A Slight Risk for severe thunderstorms continues across southern Wisconsin for this afternoon and evening. The combination of nearby deepening low pressure, a warm front, and a passing cold front will increase the chance for strong to severe thunderstorms across southern Wisconsin this afternoon and evening.  

The below graphic from the Weather Prediction Center illustrates the location of the fronts and low pressure systems at 7 pm this evening:  

The Storm Prediction Center in Norman Oklahoma still has a portion of southern Wisconsin in a Slight Risk for Severe Thunderstorms this afternoon and evening.  The Slight Risk area is along and south of a line from just north of Milwaukee to just south of Madison to Platteville.  This also includes the Janesville, Monroe, Racine and Kenosha areas. A Marginal Risk is in effect north of this line. 

Scattered strong thunderstorms are expected to develop this afternoon and evening as a strong front moves through southern Wisconsin and nearby Low Pressure rapidly intensifies.  A few of these thunderstorms may become severe with the highest probability across far southern Wisconsin.  The primary severe weather risks are large hail and damaging winds.  An isolated tornado is possible near Darlington and Monroe.  

Atmospheric instability will be greatest above the surface this afternoon and evening.  The greatest instability will be closer to the Illinois border where an isolated tornado is possible.  The instability aloft and strong wind shear in the atmosphere may still allow the strong thunderstorms to become severe producing large hail and damaging winds. Strong shear can still support strong to severe thunderstorms even with lower atmospheric instability.

Air is considered unstable if it continues to rise when given a nudge upward (or continues to sink if given a nudge downward). An unstable air mass is characterized by warm moist air near the surface and cold dry air aloft.

Everyone will need to pay close attention to radar and the latest weather forecasts today, and be ready to take action should severe weather watches and/or warnings be issued. Stay tuned to your NOAA Weather Radio for the latest alerts if severe weather watches and/or warnings are issued. Here is a link to the latest Hazardous Weather Outlook from the NWS in Milwaukee/Sullivan.

Here is a link to a video briefing regarding the risk for severe weather across southern Wisconsin later today and this evening.

Strong southwest winds are expected after the cold front passes by and the low pressure system tracks into central and northern Wisconsin.  Southwest wind gusts of 50 to 55 mph are possible on Wednesday across most of southern Wisconsin.  A High Wind Watch is in effect for most of the area.

The below graphic depicts estimated wind gusts around 1 pm Wednesday:

Would you like to learn more about severe weather and become a Skywarn Severe Weather spotter for the National Weather Service and your community? The National Weather Service in Milwaukee/Sullivan will be presenting severe weather spotter training sessions across southern Wisconsin through mid-April. Check dates and locations at www.weather.gov/mkx/spotter-schedule.

National Weather Service
Kavinsky