-Atlantic. A
somewhat separate corridor of strong southerly/southwesterly
low-level winds will be associated with the mid/upper-level trough,
and will overspread much of the OH/TN Valleys through the period. At
the surface, an area of low pressure initially over southeastern MO
will develop northeastward to IL/IN by Wednesday evening while
deepening. This low will then slowly continue northeastward to the
vicinity of the eastern Great Lakes by the end of the period. An
attendant cold front will move eastward across the OH/TN Valleys and
Southeast Wednesday, reaching the Mid-Atlantic by the end of the
period.

...Southeast into the Mid-Atlantic...
Warm air advection/LLJ related convection should form along the
northward-moving warm front early Wednesday morning across parts of
eastern MS, AL, and perhaps GA. This initial activity will pose a
threat for all severe hazards, including tornadoes along/south of
the front where surface-based convection will be more likely.
Additional supercell development appears likely within the broad
warm sector across the central Gulf Coast States, particularly
across AL into GA/SC Wednesday morning/afternoon as large-scale
ascent associated with the upper trough begins to overspread the
Southeast. Forecast soundings across this region suggest strong
tornadoes will be possible with any discrete storm that can form in
this environment, in addition to very large hail and damaging
straight-line winds. Severe probabilities have been
increased/expanded westward slightly in western AL/eastern MS with
latest model guidance showing convective development both Wednesday
morning and another round associated with the large-scale forcing
for ascent with the upper trough Wednesday afternoon ahead of the
cold front.

As the convection that develops Wednesday morning/afternoon moves
across the Carolinas in the evening, a nocturnal increase in
instability and resulting severe potential are possible across parts
of the Carolinas into southeastern VA. This would occur in tandem
with increasing low-level winds associated with a previously
mentioned low-level jet, and strengthening mid/upper-level winds
attendant to the approaching upper trough. If convection can become
surface based in this region, then all severe hazards may occur,
including a threat for tornadoes. Have accordingly
expanded/increased severe probabilities across the Carolinas and
southern/southeastern VA to account for this threat late Wednesday
night into early Thursday morning.

...OH/TN Valleys...
The northward advance of low-level moisture will be more limited
across the OH/TN Valleys Wednesday, but will still be more than
sufficient to support surface-based convection. A band of supercells
appear likely per latest model guidance given the strength of low
and mid-level winds coupled with weak to locally moderate
instability. Large to very large hail and damaging winds appear to
be the main threats, with a few tornadoes also possible. Given the
forecast coverage of convection, it is not out of the question that
higher severe probabilities may need to be considered in a later
outlook update.

..Gleason.. 04/04/2017

Se actualiza de vuelta a las 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 Abr 04, 2017 9:52 pm

Ultimas discusiones a mesoescala.
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Mesoscale Discussion 0428
NWS Storm Prediction Center Norman OK
0148 PM CDT Tue Apr 04 2017

Areas affected...Portions of central and eastern
Oklahoma...northwest Arkansas...far southwest Missouri...extreme
southeast Kansas

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

Valid 041848Z - 042115Z

Probability of Watch Issuance...95 percent

SUMMARY...The risk for severe thunderstorms will increase across
central Oklahoma around 20Z, and then develop eastward/northeastward
through the late afternoon and early evening. Large hail --
potentially significantly severe -- and locally damaging wind gusts
should be the primary hazards, though the possibility for a tornado
or two will exist in the vicinity of the Interstate 44 corridor from
the Norman/OKC area northeastward through the Tulsa area and into
far southwest Missouri.

DISCUSSION...Latest surface observations including the Oklahoma
Mesonet indicate a warm front extending from the Fort Smith AR area
arching westward to points near/south of Norman OK and then
extending southwestward to surface low pressure analyzed over
Tillman County OK. Surface convergence is increasing in proximity to
the low, with a pair of boundaries branching south of the low's
vicinity -- (1) a Pacific boundary arching southwestward into
southwest TX, and (2) a leading prefrontal trough arching into
central TX. Only partially modified Gulf moisture characterized by
surface dewpoints around 55-57F extends northward to and just north
of the aforementioned warm front. Diabatic heating of the modestly
moist boundary layer near and south of the warm front is
contributing to around 500 J/kg of MLCAPE per modifications to the
12Z Norman sounding, which indicated steep midlevel lapse rates of 8
C/km.

