Some risk for severe storms here – but to occur late at night in a weaker mode

The National Storm Prediction Center has most of the Chicago area under a risk for severe thunderstorms in the next 12 hours (note the headlined map has the portion north of Interstate-80 in the Marginal Risk and south of the Interstate in the Slight Risk). However the expected arrival of the showers/thunderstorms around or after midnight (band of storms approaching from the southwest), in most likely a weakened form lowers the probability of severe storms here considerably.

Once again there is the likelihood of locally heavy downpours under the strongest storms raising the risk of flooding. Storm cell movement should be progressive, not staying in one location very long with not much in the way of “training” (repeated storms over the same point). The area generally south of Interstate-80, most susceptible to heavy rains is only considered in the Marginal Risk of Excessive flood-producing rains (see the map below).

Day 1 Excessive Rainfall Forecast

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