Mild air has definitely spread over the Midwest today. An upper level low that moved from northern Mexico Wednesday to the upper Midwest today brought with it much needed rain and the mild air. The graphic from CoCoRAHS shows the overnight rainfall over most of northern Illinois. Rainfall amounts ranged from roughly 3/4 to 1 1/4 inches. Details here and here.
The upper low has departed, leaving the Chicago metro area mild and damp. With the lingering drought, all precipitation is welcome. Our normal high is only 31, we are 20-25 degrees normal above normal with today's highs into the 50s. As of noon, the clouds have actually broken up from about Springfield south. With the sun, temperatures are jumping into the 60s downstate.
The metro area will stay mild through tonight and roughly midday Saturday before colder air finally moves in. Saturday night will see temperatures fall back below freezing. between 9:00 p.m. to midnight from west to east over the metro area. It is also in this time frame that a new area of precipitation will spread from southwest to northeast over the area. While the heavy precipitation will fall from northeast Indiana to southern Illinois close to the cold front, the metro area will be on the northwest edge of the precipitation band.
For the metro area right now it looks like a little rain, then sleet, and finally a little snow will fall in a time window from roughly 9:00 p.m. to 3:00 a.m. A couple of inches of snow may accumulate. Timing is really critical here with the precipitation moving in and out along with the timing of the cold air. Just a few hours either way will make quite a difference on any snow amounts. From Sunday on it looks back to reality with highs from the mid 20s to low 30s next week.
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