Tue-Thur, Feb 1-3rd Major Winter Storm Recap

(5:45PM - 2/5/22) A brief recap regarding the Tue-Thur, Feb 1-3rd major winter storm that produce a swath of significant accumulating snow/sleet/ice across the region and state during this time.

Summary...
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 occurred across the region and state, midday Tuesday through Wednesday evening. Furthermore, a storm system developed in the Southern Plains on Wednesday, and then tracked through the Tennessee Valley on Thursday, and eventually into the Mid-Atlantic region on Friday. This storm system brought a renewed push of precipitation across the region and state, Wednesday night through Thursday night.

Summary...
Tuesday Midday - Wednesday Evening, Feb 1-2nd ~ 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 occurred across the region and state, Tuesday morning through Wednesday evening. 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 then continued in varying intensity across a large portion of Northern and all of Central Illinois, from transition time through Wednesday afternoon and evening. Periods of moderate to heavy snow occurred at times, with more lull-like periods of lighter snows likely as well. Snowfall rates upwards of 1"+ an hour also occurred at times in the heavier periods of snow, especially Tuesday night through Wednesday morning. Across southern portions of Central Illinois, this is where the overall transition zone set up with mixed precipitation set up Tuesday night into Wednesday morning. Across this zone, precipitation types from south to north ranged from freezing rain to sleet to snow. This transition zone shifted southward Wednesday morning across Southern Illinois, and will eventually stalled out across Southern Illinois during the day on Wednesday.

Wednesday Night - Thursday Evening, Feb 2-3rd ~ Main Storm System:
As the overrunning precipitation continued across the state into Wednesday evening, the main storm system will also move into the region. A renewed push of precipitation moved 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, moved into Southwestern Illinois Wednesday night. This area of snow then spread across portions of Central and Southern Illinois, from  Wednesday night through Thursday afternoon, before ending by Thursday evening. Periods of moderate to heavy snow occurred at times, with snowfall rates of 1-2" an hour having also occurred at times. Additionally, a period of windy conditions occurred Wednesday morning through Thursday afternoon. During this time wind gusts upwards of 25-40MPH occurred across portions of Central and Southern Illinois, which caused blowing and drifting snow. Further south across Southern Illinois, the transition zone of mixed precipitation was in place Wednesday night through Thursday morning. Across this zone in Southern Illinois, precipitation types from south to north will range from freezing rain to sleet to snow. This transition zone eventually changed over to snow during the day on Thursday, before ending.

In additional to the synoptic aspect to this winter storm period, conditions were favorable for a bit of lake enhanced and lake effect snow across portions of Northeast Illinois, Wednesday night through Thursday evening. This enhanced snowfall totals a bit for portions of Northeast Illinois near Lake Michigan.

Wrap Up...
-An axis of of significant snowfall totals occurred across the heart of the state, with snowfall totals upwards of 8-15" in the main corridor, with locally higher amounts. Snowfall amounts quickly tapered north and south of this main axis, across Northern and Southern Illinois.
-An axis of significant ice accumulations of 0.10-0.50" occurred across Southern Illinois.
-Windy conditions on Wednesday and Thursday caused blowing and drifting snow across the heart of the state.
-Significant and widespread travel impacts occurred across much of the state, especially across the heart of the state

​​Below are map representations of the final forecasts and observed totals of snowfall and ice across the state and adjacent areas. 

​Observed Snowfall Totals

Observed Ice Totals

Final Snowfall Forecast

Final Ice Forecast

JP