Arctic chill cuts into snow totals outside lake snowbelt
Bitterly cold air grips Chicago Tuesday. The gusty winds which greet area residents this morning have delivered a reinforcing blast of frigid air which is to slash peak readings to the upper teens Tuesday while limiting wind chills to -6 to +6°. Flurries will fall a fourth consecutive day while stacking up impressively in the same SW Michigan/north-central Indiana areas hit so hard by lake snow over the weekend. 6-12" totals are possible there. But, while the winter snowpack is flourishing there, cold air’s skimpy moisture content is only to support flurries here-and light fluffy ones at that. Cold air impacts the crystallization process by which snowflakes form. The irony is that while frigid air holds a fraction of the moisture of warmer air, snowflakes are often larger. That’s why Midway Airport received 0.5" of snow Monday and Berwyn was home to a 0.8" accumulation—five to eight times the snowfall which typically occurs with the 0.01" water content in Monday’s snow.
--By Tom Skilling, WGN-TV Chief Meteorologist