Tue-Thur, Feb 1-3rd Major Winter Storm Update #5

(10:45AM - 2/2/22) A major winter storm will continue to impact region and state, through Thursday night. This winter storm will produce a swath of significant accumulating snow/sleet/ice across the region and state during this time.
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Summary...
A winter storm continues to unfold across the region, and has been impacting the state since midday Tuesday. Last night into this morning the first part of this winter storm brought a widespread accumulating snowfall occurred across Northern and Central Illinois, with mixed precipitation across portions of Central Illinois as well. This first part of this winter storm will continue to affect the state through this evening. The second part of this winter storm will affect the state, tonight through Thursday evening. Regarding the second part to this winter storm, model guidance continues to be in fairly good agreement in showing a consensus solution. However, this solution has trended a bit south over the past 12-18 hours. Thus, this additional update has been warranted to update forecast information.

​A cold front moved across the region on Tuesday, associated with a storm system moving through Southern Canada. This frontal boundary became nearly stationary across portions of the region and Southern Illinois Tuesday night into Wednesday. With ample advection from the south over-topping this frontal boundary, a widespread overrunning precipitation event has been occurring across region and state, Tuesday morning through this evening. Furthermore, a storm system will develop in the Southern Plains today, 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, tonight through Thursday night.

Forecast...
This Morning - This Evening, Feb 2nd ~ Overrunning Precipitation Event:
A cold front moved through the region on Tuesday, associated with a storm system moving through Southern Canada. This frontal boundary slowed and became nearly stationary across the region and southern half of the state Tuesday night into today. With ample advection of mild/moist air from the south over-topping this frontal boundary, a widespread overrunning precipitation event has been occurring across the region and state, Tuesday morning through this morning. Precipitation, in the form of rain, developed and spread across the state Tuesday morning into Tuesday evening. As colder air filtered in on behind the slowing cold front pushing through the state, rain transitioned to a mix and snow across affected areas of Northern and Central Illinois Tuesday evening into Tuesday night. Snow will continue in varying intensity across a large portion of Northern and all of Central Illinois, through this afternoon and 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" an hour will be likely at times in the heavier periods of snow, especially through this afternoon. Across southern portions of Central Illinois, this is where the overall transition zone set up with mixed precipitation set up Tuesday night into this morning Across this zone, precipitation types from south to north ranged from freezing rain to sleet to snow. This transition zone has been shifting southward this morning across Southern Illinois, and will eventually stall out across Southern Illinois today.

Tonight - Thursday Evening, Feb 2-3rd ~ Main Storm System:
As the overrunning precipitation continues across the state into this 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, tonight through Thursday evening. This renewed push of precipitation, in the form of snow, will move into Southwestern Illinois tonight. This area of snow will then spread across portions of Central and Southern Illinois, from tonight through Thursday afternoon, before ending by Thursday evening. Periods of moderate to heavy snow will be possible at times, with snowfall rates of 1-2" an hour likely at times. Additionally, a period of windy conditions is possible Wednesday night through Thursday evening. 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 will be in place toight 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 Thursday morning, continuing into Thursday evening before ending.

In additional to the synoptic aspect to this winter storm period, conditions will be favorable for lake enhanced and lake effect snow across portions of Northeast Illinois, this evening through Thursday night. This will likely enhance snowfall totals for portions of the Chicago area near Lake Michigan.

​Impacts...
-An axis of of significant snowfall totals across the heart of the state, with upwards of 7-15" in the main corridor, with locally higher totals possible. 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, through Thursday evening.
​-This is a long duration winter storm, with impacts across the state spread out over a two day period.

​Below are the snowfall and ice forecasts for this winter storm.

JP