Sat-Sun, Jan 30-31st Winter Storm Update #5

(11:45AM - 1/30/20) A winter storm will be impacting the state and region, today through Sunday. This winter storm is expected to bring a significant snowfall, with several inches of accumulation expected across portions of the state.

Summary...
A winter storm is expected to impact the state and region today through Sunday, and is expected to bring a significant snowfall with several inches of accumulation to portions of the state. The storm system ejected out into the Plains last night into this morning. The storm system is expected to move eastward through the Mid-Mississippi Valley today, and eventually through the Ohio Valley on Sunday as it weakens. Model guidance has been and continues to be in overall good agreement regarding this event, with real time observations generally supporting. With this update we have expanded the heaviest snowfall corridor of 6-9" as model guidance has stayed consistent in showing higher amounts, and confidence has grown. Additionally, the gradient across Central Illinois was adjusted and tightened to account for the latest trends.

​Forecast...
Northern Illinois: 
Precipitation is expected to spread into Northern Illinois this afternoon. While portions of Northwest and North-Central Illinois may start as a period of rain or a mix, precipitation will steadily change over to snow as dynamic and evaporative cooling processes occur. Across Northeast Illinois, precipitation will be snow from the onset. Precipitation of  varying intensity will then continue through Sunday evening. The most significant period of snow will be from late this afternoon through early Sunday morning. During this time periods of heavy snow are expected, with high snowfall rates of 1-3" an hour likely at times, as well as the possibility for thundersnow. In addition to the snow, wind gusts of 25-40MPH will be possible, late this afternoon evening through early Sunday morning.

Additionally, lake enhancement is expected across Northeast Illinois during the event, with a small window for lake effect snow on the backside as the storm departs the region.

Central Illinois...
Precipitation has been spreading into Central Illinois late this morning, and will continue to overspread the area through early this afternoon. Precipitation will then continue through Sunday evening. Across Central Illinois for areas south of I-74, much of the precipitation will generally be rain from the onset through Sunday morning. Beyond this time, areas of snow and snow showers are expected Sunday morning into Sunday evening. Across Central Illinois for areas along and north of I-74, this event will be mostly snow, outside of a period of rain or mix at the onset.

Southern Illinois...
Area of rain will first spread into Southern Illinois this morning. Periods of rain will then continue through Sunday morning. A period of mostly dry conditions is possible for a time Sunday morning, before colder air wraps in and snow showers become possible late Sunday morning through early Sunday night.

​What's expected...
A swath of snowfall totals of 6-9" is expected across Northern Illinois, with locally higher amounts possible. There will be a sharp gradient where snowfall totals rapidly taper across Central Illinois. This event is expected to feature lower than average snowfall ratios due to marginal temperatures, meaning it will be a heavy/wet snow.

​Below is the snowfall forecast for this event.

JP