/Issued 11:52 AM CDT, Saturday, August 31, 2013/
-Late Morning weather vapor loop. Note the swirl/twisting motion over Southern Saskatchewan…That’s a potent little disturbance which will continue to track east/southeast thru Tonight and is 1 of the reasons why there should be some thunderstorms in the Northland later Today. (Source, Unisys weather)
…Severe t-storms possible late This Afternoon/Evening…
Late This Morning a cold front extended from Northern North Dakota to Central South Dakota with low pressure averaging 1003mb over Southern Manitoba. The combination of this cold front along with a very strong disturbance tracking east-southeast across the Northern Plains and into the Upper Midwest should promote thunderstorm development later Today.
Convection should develop in the Western and Northern parts of Minnesota during the Afternoon, especially after 3 PM. Storms will then settle east/southeast into Central, Eastern, and Northeast Minnesota This Evening, probably during the 5-7 PM time frame.
The atmosphere will be unstable Today with CAPE of 1000-2500 j/kg. Lifted Indices of -3 to -8C. 0-6 KM shear and Effective bulk shear is forecast to be in the 30-40 knot range. Mid level winds out of the west will increase to 30-50 knots while a low level jet from the SW increases to 25-35 knots later Today.
Initial storms could be in the form of supercells in Western/Northern Minnesota with a risk of large hail and damaging winds. As the storms progress farther south/east This Evening the chance for supercells should diminish, but damaging winds will still be a possibility especially if a well developed bow echo/cold pool can materialize.
Be sure to stay weather aware Today. Know the difference between a watch and warning. A watch means that conditions are ‘favorable’ for the development of severe thunderstorms. A warning means that severe thunderstorms are occurring or are imminent.
Know what county you’re in in case a watch or warning is issued later Today.
Remember, all thunderstorms produce lightning. If you can hear thunder you are close enough to be struck by lightning. When thunder roars get indoors.
*Storm Prediction Center’s slight risk area (yellow area on the map) covers most of Minnesota and far Western Wisconsin for Today and Tonight.
*Large hail threat for Today/This Evening. Greatest chances with even a hatched area for a few significant hail events cover West Central and parts of Northwest Minnesota.
*Damaging wind threat for Today/Tonight.
*Tornado threat for late This Afternoon/Evening. I still don’t think there’s a very good chance for tornadoes Today. The 1km shear/helicity values aren’t the best, also I’d like to see more of a SSE wind vs. SSW wind for a greater chance for tornadoes. Either way the situation will have to be monitored, you can never rule out a quick spin-up.