(5:30PM - 1/3/20) A disturbance moving through the region will bring snow to portions of the state, this evening through Saturday afternoon.
Observational trends this afternoon suggest disturbance associated with this event will end up a bit further north and stronger than most model guidance suggested. Thus, have bumped up expected snowfall amounts for some areas in a corridor, which extends into Northwest Illinois. Model guidance suggests this disturbance and associated snow will weaken with eastward extent. However, given guidance has not done the best at handling this event thus far, am a bit weary of the output. Will continue to monitor observational trends this evening, and will have an update if needed.
A vigorous/compact disturbance and associated area of snow has been pushing across portions of South Dakota, Minnesota and Iowa today. Snow associated with this disturbance is beginning to enter Northwest Illinois at this time. This snow, which will come in waves, will then spread across portions of Northern and Central Illinois tonight and into Saturday morning. The southern edge of the precipitation shield may actually be a mix, across portions of Central Illinois. Some mixed precipitation may linger across Eastern Illinois into Saturday afternoon as well, as the disturbance departs the area. A dusting to 1" of snow will be likely for most areas, with 1-3" possible nosing into Northwest Illinois. It should be noted than even though a widespread area is expected to see snow, amounts will not be uniform, given the scattered nature of the expected snow.
In addition to the snow, winds are expected to increase tonight through Saturday morning. Wind gusts of 25-45mph will be likely across Northern and Central Illinois during that time. Some blowing snow may be possible for some areas as well.
Below is the TAM snowfall forecast for this event.
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