Update 3:45PM CDT...
The Lake-effect Snow Warning calling for the possibility of 5 to 10-inches of snow due to northeast winds over Lake Michigan developing plumes of snow that will move inland over Lake, Cook and DuPage Counties in Illinois remains in effect until 4PM CDT Tuesday. In Addition the Chicago National Weather Service Forecast Office has also issued a Lake-effect Snow Advisory (light-green-shaded area on the highlighted map) for Will County in Illinois and Lake County in Indiana from 4AM Tuesday until 1AM CDT Wednesday calling for the possibility of 3 to 6-inches additional snow from lake-effect plumes carried by north to northeast winds off of Lake Michigan during that time period. Porter County, Indiana might have to be added to the Advisory Tuesday.
The Warning and Advisory mean there is a strong probability of considerable snowfall during the Tuesday morning commute and possibly the Tuesday afternoon commute as well. A slow-go and hazardous driving conditions will exist Tuesday in these counties and drivers should prepare for long delays and slippery snow-covered roads/highways.
The Chicago National Weather Service Forecast Office has upgraded a Lake-effect Snow Watch into a Lake Effect Snow Warning (dark-green-shaded counties on the highlighted map above) for Lake, Cook and DuPage Counties in Illinois from 7PM CDT this Monday evening until 4PM CDT Tuesday afternoon calling for bands of snow to develop that could eventually amount to over 6-inches of snow in portions of the warned counties.
As winds shift more northeasterly and strengthen, the lake-effect snow will begin this evening, bringing snow plumes off Lake Michigan inland primarily into Lake, Cook and DuPage Counties. With time, actually associated with the deepening Nor’easter low pressure system moving north up the northeast U.S. coastline, winds will become more northerly riding the length of Lake Michigan, steering the lake plumes into northern Will and eventually Lake and Porter Counties in Indiana later Tuesday.
The Winter Weather Advisory for 3 to 6-inches of snow across the Chicago area ends at 1PM CDT this Monday afternoon.
Snowfall totals thus-far have ranged from 1 to 2-inches at many locations to 5-inch-plus totals in Lake County, Illinois. Highest totals reported so far are 5.5-inches at Waukegan and 5.1-inches at Gurnee in Lake County and 4.8-inches at Bull Valley and 4.7-inches at Wonder Lake in McHenry County.