Meanwhile, in the midlevels, water vapor imagery depicts the leading
edge of a pronounced dry slot preceding a compact vorticity maximum
approaching far southwest OK. Related deep ascent and
destabilization aloft are encouraging swelling boundary-layer
cumulus fields near the surface low and immediately southward along
the Pacific boundary into western North Texas -- at the eastern
periphery of steepest low-level lapse rates (8.0-8.5 C/km in the
lowest 3 km above ground).

As the ascent continues to develop east-northeastward during the
next couple of hours, and diurnal heating continues to contribute to
erosion of MLCINH along the western edge of the return moisture,
storm development is forecast to occur near or to the west-southwest
of the OKC/Norman area around 20Z. This initial activity will likely
reside along the warm frontal zone -- perhaps immediately on the
cold side of the surface boundary amidst ongoing billow clouds. With
time, the warm front will continue developing northward across areas
from eastern OK to northwest AR and southwest MO, where 2-hour
pressure falls around 2-3 mb per 2 hours are ongoing. Thunderstorms
should subsequently spread east-northeastward and northeastward
through late afternoon/early evening, with additional preceding
storm development in proximity to the warm front and immediately on
its cool side in response to frontogenetic ascent.

Despite the overall dearth of moisture return and buoyancy, the
long/looping hodograph sampled by the TLX VAD wind profile near and
just to the north of the warm frontal zone where effective inflow
layers may extend to the surface, will support supercells capable of
potentially significant severe hail -- perhaps to baseball size.
Storm-scale upward accelerations will be bolstered by the steep
midlevel lapse rates, and upward perturbation pressure gradient
forces related to the long/looping hodograph structure, despite the
limited buoyancy. Locally damaging wind gusts may also occur with
any of the more pronounced bowing segments.

Furthermore, given the large effective SRH associated with the
aforementioned hodograph, storms residing near and just to the north
of the warm front could produce a tornado or two. However,
anticipated supercell motion may be oriented slightly to the cool
side of the surface boundary, which could eventually impede
low-level mesocyclone sustenance. Furthermore, the lack of richer
low-level moisture may also limit tornado potential. Regardless, the
Interstate 44 corridor from OKC/Norman northeastward through the
Tulsa area into into far southward MO could be a favored zone of
pre-existing warm-front-related vertical vorticity, enhanced
low-level SRH, and sufficient buoyancy for some tornado risk.

..Cohen/Darrow.. 04/04/2017

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Mesoscale Discussion 0429
NWS Storm Prediction Center Norman OK
0329 PM CDT Tue Apr 04 2017

Areas affected...Portions of the eastern FL Peninsula

Concerning...Severe potential...Watch unlikely

Valid 042029Z - 042230Z

Probability of Watch Issuance...5 percent

SUMMARY...Widely scattered strong to locally severe storms may
affect portions of the eastern FL Peninsula into the early evening.
Watch issuance is not necessary.

DISCUSSION...Widely scattered storms continue developing
eastward/southward along composite outflow and sea-breeze boundaries
into an uncapped environment characterized by around 1500-2000 J/kg
of MLCAPE. Relatively cold temperatures aloft supporting moderately
steep midlevel lapse rates (around 7.5 C/km at Miami at 12Z) will
enhance storm-scale updraft accelerations. Furthermore, 30-50 kt of
mid- and upper-tropospheric flow will offer sufficient deep shear
and convective ventilation for sustained convection and occasionally
organized convective structures. Recent radar trends suggest that
localized storm intensification is ongoing. With visible satellite
imagery indicating boundary-layer cumulus development in the buoyant
air mass to the south (serving as inflow to the aforementioned
activity) indicating the moist/unstable air mass, isolated severe
hail and wind potential may continue eastward/southward during the
next few hours.

..Cohen/Hart.. 04/04/2017

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Mesoscale Discussion 0430
NWS Storm Prediction Center Norman OK
0353 PM CDT Tue Apr 04 2017

Areas affected...Portions of central/eastern OK and north TX

Concerning...Severe Thunderstorm Watch 121...

