A major, slow-moving, long-duration and disruptive winter storm is set to impact over 90 million people across 19 states spread over 2,000 miles, bringing the potential for significant snow accumulations to Northern Illinois in two back-to-back snow systems beginning this evening.
Round One: Tuesday afternoon through Wednesday evening
Precipitation is expected to begin around 2-4 pm this afternoon, primarily as rain before switching over to snow after sunset, continuing throughout Wednesday evening with steady snow rates of 0.5-0.75″ per hour. The heaviest snow is expected to fall between 3 am and Noon Thursday, with rates closer to 1″ per hour.
One feature of this storm will be sharp cutoffs, leaving a wide range of snow totals from one location to another, even within a short distance. At this time, it appears northern areas, such as Rockford and Lake County, may receive only around 2″, while southern sections, especially south and east of I-55, will receive the heaviest snow in the immediate Chicago area, with 5-11″ predicted. Areas south of Kankakee and throughout central Illinois look increasingly likely to pick up more than a foot of snow. Even a minor shift in the storm`s track could bring the higher amounts further north or south, but these totals show the general range of snow accumulations expected.
The National Weather Service has issued a Winter Storm Warning for Southern Cook County, including Chicago, DuPage and counties to the south and southwest, and Northwest Indiana. A Winter Weather Advisory is in effect for Northern Cook, DuPage, Kane, DeKalb and Lee Counties in Illinois. Both the Warning and Advisory are in effect from 8 pm Tuesday evening through 6 pm Wednesday.
Round Two: Thursday
Snow picks up again Midnight Thursday through mid-afternoon and once again will favor southern sections, though the latest forecast models show the entire system shifting further south, which may decrease Thursday`s totals. For now, 1-2″ is forecast for most of the Chicago area and 2-4″ along and south of I-80. There is also an increasing chance for lake-effect snow to form Thursday, bringing potentially higher totals to areas nearest Lake Michigan.
As always, our hardworking crews will be out in force. Watch for additional updates from the Arctic Storm Center through Thursday night, when any lingering snow finally ceases.