Timing out Wednesday's severe threat

 

You could feel the climb in humidity Tuesday afternoon as air temperatures warmed into the upper 80s and the heat index in the low 90s. It wasn't anything too terribly humid but more so than what we've felt the last few days. The healthy development of a nice cumulus cloud field was an indication of both the rise in moisture and instability.

The Stateline is sandwiched between two storm systems - one to the south bringing scattered thunderstorms downstate and another one over the Plains. Conditions will remain quiet through the rest of the evening, but it'll stay muggy. Temperatures will slowly drop but only down into the low 70s - leaving us right around 70 degrees for the start of Wednesday.

As a little piece of energy moves in from the south late Tuesday night, we could see an isolated shower or two, but most are expected to stay dry. Some patchy fog will be possible but isn't expected to be widespread. 

A slight risk for scattered severe storms will be possible Wednesday, especially during the afternoon. The biggest threats are likely to be damaging winds, but an isolated tornado or two and large hail can't be ruled out. This would be especially true for any storms that develop initially over southwest Wisconsin and northwest Illinois.

Storms ongoing over the Plains will continue to grow through the evening, shifting east with time. As they move into the Midweset there should be an overall weakening trend early Wednesday. A remnant low will develop which will aid in the redevelopment of thunderstorms downstream Wednesday afternoon. At the earliest, storms look to form close to the Mississippi River around Noon - quickly zipping east during the afternoon. This would put storms at their earliest in northwest Illinois around 1pm/2pm. The main window looks to be from roughly 2pm to 6pm, with storms shifting to the east after 7pm across the entire Stateline.

Heavy rainfall will also be a concern, especially with the high amounts of moisture that'll be in place. Rainfall totals over an inch will be possible. At this moment, it doesn't look like the set-up we experienced last Thursday with the flash flooding, but it is something to keep an eye on as the storms unfold.