(10:15PM - 11/23/20) A storm system moving through the region the next few days will bring a period of snow to Northern Illinois, tonight through midday Tuesday.
An area of precipitation developed across Nebraska, Kansas, Iowa and Missouri today, as warm air advection has been increasing... associated with an incoming storm system. This area of precipitation has been expanding and steadily pushing northeastward... and has spread across Central Illinois this evening and early tonight. Areas of all snow have occurred along the Illinois/Missouri and Illinois/Iowa border region of Western Illinois, while generally all rain has occurred across Central Illinois. This precipitation will continue to spread northeastward, tonight through midday Tuesday. With colder air in place as this precipitation moves through, a large amount of the precipitation will fall as snow across Northern Illinois during this time-frame. A couple hour period of snow is likely across a good portion of Northern Illinois tonight through late Tuesday morning. Beyond this time-frame, temperatures will warm into the 40's, allowing snow to change to rain and any snowfall accumulation to quickly melt. Snowfall totals will generally range from a dusting to around 1" across much of Northern Illinois. However, an area of higher snowfall totals will be possible near the Illinois/Wisconsin border and in Northwest Illinois...where a dusting to 2" of accumulation will be possible (locally higher amounts possible). Across Central Illinois, precipitation will mainly be rain...but could flip to rain/snow mix or all snow for a brief time late tonight or early Tuesday morning. Little to no snowfall accumulation is expected.
Below is the snowfall forecast for tonight through midday Tuesday.