Severe threat returns for northern Illinois Tuesday evening

 It was an absolutely gorgeous Monday afternoon as temperatures area wide climbed into the upper 60s and low 70s. But as the saying goes, "All good things must come to an end" and it'll be back to reality for us for the rest of the week. In fact, our temperatures may even fall below average as we near the weekend and into next week. Welcome to the wild weather March in the Midwest usually brings.

To go along with that wild weather is also the risk for strong to severe storms Tuesday afternoon and evening. The Storm Prediction Center has highlighted most of northern Illinois under a 'slight risk' for scattered severe storms, with areas along and south of I-88 under an 'enhanced risk'. Southern Wisconsin has been placed under a 'marginal risk'. What does this all mean? It means that severe storms are possible in northern Illinois, but the risks are not going to be the same for everywhere.

A weak low-pressure system moving in later tonight will drag a boundary through with it, stalling it across the state line early Tuesday morning. Associated with the front will likely be an increase in cloud cover, along with the potential for some fog. As the boundary moves through winds behind it will turn to the east and northeast. This will help pull in a cooler air mass - and an even cooler one to the east due to winds off Lake Michigan. As the boundary continues to sink to the south it'll become even more reinforced, partly due to the Lake Michigan winds, where temperatures will warm into the upper 60s and 70s south of the front. North of the front afternoon temperatures will remain in the 50s.

Moisture, instability, and wind shear will all be high along and south of the warm front which as of Monday evening appears to settle right along I-80. North of the front surface moisture and instability will be lacking, but it'll still remain high aloft (a few thousand feet above). This means any storms that develop north of the front will be elevated and pose a risk for large, possibly very large, hail. Not everyone will experience severe hail Tuesday evening, but that is our greatest threat locally while the risk for tornadoes will remain along and south of the warm front.

There may be a few showers that try to develop mid-afternoon, with a few isolated thunderstorms around 5pm and 6pm but it looks like we should see activity start to ramp up after 6pm. Scattered thunderstorms would continue through Midnight with periods of heavy rain lasting into Wednesday morning.

Be sure to remain up to date with the forecast throughout the day Tuesday. And remain weather aware should a watch be issued and prepared to act if a warning is issued.