RISK FOR SEVERE STORMS THIS AFTERNOON/EVENING
As discussed in our morning update, we do run the risk for a few strong to severe thunderstorms this afternoon and evening. We are seeing some non-severe thunderstorms this morning with small hail and gusty winds. This is out ahead of a potent area of low pressure currently strengthening in Nebraska.
The setup for this afternoon and evening is complex, but key ingredients will be coming together to produce a brief window of opportunity for a few severe storms.
TIMING: 4pm to 9pm this evening.
SETUP: A warm front currently to the south will begin to rapidly lfit north into the area this afternoon in response to the strengthening low to our west. This will draw up a warm and moisture rich airmass to our south where temperatures will quickly rise into the 60s and even low 70s.
Meanwhile, a cold front will move in from the west sparking scattered thunderstorms by 4pm just west of the Mississippi River. These initial storms will be capable of producing large hail, damaging winds, and an isolated tornado.
As the storms quickly work east, some will likely encounter the advancing warm front. Any storm that interacts with the boundary will be capable of producing an isolated tornado. That risk appears to be highest along and north of Interstate 80, including the immediate Sauk Valley.
More than adequate wind shear and other storm factors will allow storms to rotate easily, the key will be any storm that can interact with the aformentioned warm front to actually produce a tornado.
The position of the front can still change in the next few hours and will remain critical as to where the highest tornadic threat will be this afternoon. We'll have further updates as warranted regarding the previously mentioned threats.
Storm motion will be fast, up to 50 and 60 MPH in some cases leaving little time to take action once a warning has been issued. Make sure you have a way to receive warnings today.