U.S. Severe Weather Forecast (Convective Outlook)

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Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1131 PM CST Sat Feb 24 2018 


Valid 251200z - 261200z 


..there is a marginal risk of severe thunderstorms across parts of 
the central Gulf Coast Sunday night... 


... 
General thunderstorms are expected mainly from Texas eastward along 
the central Gulf Coast on Sunday. A few storms may be capable of 
localized wind damage or a brief/weak tornado, mainly across 
southern Louisiana into the far western Florida Panhandle overnight. 


... 
An intense, negatively tilted shortwave trough will move from the 
Midwest across the Great Lakes during the day, with strong 
southwesterly flow aloft remaining over much of the eastern half of 
the Continental U.S.. a secondary, lower-amplitude wave will move from The Four 
Corners to the plains during the day, and across the Ohio Valley 
overnight. At the surface, low pressure will continue northward from 
Lake Superior across Ontario. An occluding front will extend south 
into New York and PA, with a cold front roughly from the Appalachians to 
the central Gulf and southeast Texas during the afternoon. 


Upper 60s f dewpoints will exist ahead of the Gulf of Mexico portion 
of the front, which will continue a southward drift for much of the 
day. As the secondary wave moves into the plains, southerly 
low-level flow will increase, allowing for warm/moist advection and 
a retreat of the front from southern la into the western Florida 
Panhandle. 


Elsewhere, showers and perhaps a few weak thunderstorms are expected 
across Alabama into Georgia during the day, but there will be little to 
support severe or organized storms. 


..central Gulf Coast region... 
While a few showers and storms are expected along the 
southward-moving cold front early in the day, these are not expected 
to be severe. Additional elevated showers and storms are expected 
over much of eastern Texas into central la, perhaps producing small 
hail at best. Overnight, southerly 850 mb flow should increase to 
around 30 kt, resulting in lift and a slow northward shift of the 
boundary. Up to 1000 j/kg MUCAPE is forecast to move into la, with 
up to 500 j/kg farther east along the coast. Most of the lift will 
be north of the front, but the very moist air mass should allow for 
surface based storms. Sufficient low-level shear supportive of 
modest rotation will exist, and a brief/weak tornado or strong wind 
gust cannot be ruled out. 


.Jewell/leitman.. 02/25/2018 


$$ 

Mesoscale Discussion


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Mesoscale discussion 0097 
National Weather Service Storm Prediction Center Norman OK 
0959 PM CST Sat Feb 24 2018 


Areas affected...middle Tennessee...eastern Kentucky and parts of 
adjacent southern Ohio and West Virginia 


Concerning...Tornado Watch 6... 


Valid 250359z - 250530z 


The severe weather threat for Tornado Watch 6 continues. 


Summary...a risk for severe weather continues, but this threat is in 
the process of becoming increasingly marginal, and a new watch is 
not anticipated. 


Discussion...overall, even the most vigorous convection is becoming 
generally low-topped as associated large-scale forcing for ascent 
spreads toward the upper Ohio Valley/central Appalachians. 
Lightning has diminished considerably further in the past couple of 
hours, and these trends seem likely to continue into and through the 
1-4 am EST time frame. Although the surface warm front has advanced 
into the vicinity of the Ohio River, the boundary layer ahead of the 
convective line becomes progressively cooler and drier eastward into 
the Cumberland Plateau. Further potential for tornadoes seems 
rather limited, but downward mixing of stronger momentum could 
continue to contribute to sporadic damaging wind gusts at least 
another couple of hours. 


.Kerr.. 02/25/2018 


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


Attention...WFO...rlx...mrx...jkl...iln...lmk...ohx...hun... 


Latitude...Lon 38338497 38958414 39158314 38588214 37398295 36018475 
35388588 35308650 35768705 37038585 37878545 38338497