Turning hot and windy Thursday; Isolated afternoon severe storms possible

 
The fog early Wednesday morning was thick for some but was quick to lift, leaving skies partly cloudy throughout the afternoon and evening. While the clouds have tried to bubble up over the last couple of hours, any shower/storm activity has so far been fairly limited. Temperatures have been able to warm into the low 80s as a result. But the focus in the short-term remains on the conditional severe threat Thursday afternoon, along with the heat/humidity and gusty winds.

Wednesday evening/night

Isolated showers and thunderstorms remain possible through sunset Wednesday evening, but the overall coverage is only around 20 percent. With some breaks in the cloud cover the last couple of hours afternoon temperatures have been able to warm into the low 80s with just a touch more humidity. Outside of the isolated shower chance most of the area will remain dry through the night.

Temperatures tonight will fall back into the low 60s as some patchy fog develops from the east. This fog will once again develop off of Lake Michigan as the cool winds move onshore. But unlike Tuesday night, it doesn't look like the thicker fog will make it this far west. Patchy fog will be possible through sunrise Thursday.

Thunderstorms developing over the Plains in response our next storm system will move east into the Midwest early Thursday. It's possible that some of those storms, while in a weakening state, could broadbrush parts of the viewing area during the morning. However, this possibility remains on the lower side.

Thursday

A warm front will lift north during the morning Thursday as low pressure moves into the Upper Plains and Midwest. This will quickly push temperatures into the upper 80s, possibly low 90s, during the afternoon. The forecast high for Rockford is 90 degrees. If we do end up reaching 90 it would at least tie the record high for the 15th of May, which was set back in 1944. At the same time a very warm air mass will be moving in aloft, capping our atmosphere to any storm development through at least early afternoon. Gusty southerly winds will also draw up quite a bit of moisture pushing dew point temperatures into the low 60s. This combination will help build up quite a bit of instability throughout the region during the afternoon.

Thunderstorms are expected to quickly develop closer to the surface low Thursday near Minnesota, moving into Wisconsin during the afternoon and early evening. These storms will extend south down towards Madison and Janesville, moving east/northeast towards Milwaukee and Green Bay Thursday evening.

The highest chance - and highest confidence - for severe storms Thursday is to the north and east where the Storm Prediction Center has an 'enhanced risk' for severe storms. South of there, into northern Illinois, the confidence is a little less on storm development. This is because of the lingering cap that may still be in place over parts of northern Illinois, along with a little less forcing from the low itself (as that is further north).

If storms were to develop over northern and northeast Illinois, they would most likely be isolated rather than widespread but would quickly turn severe. And even if one or two storms form the chance of those turning severe is fairly certain.

Friday

Temperatures will stay warm Friday afternoon, rising into the low 80s. Drier air quickly moving in behind Thursday's cold front will cause relative humidity values to drop throughout the day. This combined with the strong southwest winds will greatly increase the fire risk during the afternoon. There is also a risk for blowing dust and dirt with the now freshly plowed fields in northern Illinois.