Valid 042053Z - 042230Z

The severe weather threat for Severe Thunderstorm Watch 121
continues.

SUMMARY...Thunderstorm development is occurring across portions of
central OK, with storm intensification likely in the short term. The
severe risk continues in Watch 121. Isolated severe potential may
conditionally extend south of the Red River.

DISCUSSION...Thunderstorm development is occurring near/east of a
triple point near Norman Oklahoma. This activity will continue
developing eastward/northeastward and mature into organized
supercell structures capable of producing large hail -- some
significantly severe. Storms interacting with the warm frontal zone
from east of Lincoln County to near the Tulsa area and farther
northeast into far southwest MO should be the most intense, with the
risk of producing a tornado or two. Small bowing segments capable of
producing damaging wind gusts may also evolve. A storm evolving on
the warm side of the boundary in Seminole County is becoming
particularly intense, and may mature along the warm frontal zone as
it approaches locations near the Tulsa area. Storms well north of
the boundary will be capable of producing mainly severe hail.

Isolated thunderstorm potential may evolve from a swelling cumulus
field along a surface trough extending south of the triple point
into north Texas. North Texas may be a favored area for very
isolated storm development at the eastern edge of the
warmest/deepest boundary layer in the short term. However, capping
should restrict storm coverage, though isolated severe hail
potential could exist conditionally (watch issuance not presently
likely). However, isolated storms will likely develop southward
along the consolidating cold front in eastern Oklahoma later this
afternoon/evening.

..Cohen.. 04/04/2017

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Mesoscale Discussion 0431
NWS Storm Prediction Center Norman OK
0634 PM CDT Tue Apr 04 2017

Areas affected...Eastern Oklahoma...western Arkansas...southwestern
Missouri...and southeastern Kansas

Concerning...Severe Thunderstorm Watch 121...

Valid 042334Z - 050030Z

The severe weather threat for Severe Thunderstorm Watch 121
continues.

SUMMARY...The severe-weather threat continues across portions of WW
121. Local extensions of this watch in time and space may be needed
especially across southwestern Missouri beyond the scheduled 02Z
expiration time of WW 121.

DISCUSSION...Scattered hail-producing thunderstorms continue to move
northeastward across the WW at this time. The greatest severe
threat currently exists within a complex in far northeastern
Oklahoma that earlier produced widespread 1-2 inch diameter hail
stones near the Tulsa metro area. These storms will soon cross into
Missouri, with a continued hail and isolated wind threat as storms
potentially congeal into linear segments. A tornado cannot be ruled
out through dark. It is uncertain how far northeast into Missouri
the severe threat will exist owing to weaker surface-based
instability northeast of Springfield. Most of the severe weather
threat is expected to diminish after 02Z, although local space/time
extensions of WW 121 may be needed thereafter to address any
lingering severe threat.

Farther south along a dryline near the US 69 corridor, scattered
thunderstorms have increased over the past 1-2 hours, with some
supercell structures noted. Hail and wind gusts will be the primary
threat with this relatively high-based activity resulting from
strong shear and steep mid-level lapse rates, but modest low-level
moisture content. An isolated severe threat may extend into western
Arkansas with this activity - especially if ongoing dryline storms
can congeal into a line.

Finally, areas on the northwestern periphery of WW 121 may
experience isolated instances of one-inch hail as elevated storms
move northeastward through this region.

..Cook/Edwards.. 04/04/2017

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Mesoscale Discussion 0432
NWS Storm Prediction Center Norman OK
0637 PM CDT Tue Apr 04 2017

Areas affected...North-central/northeast TX to far southwest AR/far
northwest LA

Concerning...Severe potential...Watch unlikely

Valid 042337Z - 050130Z

Probability of Watch Issuance...20 percent

SUMMARY...At isolated severe risk, mostly in the form of hail, may
develop through the early/mid-evening hours across parts of
north-central TX to far southwest AR/far northwest LA. The overall
coverage/magnitude of the severe risk should preclude a watch
issuance.

