Isolated storms possible late Thursday night, Summer-like warmth returns Friday

 

A surface warm front sits just west of the Mississippi River Thursday night helping ignite showers and a few thunderstorms throughout northern Illinois and Wisconsin. Further to the west severe storms have been ongoing, with several severe thunderstorm and tornado warnings in Iowa.

 These storms will continue to move east but will run into an environment with a little less instability, at least at the surface. Instability will grow aloft, however, as both warm air and an increasing low-level jet (winds just a few thousand feet above the surface) increase. This could help fuel a few isolated strong to severe storms just before sunrise Friday, especially close to the state line.

If severe storms develop hail and wind would be our biggest threats. It looks like our window for storms will increase after 3am/4am, with the threat ending after 8am. We continue to remain under a 'marginal risk' for isolated severe storms through Friday morning.

Once the warm front lifts north the chance for precipitation will mostly come to an end for Friday afternoon. Southwest winds will remain gusty through the afternoon with temperatures warming into the upper 70s, close to 80 degrees. The rise in temperatures will put a cap, or lid, on the atmosphere for thunderstorm development during the afternoon. 

 However, a cold front moving in from the west late in the day could help ignite thunderstorms during the late afternoon and evening. Because of that, a 'slight risk' for isolated to scattered severe storms remains in place for most of the region. The slower arrival of the cold front locally, the higher the chance will be for storms to develop in/around the area during the afternoon and evening. With that, I think our window for storms Friday will be centered around 5pm to Midnight. Similar to Thursday night hail and wind would be our greatest threats.

By Saturday the front will have shifted south leaving us with mostly dry and cloudy conditions. Following the warmth from Friday afternoon, Saturday will be a bit cooler with afternoon highs in the upper 50s.