Monday, July 30, 2012

Organized Severe Weather Potential in Midwest in Early August

There is a severe weather threat over the Upper Midwest and Midwest into the western Great Lakes in early August, particularly on Saturday, August 4.

A disturbance is forecast to press through the US/Canada border around Minnesota on August 4. As the disturbance enters the region, mid and lower level winds are forecast to increase in response to friction between the disturbance and a mega-ridge in the Southern US.
As the system deepens over the Upper Midwest, 850mb winds are progged to increase over the northern Plains into the Lower Great Lakes as the atmosphere encourages organized severe weather to form. The presence of instability worthy of organized severe weather looks to be significant, with instability values on the order of over 5500 j/kg in the Lower Great Lakes region, with roughly 2000-4000 j/kg in the Upper Midwest, where 850mb winds may be stronger than those to the south, thus encouraging more organized severe weather potential.
I find it likely that an organized severe weather threat will pan out in the afternoon and evening of August 4, with the Upper Midwest likely containing organized severe weather, and the Midwest dealing with a more volatile atmosphere but with less lower level winds that would specialize in severe weather. Despite the lack of favorable winds, there remains an amount of winds that I find it possible for an organized severe weather threat to develop in the Lower Great Lakes as well.



Anonymous said...

Don't you mean August 4?

Andrew said...


Aran said...

I have a feeling the SPC will issue a long range severe weather threat.