DISCUSSION...Visible satellite imagery continues to show a gradual
deepening of boundary-layer cumulus near a dryline as it extends
from just east of Durant OK south-southwestward to northern/western
portions of the DFW Metroplex as of 23Z/6pm CDT. While the boundary
layer is not overly moist with surface dewpoints in the 50s F, steep
low/mid-level lapse rates likely support a near-dryline corridor of
MLCAPE around 1000 J/kg. While the the southward extent of sustained
deep-convective development across north-central/northeast TX is not
certain this evening, additional DPVA-related forcing for ascent
will overspread the area and the upstream front will eventually
overtake the dryline across north TX. If/where storms develop and
remain sustained this evening, sufficient buoyancy and ample
effective shear (40+ kt) would support an isolated severe risk this
evening, mainly in the form of hail.

..Guyer/Edwards.. 04/04/2017

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Mesoscale Discussion 0433
NWS Storm Prediction Center Norman OK
0740 PM CDT Tue Apr 04 2017

Areas affected...Southwest MO

Concerning...Severe Thunderstorm Watch 121...

Valid 050040Z - 050145Z

The severe weather threat for Severe Thunderstorm Watch 121
continues.

SUMMARY...A semi-focused damaging wind/some tornado risk should
continue to develop northeastward through 01Z-02Z (8-9pm CDT) across
southwest MO, including the I-44 corridor from near the Mount Vernon
area northeastward toward the Springfield metro. A spatial extension
of the existing watch will be necessary.

DISCUSSION...A strong supercell with a history of probable tornado
damage near Goodman MO continues to steadily progress northeastward
across southwest MO, approaching I-44 and the Mount Vernon MO
vicinity as of 730 pm CDT. While the background environment is not
overly moist or unstable amidst only lower 50s F surface dewpoints,
adequate low-level moisture/buoyancy exists coincident with a
corridor of strong low-level shear and 3+ mb/2-hour pressure falls
near a warm front as it parallels I-44 through the Springfield area.
While the the longevity of a semi-discrete-supercell-related tornado
risk is not certain, an impactful severe risk (damaging winds at the
very least) should continue to favor the warm front including areas
near/south of I-44 and the Springfield metro through mid-evening.

..Guyer.. 04/05/2017

-------------------------------------------------
Watches.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 121
NWS Storm Prediction Center Norman OK
230 PM CDT Tue Apr 4 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Northwest Arkansas
Southeast Kansas
Southwest Missouri
Central and Northeast Oklahoma

* Effective this Tuesday afternoon and evening from 230 PM until
900 PM CDT.

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

SUMMARY...Scattered severe thunderstorms are expected to develop
over central Oklahoma by 4pm. This activity will spread/develop
northeast into portions of southeast Kansas and southwest Missouri
and northwest Arkansas. Large hail and damaging winds are the
primary threats, though a tornado or two could be noted with the
strongest activity near the I-44 corridor.

The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 5 miles southwest of
Oklahoma City OK to 15 miles east of Monett MO. 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
3 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
21030.

...Darrow

1 solo tornado fue reportado en el limite entre Oklahoma, Missouri y Arkansas. 17 reportes de viento y 45 de granizo. En total, son 63.
Dome, dome, dome..The life is a dome

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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mié Abr 05, 2017 7:57 am

Muy interesante el dia que se viene.
Imagen
% de tornados.
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% de vientos.
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% de granizo.
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Imagen

Discusion:
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Wed Apr 05 2017

Valid 051200Z - 061200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
KENTUCKY INTO MIDDLE TENNESSEE...ALABAMA...GEORGIA AND WESTERN SOUTH
CAROLINA...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
VALLEY INTO THE SOUTHEAST STATES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OH VALLEY
INTO THE SOUTHEAST STATES AND MID ATLANTIC...

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

...SUMMARY...
An outbreak of severe thunderstorms is likely Wednesday across much
of the Southeast, continuing northward along and west of the
Appalachians into the Tennessee and Ohio Valleys. This will include
supercell development with a risk for tornadoes, some of which will
be strong and long-lived, particularly across the Southeast. Large
to very large hail and damaging straight-line winds also appear
likely.

...Synopsis...

