(11:30AM - 2/12/20) A storm system moving through the region today into Thursday will bring accumulating snow to a large portion of the state.
As expected, a complex setup is unfolding across the region...A disturbance across the Southwestern US has started to eject out into Central US. As this is happening, a disturbance has dropped out of Canada, and into the Central US. Both of these disturbances are interacting, leading to the development of a storm system, which will move through the region today into Thursday. Not surprisingly, model guidance was in some disagreement regarding this period, before honing in an an overall idea. Real-time observations from this morning generally support the previous forecast, with only minor changes needed. The main change with this final update was to tighten the snowfall gradient across Central Illinois, where over a very short distance snowfall totals may range from a dusting to a couple of inches.
Precipitation has started to spread into Southwest and Southern Illinois this morning. This activity will steadily spread across the rest of the state through early to mid afternoon. This activity will then continue from this afternoon into tonight, before ending Thursday morning for most areas. Precipitation will be all snow across Northern and Central Illinois, though some mixed precipitation may be possible along the snow/rain line in Central Illinois. Periods of moderate to heavy snow will be possible at times this afternoon into early tonight, across portions of Northern and Central Illinois...Otherwise generally light snow is expected across Northern and Central Illinois during most of this event. Temperatures and snowfall ratios will start off on the marginal end into this evening, before growing more favorable tonight into Thursday. It should be noted that across Southern Illinois, precipitation looks to stay predominately rain, with just a chance of isolated backside snow showers late tonight or early Thursday morning.
Below are visuals of estimated start and end times of precipitation for this event.
Final snowfall totals in an axis across the heart of the state will be in the 2-5" range, with amounts tapering lower on either side of this main axis. There will be a very sharp gradient on the southern end of the main axis, across Central Illinois.
Below is the snowfall forecast for this event.
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