Mesoscale outlook – strong to severe thunderstorms expected to move through northwest Illinois between 6:30 and 9PM CDT
The threat for damaging winds will continue across the Severe Thunderstorm watch area this evening, while a risk for isolated damaging downbursts will exist just south of the Watch area across northwest Illinois early this evening. The southern end of the band of storms could pass close to and south of Rockford along the I-39 corridor before moving northeast into Wisconsin.
A small bowing line of severe thunderstorms extended from far southwest WI into northeast IA at 6:15PM CdT, with a history of strong/severe winds. Other severe storms with marginally severe hail and the potential for strong downburst winds were occurring farther east along a frontal boundary to Sheboygan County, WI. The downstream environment will remain moderately unstable into south-central WI, with somewhat drier air closer to the Lake Michigan shore resulting in weak buoyancy. Overall, a continued risk for damaging winds and isolated large hail should continue through around 9PM CDT as storms move east/northeast across the watch area. Isolated severe storms were occurring south of the watch from the Davenport, IA vicinity into adjacent portions of northwest IL. A recent wind gust to 75 mph was reported in Davenport with a localized downburst. Moderate/strong surface-based instability will remain supportive of strong/severe gusts as storms move northeast into the watch area over far northwest IL during the next 1-2 hours.