Vigorous upper trough will continue east into the OH and TN Valleys
and southeast states today. Initial vorticity maximum embedded
within this feature will pivot northeast into the western parts of
the OH valley by midday with associated surface low consolidating
over IL and deepening as it develops farther east during the
afternoon. A secondary vorticity maximum accompanied by a strong
upper jet will rotate through the base of the trough and into the
southeast states this afternoon. At the surface a cold front should
extend from the surface low in mo southward into LA at the start of
the period, while a warm front will extend from southern GA through
southern AL and MS. The warm front should advance north, likely
reaching central GA into central AL by midday while the cold front
will continue east and reach the Atlantic seaboard by the end of
this period.

...Southeast States...

A very moist warm sector with low 70s F dewpoints will reside south
of northward-advancing warm front across the Gulf Coast states with
dewpoints generally in the 70s. North of this boundary, slightly
elevated storms will likely be ongoing from southern and central MS
through central AL and central to northern GA. Large hail will be
the primary threat with the early storms. However, any storms
developing near the warm front or in the warm sector will be surface
based and pose a threat for tornadoes given favorable low-level
hodographs. As the boundary layer warms additional storms will
likely develop in the warm sector where strong (50+ Kt) effective
bulk shear will support supercells with an attendant threat for very
large hail and tornadoes. Tendency will be for low-level winds to
veer with time over MS and central and southern AL in wake of a
disturbance embedded the subtropical jet. This suggests the greater
tornado threat may be during the morning into early afternoon in
these areas. Tornado threat is expected to be more persistent
farther east across GA warm sector and especially near the warm
front with storms on the southern flank of the MCS where
near-surface winds will remain backed to southerly into the
afternoon supporting large 0-1 km hodographs as the low-level jet
gradually develops east. Given the favorable kinematic environment,
very large hail and a few strong tornadoes are possible during the
day as the boundary layer moistens and destabilizes along and south
of the warm front. The threat should shift east into SC by late
afternoon into the evening. Additional storms that develop along the
cold front farther west could move into this region during the late
afternoon and evening posing an additional severe threat.

...Tennessee through Ohio Valley...

A relatively narrow corridor of dewpoints in the upper 50s near 60 F
will advect north into the TN Valley in advance of the approaching
cold front and vigorous shortwave trough contributing to moderate
instability (1500 J/kg MLCAPE) as the boundary layer warms during
the afternoon. A secondary branch of the low-level jet will
strengthen within exit region of approaching mid-level jet, and
storms are expected to develop along and just ahead of the front by
mid afternoon from the OH valley southward into the middle part of
the TN valley. Discrete supercells will likely be the initial mode,
and these storms will be capable of producing very large hail and
tornadoes as they develop east and mature. An eventual upscale
growth into mixed modes with line segments may occur during the
evening as activity approaches the Appalachians.

...Mid Atlantic area...

Given the expected widespread convection in vicinity of the warm
front expanding east through the Carolinas during the day, the
degree of northward destabilization into the middle Atlantic area
remains uncertain. Nevertheless, severe threat will likely undergo
some increase late in the period as forcing for ascent and vertical
shear increase amidst a marginally unstable environment.

..Dial/Cook.. 04/05/2017

Se actualiza a las 13:00z.
-----------------------------------------------------
Primera discusion a mesoescala del dia.
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Mesoscale Discussion 0437
NWS Storm Prediction Center Norman OK
0341 AM CDT Wed Apr 05 2017

Areas affected...far eastern Mississippi/southern and central
Alabama/western and central Georgia/parts of the Florida Panhandle

Concerning...Severe Thunderstorm Watch 123...

Valid 050841Z - 051045Z

The severe weather threat for Severe Thunderstorm Watch 123
continues.

SUMMARY...Scattered strong/locally severe storms continue spreading
northeast across the southern Alabama/southwest Georgia vicinity,
where local severe risk -- mainly in the form of large hail -- is
ongoing. A continued/gradual increase in both storm coverage and
severe risk is expected over the next several hours.

