(11:45AM - 2/1/22) A major winter storm is set to significantly impact the region and state, this afternoon through Thursday evening. This winter storm is expected to produce a swath of significant accumulating snow/sleet/ice across the region and state during this time.
While model guidance continues to be in some form of consensus regarding this period, there still does continue to be some disagreement within model guidance at this time, and the overall consensus of model guidance has even shifted a bit over the pas 12-18 hours. Stay tuned to updates over the next several days regarding this winter storm, as additional adjustments could be necessary.
A cold front will move through the region today, associated with a storm system moving through Southern Canada. This frontal boundary will then become nearly stationary across the region and southern half of the state tonight into Wednesday. With ample advection from the south over-topping this frontal boundary, a widespread overrunning precipitation event is expected across the region and state, this afternoon through Wednesday evening. Furthermore, a storm system will develop in the Southern Plains on Wednesday, and will then track through the Tennessee Valley on Thursday, and eventually into the Mid-Atlantic region on Friday. This storm system will bring a renewed push of precipitation across the region and state, Wednesday night through Thursday evening.
This Afternoon - Wednesday Night, Feb 1-2nd ~ Overrunning Precipitation Event:
A cold front will move through the region today, associated with a storm system moving through Southern Canada. This frontal boundary will then become nearly stationary across the region and southern half of the state tonight into Wednesday. With ample advection of mild/moist air from the south over-topping this frontal boundary, a widespread overrunning precipitation event is expected across the region and state, this afternoon through Wednesday evening. Precipitation in the form of rain is beginning to develop this morning across portions of Missouri and Central Illinois, with further development expected into this afternoon. This area of rain will expand as it further develops and pushes northeast, spreading into other portions of Northern, Central and Southern Illinois this afternoon and evening. As colder air filters in on behind the slowing cold front pushing through the state, rain will transition to a mix and snow across affected areas of Northern and Central Illinois this evening into tonight. Snow will then be likely in varying intensity across a large portion of Northern and all of Central Illinois, from transition time this evening/night through Wednesday evening. Periods of moderate to heavy snow will be possible at times, with more lull-like periods of lighter snows likely as well. Snowfall rates upwards of 1-2" an hour will be likely at times in the heavier periods of snow, especially tonight through Wednesday afternoon. Across southern portions of Central Illinois, this is where the overall transition zone will set up with mixed precipitation being likely. Across this zone, precipitation types from south to north will range from freezing rain to sleet to snow. This transition zone will likely slowly shift southward through the day on Wednesday, eventually stalling out across Southern Illinois by Wednesday afternoon and evening.
Wednesday Night - Thursday Evening, Feb 2-3rd ~ Main Storm System:
As the overrunning precipitation continues across the state into Wednesday evening, the main storm system will also move into the region. A renewed push of precipitation will move across the state and region associated with the main storm system, Wednesday night through Thursday evening. This renewed push of precipitation, in the form of snow, will move into Western Illinois later Wednesday evening. This area of snow will then spread across Central Illinois through Wednesday night and much of the day on Thursday, before ending by Thursday evening. Periods of moderate to heavy snow will be possible at times, with snowfall rates of 1"+ an hour likely at times. Additionally, a period of windy conditions is possible Wednesday night through Thursday afternoon. During this time wind gusts upwards of 25-40MPH will be possible, which will cause blowing and drifting snow. Further south across Southern Illinois, the transition zone of mixed precipitation that had been across portions of Central Illinois Tuesday night into Wednesday afternoon will shift southward, settling across much of Southern Illinois Wednesday afternoon/evening through midday Thursday. Across this zone in Southern Illinois, precipitation types from south to north will range from freezing rain to sleet to snow. This transition zone will eventually change over to snow midday Thursday, continuing into Thursday afternoon before ending.
In additional to the synoptic aspect to this winter storm period, conditions will be favorable for some lake enhanced and lake effect snow across portions of Northeast Illinois, Wednesday evening through Thursday evening. This could enhance snowfall a bit for affected areas.
-An axis of of significant snowfall totals across the heart of the state, with upwards of 9-17" in the main corridor. Snowfall amounts will quickly taper north and south of this main axis, across Northern and Southern Illinois.
-An axis of significant ice accumulations of 0.10-0.50"+ across Southern Illinois.
-Significant and widespread travel impacts likely across much of the state, Tuesday evening through Thursday evening.
Below are the snowfall and ice forecasts for this winter storm.