U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 210707 
Storm Prediction Center ac 210706 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0206 am CDT Mon may 21 2018 

Valid 231200z - 241200z 

..there is a marginal risk of severe thunderstorms across the 
plains and middle Atlantic... 

Isolated severe thunderstorms are possible across much of the plains 
while strong storms may develop across Virginia/North Carolina. 


Remnants of an upper low over Southern California will eject across the 
Great Basin into Montana during the day3 period as a corridor of somewhat 
stronger mid-level flow translates across eastern Wyoming into the Black 
Hills region. Even so, this belt of stronger flow will only be on 
the order of 30-40kt at 500mb, but more than adequate for sustaining 
organized updrafts along western plume of moisture/instability. One 
negative for widespread convection across the northern High Plains 
region will be the neutral/weak height rises despite the presence of 
the aforementioned short wave. Latest thinking is strong 
boundary-layer heating and orographic influences will contribute to 
convective development, some of which will likely be robust in 
nature. Low-level warm advection will likely induce strong 
convection across the Dakotas as low level jet is expected to veer into 
southeast South Dakota during the latter half of the period. 


Northwesterly flow will deepen across the middle Atlantic/southeast 
into the day3 period as a strong short-wave trough digs across 
northern New England. This northwesterly flow will encourage a 
surface front to surge into Virginia early in the period before moving off 
the Carolina coast during the overnight hours. Strong heating ahead 
of this boundary, along with modest mid-level flow, suggest any 
storms that form along the front could produce gusty winds/hail. 

.Darrow.. 05/21/2018