DISCUSSION...Latest radar loop shows scattered strong -- and
primarily elevated -- storms across the southern AL/southwest GA
vicinity. One earlier cell -- over the FL panhandle -- was able to
briefly become a near surface-based right-moving supercell, but has
since weakened to below severe levels. Meanwhile, the left-moving
storms ongoing farther north are aligned roughly along the
developing warm front -- which is demarcating the leading edge of a
surge of low to mid 70s dewpoint Gulf air. In the short term, the
main severe risk will remain associated with these initial/slightly
elevated storms -- primarily in the form of large hail.

With time, surface-based storms are expected to evolve -- both along
the southern fringe of the ongoing band of convection as well as
evolving from within streets of showers now becoming evident within
the higher-dewpoint boundary layer near the Gulf coast. This
surface-based convective evolution will pose an increasing
surface-based threat though timing remains a bit uncertain at this
point. We will continue to monitor environmental evolution and
convective trends, with an eye toward later -- likely tornado --
watch issuance.

..Goss.. 04/05/2017

---------------------------------------
Primer watch del dia.
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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 123
NWS Storm Prediction Center Norman OK
135 AM CDT Wed Apr 5 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Southeast Alabama
A small part of the Florida Panhandle
Southwest Georgia

* Effective this Wednesday morning from 135 AM until 800 AM CDT.

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

SUMMARY...Thunderstorms will continue to spread northeastward
through the early morning hours across southeast Alabama and
southwest Georgia. The storm environment will favor slightly
elevated supercells with large hail on the leading edge of the area
of convection. A couple of surface-based supercells will be
possible on the southern fringe of the larger convective cluster,
where an isolated tornado or two could occur later this morning.

The severe thunderstorm watch area is approximately along and 70
statute miles north and south of a line from 25 miles south of Selma
AL to 35 miles north of Albany GA. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

OTHER WATCH INFORMATION...CONTINUE...WW 122...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
24030.

...Thompson
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mié Abr 05, 2017 9:28 am

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Mesoscale Discussion 0438
NWS Storm Prediction Center Norman OK
0615 AM CDT Wed Apr 05 2017

Areas affected...Alabama/western Georgia and into the Florida
Panhandle

Concerning...Severe Thunderstorm Watch 123...

Valid 051115Z - 051245Z

The severe weather threat for Severe Thunderstorm Watch 123
continues.

SUMMARY...Strong/locally severe storms continue across much of
Alabama and into western Georgia and vicinity at this time. Hail,
and perhaps locally damaging winds, remain the primary risk in the
short term, though wind and tornado risk will gradually increase
this morning (eventually requiring tornado watch issuance).

DISCUSSION...Latest radar loop shows scattered strong/locally severe
storms ongoing across WW 123 at this time, with the strongest storms
existing within a cluster east of Birmingham moving eastward toward
northwest Georgia. These storms are ongoing along the leading edge
of the low-level moisture return and likely remain slightly elevated
-- with large hail the primary risk along with the possibility of a
few stronger gusts.

Meanwhile, south and west of the stronger convection, isolated
showers/thunderstorms continue to increase, ahead of the advancing
upper system and associated cold front where an increasingly
moist/unstable airmass resides. As this trend continues, eventual
development of surface-based supercells is expected; given the
scheduled 13z expiration of WW 123, a new (likely to be) tornado
watch will be required.

..Goss.. 04/05/2017

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URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 124
NWS Storm Prediction Center Norman OK
650 AM CDT Wed Apr 5 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
much of Alabama
western portions of the Florida Panhandle
western Georgia
parts of eastern Mississippi
Coastal Waters

* Effective this Wednesday morning from 650 AM until NOON CDT.

* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
Scattered damaging wind gusts to 65 mph possible

SUMMARY...An increase in storm coverage and intensity is expected
this morning, with several supercell storms expected to evolve
through midday. Potential for very large hail and locally damaging
winds is evident -- along with a few tornadoes.

The tornado watch area is approximately along and 100 statute miles
north and south of a line from 80 miles north northwest of Mobile AL
to 15 miles northeast of Macon GA. 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 123...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean
storm motion vector 24035.

