Severe Threat for Saturday

After a warm and quiet Friday, thunderstorms look to return to the forecast on Saturday. A shortwave in the upper levels of the atmosphere and an associated cold front will swing through the region Saturday evening. Along and ahead of this front will exist the threat of showers and thunderstorms in Illinois and Wisconsin. Forecast models are not in perfect agreement regarding when and where the more concentrated areas of rain and storms will be, but it appears that there will be some scattered rain showers in the morning followed by quiet conditions around lunchtime. Then, from roughly 3-9PM scattered showers and thunderstorms look likely as the front edges into the region.

If enough sunshine pops out during the late morning and early afternoon hours, there could be modest instability present (known as CAPE). The map to the right represents CAPE that may exist Saturday afternoon. The blue-green area extending from near St. Louis into Central Wisconsin is immediately ahead of the front, which is where thunderstorms will likely exist. If that much CAPE can develop, there is a risk of a few strong to severe thunderstorms. An additional component meteorologists look at for the threat of severe weather is moisture. Typically, the higher the moisture content, the better the chance of stronger storms and heavy rain.

Looking at the image at the left, you can see the expected dew points Saturday afternoon. This particular model suggests dew points in the lower 60s, which would be sufficient to support at least a few strong storms and heavy downpours in the stronger cells that develop. All in all, the severe weather threat doesn't look impressively high, but according to the Storm Prediction Center we are under a low risk for severe weather.