A potent early spring snowstorm is poised to impact portions of Northern and Central IL Friday evening into the day on Saturday. This system has all the makings of a significant late winter snowstorm, with high moisture content, strong frontogenical forcing and gusty winds. The low pressure will be taking shape over the next 24 hours across the western plains. The surface low will begin to move southeast during the day on Friday and should be near STL by around midnight Friday. The exact track of this low pressure will determine where exactly a narrow yet heavy swath of snow will fall across IL. It currently looks to be along and north of I-74 with. The map below details forecast snowfall amounts for the northern half of IL. While there is still time for some track adjustments, this corridor is likely the safest bet for significant accumulating snows.
The snow will likely begin late Friday evening between 8-10 pm across far NW IL. The snow should push east across the remainder of IL overnight Friday. The southern extent of the snowfall is questionable at this juncture. It currently appears that rain may change over to very wet snow even a little south of I-74 during the day Saturday, with more of a mix of rain and snow south of that region but north of I-72. Precipitation will end from west to east early Saturday afternoon with precip lingering across far eastern Central IL into the late afternoon. Within the zone of heaviest snowfall, rates may reach 1-2” an hour and with gusty winds, travel will be difficult, especially early Saturday morning. Cannot rule out some sporadic power outages in the zone of heaviest snowfall with very heavy wet snow and gusty winds. This may cause some tree branches to break and fall on power lines. This is also a perfect example of “heart attack” snow, given the extremely heavy and wet nature it can be very dangerous to shovel, so be sure not to over exert yourself!