...Goss
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mié Abr 05, 2017 10:35 am

Les dejo la reciente actualizacion del convective outlook para el dia de hoy. No hay grandes cambios.
Imagen
% de tornados.
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Vientos de hasta 50kt.
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Imagen

Granizo.
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Imagen

Hasta ahora, los riesgos mas significativos, serian los granizos y tornados.
Discusion.
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Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0744 AM CDT Wed Apr 05 2017

Valid 051300Z - 061200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THROUGH LATE
EVENING FROM EASTERN ALABAMA ACROSS MUCH OF GEORGIA TO WEST CENTRAL
SOUTH CAROLINA...AND NORTHWARD ACROSS EASTERN TENNESSEE TO SOUTH
CENTRAL KENTUCKY...

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
MODERATE RISK AREA...FROM THE OHIO VALLEY TO THE CAROLINAS AND
NORTHEAST GULF COAST...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED RISK AREA...

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

...SUMMARY...
An outbreak of severe thunderstorms with a few strong tornadoes,
very large hail, and damaging winds is expected today into tonight
from Alabama and Georgia into South Carolina, as well as northward
into middle and eastern Tennessee and central Kentucky.

...An outbreak of severe thunderstorms expected today into
tonight...

...Synopsis...
A surface cyclone in south central MO this morning will develop
east-northeastward to southern IN by this evening and northern OH by
06/12z, in advance of an amplifying midlevel trough now over the
Ozarks. An embedded shortwave trough/jet streak will rotate around
the southern periphery of the midlevel trough, from northwest TX
this morning to the lower MS Valley this evening and the southern
Appalachians overnight, which will eventually foster secondary
cyclogenesis in VA. A trailing surface cold front will likewise
progress eastward to middle TN and central AL by late evening, and
continue eastward to the Piedmont and northeast Gulf coast by the
end of the period. In advance of the cold front, a maritime
tropical air mass is spreading northward across MS/AL/GA, which will
contribute to substantial destabilization and relatively widespread
severe thunderstorm development today into tonight across the
Southeast, and this afternoon/evening into the OH Valley.

...MS/AL/GA/Carolinas through tonight...
Elevated thunderstorms have been ongoing much of the night and
continue to spread east-northeastward across central AL/GA in a
warm-advection regime on the edge of the returning tropical
moisture. Embedded supercells are expected to persist into the day,
with an increasing risk for surface-based supercell development on
the southern fringe of the ongoing cluster as the low levels
destabilize with surface heating, as well as in the open warm sector
in central/southern AL. The combination of moderate-strong buoyancy
(MLCAPE 2000-3000 J/kg), effective bulk shear of 55-70 kt will
support multiple supercells capable of producing isolated very large
hail and damaging winds. Long, straight hodographs will
characterize the wind profiles, with only modest low-level hodograph
curvature expected along a branch of the 40-50 kt southwesterly
low-level jet across GA. Still, the strong buoyancy and effective
SRH in excess of 200 m2/s2 will be sufficient for the risk of a few
strong tornadoes mainly across eastern AL, GA and west central SC
through the afternoon/evening.

Tonight, the southern extent of the cold-frontal severe storms will
move eastward from AL into GA, potentially moving along the same
corridor affecting by storms during the day. Some form of this
convection will move across GA/SC and possibly into NC overnight,
with all severe hazards possible.

...OH/TN Valleys this afternoon/evening...
An increase in low-level moisture will occur today from TN northward
to the lower OH Valley, in advance of the surface cyclone/cold front
and west of the ongoing convection across AL/GA. Some surface
heating will occur ahead of the front per morning satellite imagery,
which combined with the moistening, will result in a corridor of
moderate buoyancy extending northward from northern AL across middle
TN into central KY, and perhaps southern IN. Convective initiation
is expected along or just ahead of the front by mid afternoon, with
sufficient cross-boundary flow/shear for discrete storms to move off
the boundary. Deep-layer vertical shear and buoyancy will favor
supercells capable of producing large hail and damaging winds, while
a branch of the low-level jet across TN/KY will provide sufficient
low-level shear for isolated strong tornadoes from about 21-02z.

