Today’s main weather story will be strong to severe thunderstorms across parts of Wisconsin. This activity will be sparked by the passage of a cold front that will be moving south through the region this afternoon and into this evening. Storms will begin to fire in northern parts of the state this afternoon before moving south and east through the evening hours. Given plenty of instability and good dynamics aloft, many of these storms could produce severe weather including large hail and strong winds. An isolated tornado can’t be ruled out either. Storms will also develop along the front farther to the west though due to limited instability, they will be more scattered and won’t be as much of a severe weather threat.
Curious about what cold fronts are and how they can cause thunderstorms? Check out my explanation of fronts over at the Weather Encyclopedia!
Instability will be widespread this evening across Wisconsin as well as nearby parts of Minnesota, Michigan, and Iowa. Instability is the fuel that thunderstorms use to grow and intensify. Values in excess of 1,000 J/kg usually support severe weather. Forecasts indicate between 3 and 4,000 J/kg of CAPE across parts of Wisconsin this evening! The extreme instability will be driven by oppressive heat and humidity with temps soaring into the 90’s this afternoon while dew points climb into the 70’s.
Curious about what CAPE is and how exactly it is fuel for thunderstorms? Check out my explanation of CAPE over at the Weather Encyclopedia!
Storms will weaken as they move towards Chicagoland later this evening and into the overnight hours.
Elsewhere across the country, generally quiet weather is expected today with scattered showers and thunderstorms expected across parts of the Southeast and Mid Atlantic. Those should remain largely below severe limits.
For more details about your specific forecast, check out the tools available at weather.us that will help enable you to stay ahead of the storm!