A SEVERE THUNDERSTORM WATCH has been issued for Lee, DeKalb and McHenry counties until 2am Thursday as isolated thunderstorms were quick to develop over southeast Lee and DeKalb counties.
The cap on our atmosphere is still rather strong Wednesday night, really limiting thunderstorm growth. The storms over central DeKalb County did turn severe closer towards Chicago, but then were quick to weaken. Isolated showers and storms developed over southeast Wisconsin, moving out over Lake Michigan earlier, likely in an area where the cap was a little weaker. Additional light showers have been showing up on radar over the last hour and these will need to be watched for any further development into the night. I’m still holding on to the threat for isolated strong to severe storms as the moisture and energy are still rather high in the atmosphere. It’s really hard to say where exactly these storms may form through the night as areas where the cap is a little weaker, we may see faster growth.
The greatest risk for thunderstorms, should they form tonight, would be hail and wind. Given the moisture and wind shear in the environment tonight, the threat for isolated tornadoes will also be present – but low at this point.