..Thompson/Cohen.. 04/05/2017

A las 16:30z, lo van a volver a actualizar.
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mié Abr 05, 2017 12:08 pm

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Mesoscale Discussion 0439
NWS Storm Prediction Center Norman OK
0925 AM CDT Wed Apr 05 2017

Areas affected...Northeast AL...Northern GA...SC

Concerning...Severe potential...Watch possible

Valid 051425Z - 051600Z

Probability of Watch Issuance...40 percent

SUMMARY...Clusters of severe thunderstorms should focus along a
corridor from northeast AL into central SC over the next 2-4 hours.
New WW may be required downstream across SC to account for an
expanding severe threat.

DISCUSSION...Latest radar trends support a broad sustained corridor
of low-level warm advection-induced thunderstorms from northeast AL
across northern GA. With LLJ expected to strengthen across GA, as
the day progresses, it appears moistening/forcing for ascent will
increase the likelihood for clusters of severe thunderstorms to
spread/develop into SC. Increasing buoyancy amidst strengthening
shear aids confidence in a multifaceted severe event across this
region. Supercells are likely within this environment along with
bow-type structures. Large hail, damaging winds, and tornadoes are
possible.

..Darrow/Hart.. 04/05/2017

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Mesoscale Discussion 0440
NWS Storm Prediction Center Norman OK
0943 AM CDT Wed Apr 05 2017

Areas affected...Portions of AL/GA/SC

Concerning...Outlook upgrade

Valid 051443Z - 051645Z

SUMMARY...Portions of the states of AL/GA/SC are being considered
for an Outlook upgrade -- though the details are still being
analyzed. A very notable dry bias is apparent in the latest model
guidance, and observational data and previous model runs are being
heavily referenced in Outlook preparation.

DISCUSSION...GPS PW data are exhibiting a low bias by at least 0.5
inch from parts of AL into GA, which has influenced initialization
of the latest numerical weather prediction guidance. Per
coordination with the Weather Prediction Center, it appears that
related initialization is causing substantial dry biases in model
guidance -- extended through the Day 1 forecast period. With an
inland influx of rich moisture feeding ongoing intense supercells in
southern AL (with dewpoints into the middle 70s), and the
around-16.6-g/kg mean mixing ratio per LIX 12Z sounding, and around
1.5-inch PW per Atlanta and Birmingham 12Z soundings, it is evident
that rich moisture and related strong buoyancy does indeed extend
inland. As such, observational data and previous model runs will
play a major role in the consideration for a High Risk upgrade, as
the dry bias has influenced the latest model guidance. While an
Outlook upgrade is possible, it is not certain.

..Cohen/Marsh/Hart.. 04/05/2017
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Re: Seguimiento general en EEUU

Mensajepor stormchaserAlberto » Mié Abr 05, 2017 12:47 pm

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Mesoscale Discussion 0441
NWS Storm Prediction Center Norman OK
1038 AM CDT Wed Apr 05 2017

Areas affected...FL Panhandle...GA...Southwest SC

Concerning...Severe potential...Watch likely

Valid 051538Z - 051715Z

Probability of Watch Issuance...95 percent

SUMMARY...Tornado Watch will be issued by 17z to address increasing
severe threat from the eastern FL Panhandle into SC.

DISCUSSION...Boundary-layer cu field is beginning to deepen from the
eastern FL Panhandle into southeast GA as surface temperatures rise
to near 80F. Latest high-res Vis imagery depicts
clustering/towering CU along a corridor from near MAI to near VDI.
Substantial breaks in cloud cover suggest additional heating can be
expected and thunderstorms will likely evolve over the next few
hours. Given the strength of the wind fields and rising instability
there is increasing concern for discrete supercell formation by
early afternoon. Environmental parameters appear favorable for a
few strong tornadoes across this region, in addition to large hail
and damaging winds. Tornado watch will be issued for parts of this
area by 17z.

..Darrow/Hart.. 04/05/2017
Dome, dome, dome..The life is a dome

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Seba
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Re: Seguimiento general en EEUU

Mensajepor Seba » Mié Abr 05, 2017 3:44 pm

Hay riesgo ALTO para hoy en el SE de USA y lanzaron un PDS.
Picantisimo.
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Ezequiel95
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Re: Seguimiento general en EEUU

Mensajepor Ezequiel95 » Mié Abr 05, 2017 4:17 pm

Tienen tiempo severo casi todos los dias... Que lindo


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