U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 251245 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0645 am CST sun Feb 25 2018 


Valid 251300z - 261200z 


..there is a marginal risk of severe thunderstorms from the Texas 
Hill country east to the central Gulf Coast region... 


... 
Thunderstorms are expected mainly from Texas eastward along the 
central Gulf Coast to the Carolinas on Sunday. A few storms may be 
capable of producing hail, localized wind damage or a brief/weak 
tornado, mainly across southeast Texas and The Hill Country today, 
and then across southern Louisiana into the far western Florida 
Panhandle overnight. 


... 
As short-wave upper-level troughing sweeps across the upper Great 
Lakes region and curls across Ontario/Quebec with time, a second 
trough crossing The Four Corners area at this time will advance east 
across the plains today. 


At the surface, a cold front will continue to advance across the 
eastern states today, and shift into the western Atlantic with time. 
Meanwhile, this front will elongate west-to-east and stall across 
the Gulf coastal area today and tonight. 


..the Texas Hill country eastward across the central Gulf Coast 
region... 
scattered showers and thunderstorms are ongoing across the Texas 
Hill country and into southeast Texas this morning -- with one 
persistent/elevated supercell just south of San Antonio shifting 
east with time. This storm should remain elevated just to the north 
of the surface front, though orientation of the front relative to 
the storm's motion suggests some risk that this cell becomes a bit 
more surface-based and possibly interacts with the boundary as it 
nears the middle Texas coast. In addition to hail risk, a very 
low-end/conditional wind/brief tornado risk could evolve if the 
storm indeed becomes more surface-based. Otherwise, marginal hail 
with elevated convection will remain the primary -- albeit low-end 
-- risk as a zone of qg ascent spreads east into the Gulf Coast 
states this afternoon and evening. 


Later tonight, as this zone of ascent -- comprised of a weak 
disturbance in the sub-tropical jet and associated low-level jet -- 
crosses Louisiana, models hint that weak frontal wave development 
may occur. This could allow the remnant/lingering cold front to 
lift north slightly as a warm front ahead of the weak low. Within 
this potential/small warm sector, some potential for a stronger wind 
gust or brief tornado could evolve. Otherwise, marginal hail north 
of the low/front should be the extent of any severe risk through the 
end of the period. 


.Goss/marsh.. 02/25/2018 


$$ 

Mesoscale Discussion


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Storm Prediction Center mesoscale discussion 250600 
laz000-txz000-250730- 


Mesoscale discussion 0098 
National Weather Service Storm Prediction Center Norman OK 
1200 am CST sun Feb 25 2018 


Areas affected...Texas coastal plain 


Concerning...severe potential...watch unlikely 


Valid 250600z - 250730z 


Probability of watch issuance...5 percent 


Summary...some thunderstorm activity developing across the region 
could become fairly strong through the 2-4 am CST time frame. 
Overall, though, the severe weather potential seems limited, and a 
watch is not currently anticipated. 


Discussion...scattered thunderstorm development is underway near and 
ahead of the weak surface front advancing into the Texas coastal 
plain. This is being aided by forcing for ascent associated with 
another low-amplitude short wave impulse crossing the lower Rio 
Grande Valley, within the subtropical westerlies. Although 
southerly low-level flow across the region is generally modest, with 
speeds up to 30 kt generally confined to Upper Texas coastal areas, 
deep layer shear is strong. With layers of modestly steep lower/mid 
tropospheric lapse rates contributing to cape up to around 1000 j/kg 
(for moist boundary layer parcels with dew points in the upper 60s 
to near 70), some of these storms could be accompanied by some risk 
for severe hail into the 07-09z time frame. Eventually, upscale 
convective growth is possible along and just ahead of the front. As 
this occurs, the risk for hail probably will decrease, but a few 
locally strong wind gusts may accompany developing outflow. 


.Kerr/grams.. 02/25/2018 


..please see www.Spc.NOAA.Gov for graphic product... 


Attention...WFO...lch...hgx...crp...ewx... 


Latitude...Lon 29389792 29819689 30329548 30699453 30749369 29739370 
29199540 28219685 28179780 29389792