Extreme Heat Returns, Along with the Potential for Severe Weather Wednesday Night

Heat Advisory:

While a round of morning showers and thunderstorms rapidly slowed the heating process on Tuesday, that definitely won't be the case this afternoon. Ahead of today's extreme heat, the National Weather Service has placed a portion of Northern Illinois, including Stephenson, Jo-Daviess, Carroll, and Whiteside county, under a Heat Advisory. This advisory will be in place from 11AM to 8PM, as heat indices will have the potential to soar over the triple-digit mark.  

Hot and Humid Wednesday:

A warm front lifting to our north will help bring a much more humid air-mass into the Stateline by this afternoon. This will help our dew point temperatures climb into the low to mid 70s, making it feel warmer outside than it actually is. The combination of dew points in the 70s and air temperatures in the low 90s will push heat index values into the upper 90s and low 100s, making for a hot and humid afternoon. 

For those who have plans to be outside, please make sure to take this heat seriously. It doesn't take long for signs of heat-related illnesses to show with the heat that will be present later on. Aside from an isolated late-day thunderstorm, most of Wednesday remains dry under a mix of clouds & sunshine. You'll want to make sure to have multiple ways to get watches and warnings before heading to bed this evening, as severe potential quickly ramps up after sunset. 

Overnight Storms:

Earlier this morning, the Storm Prediction made a big upgrade to today's severe place, placing portions of northwest, central, and southeastern Wisconsin under a Moderate Risk (Level 4 of 5) for severe weather. The Stateline itself is split between three severe categories, with the highest severe threat set for our southern Wisconsin counties. Initial development looks to take place in eastern Minnesota/northwestern Wisconsin, with storms quickly merging into a line of storms by early this evening. According to the Storm Prediction Center, areas to the north (mainly in the moderate risk) have the potential to see derecho-like conditions, a term that we here at home haven't heard since last August.

Storm Timing:

Models have come into better agreement on the exact track of this line of storms, tracking them southeastward through central Wisconsin and into Lake Michigan overnight. If this scenario were to play out, the Stateline would end up on the southern edge of these storms, with a good portion of the region missing out on  thunderstorm chances as a whole. But, the smallest bump to the south will bring more impacts to the Stateline. If there were a time for the Stateline to see storms, it would be roughly from 11PM through 4AM with the greatest concerns being strong, damaging straight-line winds, as well as large hail and heavy rainfall. Thunderstorm chances continue into early Thursday morning, with conditions slowly drying out into the afternoon. While Thursday will still feel muggy at times, conditions quiet down and cool down into the end of the work week, with highs dropping into the low 80s.