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Thunderstorms over the Great Lakes will bring a severe threat this evening.

Cooler and drier weather follows a cold frontal passage Tuesday.

Discussion

Disturbance rippling across the Great Lakes with seasonally strong northwesterly flow aloft will offer a severe storm threat this evening. Ongoing convection near Lake Michigan continues to grow upscale this afternoon and will likely head south-southeast as a mature MCS early this evening. With moderate instability (somewhat dampened by an elevated smoke layer across our area) and around 50 knots of effective bulk shear, there will be a increasing threat of damaging winds accompanying the storms. It is likely the storm mode will be somewhat linear by the systems arrival in our northwestern counties, but can't rule out a brief large hail and spin-up/QLCS tornado threat as well. In addition, very heavy rain could cause localized flash flooding as well. especially in flood-prone areas.

The main uncertainty with this system is how far east the MCS reaches. The main instability gradient looks to be setting up near and west of the Interstate 75 corridor. If this holds, the highest threat of damaging winds will coincide with this region. We will continue to monitor storm- and meso-scale evolution as the event unfolds.

A cold front will sweep southeast through our local area Tuesday morning. Can't rule out a few showers or an isolated storm along the front, but severe threat looks to be low at this time. Northwesterly winds behind the front will slowly bring slightly cooler and drier air lasting through most of the week. Temperatures will be a bit below normal through at least Thursday and potentially into Friday.