Lake snow builds before a big chill sets in

The meteorologically explosive combination of bitterly cold arctic air interacting with
"warmer" lake waters sets the stage for significant lake snow in portions of the Chicago
area Tuesday and Tuesday night. Moisture-laden air hugging Lake Michigan becomes buoyant
in this environment, fostering snow cloud development. The situation threatens to become
a prolific snow producer as north/northeast winds set up the length of the lake and
channel concentrated snowfall ashore. Snowfall will come and go with increasing frequency as
that band oscillates back and forth across eastern Lake, Cook and Will Counties in
Illinois and Indiana's Lake and Porter Counties. Snowfall is likely to be minimal in the western
suburbs that are out of reach of the lake snow. The potential exists for 2 to 4 inches
of snow, with 6 inches in spots, accumulating Tuesday and Tuesday night near the lake.
The heaviest snows shift into Indiana and continue into Wednesday; the extended duration
could produce 6- to 12-inch totals.
The last time the city saw bare ground was Jan. 5 -- 29 days ago. It's the longest
streak since the 63 days that 1 inch or more covered the ground from Dec. 6, 2000, through
Feb. 6, 2001.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune