ROCKFORD (WREX) – Storms packed quite a wallop this morning, but as they end later this morning, attention will shift toward the dangerous heat.
Northern Illinois has been impacted by several rounds of early morning storms. Vivid lightning has accompanied each round, alongside rainfall rates of nearly 3 to 3.50″ of rain per hour. The silver lining with the storm coverage this morning is that they have been moving on the order of 40 to 50 MPH, so widespread flash flooding hasn’t been a concern thus far. Storms are expected to linger through the first half of the day.
Looking upstream, two more solid lines of thunderstorms are developing in southwest Wisconsin and northeast Iowa. These storms should clear the region by shortly around noon.
Once rain and storms come to an end, a pretty quick clearing trend will take place. As the sun comes out and bakes the surface, temperatures will quickly climb into the low 90’s. There is a fair amount of uncertainty as to how far temperatures will climb this afternoon, and it all has to deal with how quickly clouds are able to clear. If cloud coverage is quick to move out, highs may top out in the mid 90’s. Current thinking keeps mostly cloudy skies around through the first half of the afternoon, which will likely keep temperatures in the lower 90’s.
Regardless of whether your location climbs to 95° or 92°, heat indices will climb to between 95° and 105° this afternoon. Remember, excessive heat warnings are in place for DeKalb, Lee, Ogle, and Stephenson Counties through much of Saturday. Heat-related illnesses become likely if you are spending a prolonged period of time outdoors, especially if you’re not taking those necessary precautions to stay cool. In Boone and Winnebago Counties, a heat advisory is in place, meaning heat-related illnesses are possible if you are spending time outdoors.
Tomorrow will be the hottest day during this heat wave. Highs top out in the upper 90’s. Depending on how much sunshine the region will see, I wouldn’t be overly surprised if someone in northern Illinois reaches 100° for a high. Outdoor activities will be dangerous tomorrow, especially between about 11 a.m. and 7 p.m., when the heat index is at its peak. A few models try to develop late-day storms, but the consensus of guidance is tomorrow will be dry.
Cooler weather is in the forecast, especially by late this weekend. Highs Saturday will be hot, with many spots likely to climb into the low to mid 90’s. Sunday will still be warm, with maximum temperatures climbing into the upper 80’s to near 90. A cold front will be pushing through Saturday into Sunday, bringing a return to cooler temperatures by the beginning of a new week. Highs into the first half of next week may only be in the lower 80’s.