U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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Storm Prediction Center ac 210715 


Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0215 am CDT Wed Aug 21 2019 


Valid 231200z - 241200z 


..there is a marginal risk of severe thunderstorms from North 
Carolina into southern Virginia... 


... 
Isolated severe wind gusts are possible Friday over parts of North 
Carolina and southern Virginia. 


... 
An upper low will pivot northeast across the Canadian Maritimes, 
with a jet streak sweeping across New England and tail end near the 
mid Atlantic. At the surface, high pressure will remain over the 
Great Lakes, with a cold front moving south toward the Virginia/NC border. 
A weak surface low is forecast to develop over eastern Virginia and NC 
near the front where 70s f dewpoints and heating will contribute to 
moderate destabilization. 


To the west, a leading shortwave trough will eject out of the 
Dakotas toward western Ontario as a broad upper jet noses into the 
northern High Plains Friday night. Dewpoints in the 60s f will exist 
over the Dakotas ahead of a dying front related to the leading wave, 
and will back westward toward Montana by 12z Saturday. 


Elsewhere, a loose east-west boundary will remain roughly from Kentucky/Tennessee 
into north TX, with bouts of mainly non-severe thunderstorms through 
the period. 


..NC into southern Virginia... 
Strong heating of a moist air mass will occur south of the cold 
front approaching the Virginia/NC border late in the day. Forecast 
soundings indicate 2000-2500 j/kg MLCAPE developing despite poor 
midlevel lapse rates, though low-level lapse rates will become 
steep. With no capping present, the front will provide a focus for 
scattered storms, which may produce locally severe wind gusts as 
they propagate southeastward from Virginia into NC. Models are in good 
agreement depicting a relatively concentrated area of storms in this 
area. 


..northern High Plains... 
Elevated thunderstorms may be ongoing Friday morning over central ND 
in association with the departing shortwave trough, but will likely 
lose strength as lift wanes, and due to dry trajectories out of the 
surface high to the east. As cooling aloft arrives from the west, 
lapse rates as well as deep shear will increase, conditionally 
favoring elevated hail into Saturday morning over eastern Montana. At 
this time, storm chances prior to 12z Saturday appear too low to 
introduce severe probabilities. 


.Jewell.. 08/21/2019 


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