A second band of lake effect snow is passing over Cook and Lake County Tuesday morning.
The snow system is expected to move through and then the lake effect snow machine is expected to take over later Tuesday.
The warning remains in effect until 1 a.m. Wednesday morning for Lake County in IN and from 9 p.m. Tuesday until 9 a.m. Wednesday for Porter County in Indiana.
Lake-effect snow, a relatively rare occurrence in Chicago, is providing the city with its biggest snow event of the season to date.More news: Rate hikes: GCC braces for higher cost of funds and currency appreciation
More news: Secret Service nabs intruder at White House entrance
More news: Trump Middle East Advisor Talks Peace with Leadership in Israel
Portions of Lake and Porter counties are likely to see four to eight inches of snow. Allow extra commute time this morning, and drive with extreme caution. "Typically, these sort of lake effect bands are only 10 to 15 miles wide but can produce very heavy snow, sometimes in excess of 2 inches per hour", the warning reads. Visibilities vary greatly and can drop to zero within minutes.
The Chicago area could see its largest snowfall since before Christmas, with several inches of snow expected Monday. The wind has been NNE, so the wind off the lake has been bringing the lake-effect bands in SE Wisconsin, NE Illinois and also off Lake Huron into E. MI.
Significant snow risk and limited excessive cold risk are the weather hazards expected for Tuesday.