(9:30PM - 2/21/22) A winter storm is expected to impact the region and state, Wednesday afternoon through Friday morning. This winter storm is expected to produce a swath of accumulating snow/sleet/ice across the region and state during this time.
Now at the 18-24 hours point out from the beginning of this winter storm and there continues to be a bit of model guidance disagreement regarding a few aspects of this winter storm at this time. However, a large majority of model guidance continues to show a consensus solution, which is what our forecast continues to be based around with good confidence and little to no change needed with this update. Stay tuned to updates over the next several days regarding this winter storm.
An initial lead wave is expected to move through the Ohio Valley Wednesday afternoon through Thursday morning, bringing with it an initial round of wintry precipitation across the southern half of the state. Furthermore, a main storm system will develop across the Southern Mississippi Valley Thursday morning, and will then track near the Ohio Valley Thursday night, and eventually into the Mid-Atlantic by Friday morning. This storm system will bring a renewed push of wintry precipitation across the region and state, Thursday morning through Friday morning.
Wintry (Snow/Sleet/Ice) Aspect Forecast...
Wednesday Afternoon - Thursday Morning, Feb 23-24th ~ Lead Wave Event:
A lead wave is expected to move through the Ohio Valley, Wednesday afternoon through Thursday morning, with an associated area of precipitation traveling along with it. Precipitation in the form of a mix of rain/freezing rain/sleet/snow will move into Southwestern Illinois Wednesday afternoon. A transition zone will set up much of this period across Southern Illinois. Across this zone, precipitation types will from south to north will range from freezing rain to sleet to snow. This area of rain will expand as it further develops and pushes northeastward, continuing to spread across Southern Illinois Wednesday night, before ending Thursday morning. A lull in precipitation may occur between this lead wave and the main storm system to follow.
Thursday Morning - Friday Morning, Feb 24-25th ~ Main Winter Storm Event:
As the main storm system moves through the region, an associated renewed push of precipitation will move across the state and region, Thursday morning through Friday morning. This renewed push of precipitation, in the form of snow/sleet/ice, will move into Southwestern Illinois Thursday morning. This area of precipitation will then further develop and spread across much of the state from midday Thursday through late Thursday night, before ending Friday morning. A transition zone will set up much of this period across Southern Illinois. Across this zone, precipitation types will from south to north will range from freezing rain to sleet to snow. North of this transition zone across affected areas of Northern and Central Illinois, all of the precipitation will fall as snow. Snow will vary in intensity, but will generally be light, with snowfall rates of 0.5"+ an hour possible at times.
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, Thursday morning through Friday morning. This will likely enhance snowfall totals for portions of the Chicago area near Lake Michigan.
Below are the snowfall and ice forecasts for this winter storm.
-An axis of of snow/sleet accumulation of 1-3" across Northern and Central Illinois, with locally higher amounts possible.
-Ice accumulations of a glaze (Up to 0.10") to 0.10"+ across Southern Illinois.
-Widespread travel impacts likely across much of the state.
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