Multiple rounds of storms possible this week

 We may be in for an active week ahead with multiple chances for storms. There are a lot of moving parts in the forecast going forward, but here are the basics: Multiple waves of storms may be possible within the next few days, some of which may pose a risk for severe weather. Our first window is early Tuesday. This wave will develop from decaying storms forming in the Dakotas Monday night. The track of this wave is still uncertain but will dive Southeast close to the Stateline likely before 3PM. If these storms were to remain intact through the area, it would limit the next potential wave. Conversely, if those storms were to fall apart before reaching the Stateline, chances for strong storms late Tuesday evening would be higher. Similar uncertainties remain in place later in the week, but conditions appear favorable for a few waves of storms within the general region.

Right now, my thinking is that the first wave of storms will pass just to the Southwest, possibly clipping portions of the viewing area along the Mississippi River and just East. If things play out like that, the instability gradient would be shunted Southward, keeping the next wave late Tuesday night also to the South. Note: In this scenario, Rockford and areas Northeast would remain completely dry. My confidence on this scenario is low-medium at this time.

The Storm Prediction Center agrees for the most part with this assessment, placing only SW portions of the viewing area under a Level 2/5 Slight risk. Meanwhile, the rest of the Stateline only under a Level 1/5 Marginal risk. The main risk would be for damaging winds and heavy rain.

Regardless of how Tuesday plays out, Wednesday looks to build that instability gradient back up, but the afternoon should remain capped with a lack of upper air forcing to break through it. That said, another passing wave late into the evening may bring the next complex of storms after 8/9PM. With the uncertainty still in place, SPC has placed the whole Stateline under a Level 1/5 Marginal risk. Like Tuesday, the main risk would be for damaging winds and heavy rain.

In addition to the severe threat, we may also see multiple rounds of heavy rain especially if the storm complexes track over the same areas over and over again. With abundant moisture aloft, the storms will be very efficient rain producers, with 1-2"/hr rainfall rates possible. If storms were to backbuild or train at all, the risk for flash flooding would be higher. The Weather Prediction Center has placed the Stateline within the slight risk for flash flooding Wednesday into Thursday, noting a 15% chance for flash flooding guidance to be met.

Active weather with very hot and humid afternoons will continue for a few more days, with weaker scattered storms Friday before drying out into the weekend with highs back near average and less humidity.