A risk of severe storms over the Chicago area Saturday
The National Storm Prediction Center preliminary outlook for Saturday has included the entire Chicago area under a risk of severe storms (see highlighted map). The area farthest south and east of Chicago is under a Slight Risk (yellow-shaded area depicting 15% chance of severe storms within 2 miles of a given location), while the remainder of northeast Illinois and northwest Indiana is under a Marginal Risk (dark-green-shaded area depicting a 5% chance of severe storms within 25 miles of a given location). The greatest threat is for damaging winds and large hail.
A west-east-oriented warm front just north of the Ohio River across Illinois and Indiana associated with developing low pressure in the central plains will move north Saturday with an extensive shield of clouds with embedded showers and thunderstorms ahead of the advancing frontal boundary. The best chance of severe thunderstorms here in the Chicago area will be later in the afternoon as the front approaches and passes through into southern Wisconsin. Where there is greatest heating will probably mark the best chance of severe storm development, thus the higher risk for severe storms is projected south and east of Chicago (see highlighted map).