Saturday, July 5, 2014

Severe Weather Discussion for Sunday, July 6th

Severe weather is possible on Sunday, July 6.

The Storm Prediction Center has highlighted portions of Wisconsin, Minnesota, Iowa, Illinois, Indiana, and Missouri for severe weather on Sunday. Within the aforementioned regions, northwest Illinois, Wisconsin, northeast Iowa, and extreme southeast Minnesota look to have the highest severe weather potential.

Projections of convective available potential energy (CAPE), a measure of how unstable the atmosphere is projected to be for Sunday night, give away the reason the aforementioned states have an elevated risk. We see CAPE values exceeding 5000 j/kg over Iowa and Wisconsin, nearly encompassing the entirety of that 30% severe weather risk area. It is apparent that high instability will be the focal point of Sunday's severe weather event. While the highest threat should remain over IA/IL/WI, I'm seeing continued high instability readings across Missouri and Illinois, areas that should also see some active weather tomorrow.

I am concerned that convection in northern Illinois and southern Wisconsin may not be fully realized after analyzing projected atmospheric soundings. Soundings valid for Sunday evening show that temperatures needed for thunderstorms to form in northern Illinois will need to break into the low 90s, even though the high temperature in Chicago is projected to be 88. I do believe active weather will go through these regions, but I wanted to voice my concerns of a potential letdown, per se, of any potential severe weather in these areas.