U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 020708 
Storm Prediction Center ac 020707 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0207 am CDT Tuesday Sep 02 2014 

Valid 041200z - 051200z 

..there is a slight risk of severe thunderstorms across WI and the u.P. Of Michigan... 

Isolated severe thunderstorms are possible across Wisconsin and the 
u.P. Of Michigan Thursday. 

..upper Great Lakes... 

A conditional severe thunderstorm threat is expected across the 
upper Great Lakes region during the day3 period. Latest short-range 
model guidance depicts a strong middle-level speed maximum that will eject 
across the northern plains into The Arrowhead of Minnesota by 05/00z with a 
corridor of 70kt+ 500mb flow expected to extend across northern Minnesota into 
northwestern Ontario. While concentrated upward vertical velocity will be north of the 
international border...pronounced surface front is expected to advance 
into western WI by early afternoon. Additionally...Stout cap is 
expected to extend across the Central Plains into west-central WI where a 
plume of very warm 700mb air with temperatures at or above 12c are expected 
at daybreak. Thunderstorms may struggle to initiate across the warm 
sector but models suggest forcing along cold front...and late day 
middle-level cooling...could be sufficient for thunderstorm development 
rooted in the boundary layer. Both the NAM and GFS suggest SBCAPE 
should exceed 3000 j/kg with surface dew points at or above 70f. Deep southwesterly flow 
and 40-50kt at 500mb suggest any storms that develop could 
organize...moving quickly downstream within a regime favorable for 
damaging winds and large hail. Southwestern extent of warm sector 
convection should be near the WI/Iowa border with any trailing storms 
likely evolving within a Post-frontal environment across the Central 

.Darrow.. 09/02/2014