Currently across the area, we in Illinois sit between high pressure off to our east across the Mid Atlantic region and developing low pressure to our west across the central plains. This is leading to a tight pressure gradient and strong southerly winds across our state this afternoon and will continue into the evening hours.
Temperatures will continue to slowly rise through the rest of the day and into the evening/overnight hours with strong warm air and moisture advection into all of Illinois via the strong southerly winds. There could be some fog as well across portions of the region with the moisture overrunning the still existing snow pack. The snow should rapidly melt across northern Illinois by tomorrow and temperatures sky rocket into the mid to upper 50’s by early tomorrow afternoon ahead of this cold front.
The approaching front will bring an increase in rain showers during the morning and afternoon areas as well. Below is a forecast loop showing increasing rain showers across most of Illinois during the morning and afternoon hours.
The cold front will move east through Illinois tomorrow from west to east during the evening hours with temperatures quickly dropping into the 20’s by late tomorrow evening across the entire state.
As cold air advection commences behind the cold front, there should be some mixed precipitation on the backside of the cold front ass it pushes east across Illinois. This could be in the form of freezing rain, sleet, and snow until any leftover moisture moves off to our east. These situations tend to be a little difficult to forecast as it will depend on how quickly the low level cold air can catch the precipitation as it moves east across our state. Below is one high resolution models take on what could happen tomorrow afternoon and through the evening hours.
Broad high pressure will build into part of the Midwest Friday with the center of the surface high up over the northern plains. This will lead to more sunshine across most of the state but daytime highs will remain in the 20’s.
Also, given somewhat favorable northeast wind trajectories off lake Michigan with the surface high to our west and steeper lapse rates over Lake Michigan with the cold air aloft, we could see some lake effect snow showers on the west side of the lake on Friday afternoon and into the evening hours. Several high resolution models are beginning to hint at this as we get closer and there could even be some light accumulations from this. We will keep you updated on this as we get closer.
What looked like a strong storm system passing to our southeast on Saturday now looks like a much weaker system as model guidance has come around to a better consensus on the strength and path of that surface low into the Ohio Valley. This will leave us in Illinois (except across far southern Illinois where they could see some snow with this system if it tracks far enough to the northwest) with continued cold and quiet conditions over the weekend with below normal temperatures. Some model guidance is showing a weak snow system moving into parts of central and northern Illinois late Sunday night and into Monday morning. We will keep an eye on this and also updated you on any possible accumulations as we get closer.