Heat Wednesday helps fuel afternoon thunderstorms

 

For the third straight day in a row, the high temperature for Rockford reached 94 degrees with an afternoon heat index of 99 degrees. Monday's peak heat index did reach 100 degrees for a short time during the afternoon. Temperatures Wednesday are likely to reach the 90-degree mark once again, but afternoon isolated to scattered thunderstorms may work to 'cool' some locations off during the afternoon.

Locally, skies will remain clear Tuesday evening as a line of severe thunderstorms stretches from Minnesota to Kansas. These storms are forming along a cold front that'll pass through the Stateline Wednesday afternoon. As it does, scattered thunderstorms will be possible.

Heading into Tuesday night, temperatures will only fall into the low to mid 70s, with Rockford's temperature dropping to 74 degrees. The storms to the west will gradually move east but weaken as they do so. However, a remnant outflow boundary may push into far northwest Illinois early Wednesday bringing with it a chance for an isolated shower or storm through sunrise.

As the cold front moves further east, it'll interact with the hot and humid conditions across southern Wisconsin and northern Illinois. This will allow isolated storms to begin to develop mid to late afternoon, becoming more scattered into the evening. While there isn't much forcing aloft for the storms to continue to grow, the heat and moisture, combined with the incoming cold front, will be enough to allow some of the storms to turn strong to severe. If severe storms do develop, they would pose a damaging wind threat through early evening. For this reason, the Storm Prediction Center has highlighted northern Illinois and southern Wisconsin under a 'marginal risk' for isolated severe storms during the afternoon and evening.

The storm threat Wednesday will remain scattered, meaning not everyone will experience rain or storms. This is a pattern very typical for the summer months as convective type storms become more common than widespread rainfall. Widespread rain can occur, but it often comes with the risk of flooding due to repeated rounds of heavy rain producing thunderstorms.

Scattered storms will also be possible Thursday as the cold front stalls across the area. It is possible that the front lifts far enough north into Wisconsin to bring temperatures during the afternoon back into low 90s, however. Which, if that occurs, the heat index will warm back into the mid and upper 90s.

By Friday the front will lift back north as a warm front bringing afternoon temperatures back into the low 90s, with the 90s continuing Saturday.