U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 180709 
Storm Prediction Center ac 180708 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0208 am CDT Wed Sep 18 2019 

Valid 201200z - 211200z 

..there is a slight risk of severe thunderstorms over the northern 

Scattered severe storms are possible on Friday across the northern 
plains, with isolated activity into the Central High plains. 

An upper trough will move across The Rockies and into the plains, 
with an upper low deepening over Montana. Modest south/southwest winds 
aloft will exist during the day over the plains before a 
strengthening wave pivots northeast out of Wyoming and Colorado overnight. Low 
pressure will develop over the northern High Plains during the day, 
shifting into Canada overnight. Southerly winds across the plains 
will maintain 60s f dewpoints with areas of moderate instability 
supporting strong to severe storms ahead of a cold front that will 
sweep east across the Dakotas and Nebraska late. 

..northern plains... 
A few storms may be ongoing Friday morning over ND in a warm 
advection regime with hail possible. Continued height falls aloft as 
well as a warming boundary layer will lead to an uncapped air mass 
extending south along the surface trough/wind shift, with additional 
scattered storms expected by 21z from the central Dakotas into 
western NE. Subtle hodograph details/weaknesses aside, generally 
veering and increasing winds with height combined with the strong 
instability will generally support severe hail, wind, and perhaps a 
couple tornadoes. Given the meridional winds aloft and front 
orientation, storm Mode may become complex with merging cells as the 
corridor of storms gradually translates east, possibly reaching 
western Minnesota by Saturday morning. 

To the South, Strong heating and sufficient convergence near the 
surface trough may lead to isolated late-afternoon storms over 
eastern Colorado and western Kansas. Ample deep-layer shear as well as 30+ kt 
south/southeast winds at 850 mb will conditionally support a 
supercell or two capable of large hail and perhaps a brief tornado. 
At this time, storm coverage is uncertain but a slight risk may be 
needed for parts of the Central High plains in later outlooks should 
expected coverage increase. 

.Jewell.. 09/18/2019