Flash flooding, severe storms again possible this evening

Believe it or not, yesterday was only the 4th time this year Rockford observed 1" or rain or more. However, there were locales closer to the Illinois and Wisconsin border that wound up with 3"-6" totals.

 

 

 

A similar scenario is expected today as a nearby boundary and compact low pressure system, also known as a Mesoscale Convective Vortex (M.C.V), combine to bring the potential for additional flash flooding and severe weather. 

In fact, prior to sunrise, the National Weather Service placed a good portions of northwest and north central Illinois under a Flash Flood Watch. The portion of the watch that contains Winnebago, Boone, Ogle, and Lee County will run from 2PM-10PM. Stephenson, Jo-Daviess, Carroll, and Whiteside Counties will be under the watch until 1AM Saturday. That's because the storms that form along these two meteorological features could produce rainfall rates up to 2" per hour, furthering the risk for dangerous flash flooding.  

Here's the timeline. A few thunderstorms, mainly non-severe, will push through during the morning and early afternoon hours. A secondary round is then scheduled to develop along the approaching M.C.V in central Iowa just after midday. These thunderstorms will track east with time, pushing through the region between 5PM-11PM. Like yesterday, these will pose a risk for damaging winds, large hail, and even a few tornadoes cannot be ruled out.

Today's risk will be more scattered which is why the Storm Prediction Center has placed the entire area under a level 2 Slight Risk. Severe potential carries on into the start of the weekend as the associated cold front slides through. The risk is a bit more isolated, hence the level 1 Marginal Risk. This will mainly be for strong winds and large hail. Temperatures over the weekend will end up back in the low 80s.