The National Storm Prediction Center has outlined an area of severe Thunderstorm risk over Wisconsin and portions of Minnesota, Iowa, northwest Illinois into the central and southern Plains later this afternoon and tonight. The greatest Risk (yellow-shaded Slight Chance on the headlined map) is over Wisconsin. As a cold front moves southeast across this warm moist unstable area, a band of strong to severe storms is expected to develop.
Strongest storms will occur in the peak-heating afternoon/early evening hours, but weakening storms will continue later this evening/overnight along and ahead of the cold front as it approaches and pushes into our area. As a result, the westernmost sections of the Chicago area are included in the Marginal Risk (dark green) area.
The maps below depicting the probability of thunderstorms within 12 miles of a given location, display in greater detail the areas with highest chances of thunderstorms this afternoon into the overnight. The Chicago area is generally positioned in the 10 to 20% probability area.