Heavy rainfall, flash flooding possible tonight for parts of Northern Illinois

 [11PM] With only light rain showers so far North of I-80, our flash flooding threat will be a bit lower tonight. On and off showers remain possible with some pockets of heavy rain, but that will be rather isolated in nature with a lower risk for flooding.

[9:45PM] Latest model runs have been coming in, suggesting that the heaviest, most intense rainfall may end up South of I-80 now. That does not quite put us entirely out of the woods in Northern Illinois, but we are trending in the right direction. Light to steady showers will remain possible at times through the night with some pockets of heavy rain. The significant flash flooding will likely be a big concern South of I-80, though. Many locations already saw very heavy rain last night, with another few inches of rain possible over already saturated soils. If you know anyone in Central Illinois, make sure they are aware of the weather forecast and have steps to keep themselves safe if a flash flood warning were to be issued.

Heavy rainfall and flash flooding could be on the table for parts of Northern Illinois this evening and overnight. Our next wave of showers and storms is currently taking shape this evening in Iowa and will slide our direction along I-80 tonight.

Isolated pockets of showers will remain possible this evening, but higher coverage will arrive after 10PM-12AM. The due Easterly trajectory of this system will keep the heaviest rain just South of the Stateline, and potentially South of I-88 or even into Central Illinois. Nonetheless, strongest storms will be capable of rainfall rates near 1-3" per hour.

Back-building and training thunderstorms will quickly produce 3"+ of rainfall and develop a flash flooding threat. Luckily for Northern Illinois, I believe that threat to remain highest South of I-88 and maybe even South of I-80. We may still have pockets of heavy rain with 1-3" possible in isolated spots, but the widespread flash flooding threats should remain just to our South.

A flood watch will remain in effect through Saturday morning for Carroll, Whiteside, Ogle, Lee, and DeKalb Counties, where the locally higher risk is for flash flooding concerns. That said, be sure to heed any warnings that are issued, and I'll be sure to keep you updated through the night!