U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 290517 
Storm Prediction Center ac 290516 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1216 am CDT Friday Jul 29 2016 

Valid 311200z - 011200z 

..there is a marginal risk of severe thunderstorms across the northern plains... 

scattered thunderstorms...some severe...are expected to develop 
during the late afternoon across the western Dakotas...spreading 
into the eastern Dakotas after dark. 


Strong middle-level short-wave trough is forecast to eject inland 
across British Columbia into sk by the end of the period. Southern influence of this 
feature will affect the northern plains late as 500mb speed maximum...near 
50kt...translates east along the international border. Associated 
surface front will surge across Montana into western ND by late afternoon and 
strong boundary-layer heating should remove convective inhibition. 
As temperatures warm through the middle 90s scattered thunderstorms should evolve 
along the front. This activity will form within a sheared 
environment favorable for rotating updrafts and a few supercells 
could be noted. Low level jet is forecast to increase across the northern plains 
late and this should encourage clustering and perhaps an mesoscale convective system will 
evolve after dark within favored warm advection regime. 


Poor middle-level lapse rates will affect much of the 
country...especially the eastern Continental U.S. Where high precipitable water values will 
contribute to scattered convection driven strongly by diurnal influences. 
Somewhat stronger middle-level flow will extend across the middle 
Atlantic and this may contribute to longer-lived storms. Even 
so...forecast instability appears too meager to warrant severe probs 
at this time. 

Persistent east-southeasterly middle-level flow across southern Arizona would seem to favor 
robust convection developing over the high terrain and moving toward 
the lower deserts. If day2 convection does not contaminate the air 
mass across this region marginal severe threat may be warranted. 

.Darrow.. 07/29/2016