Season's biggest snow puts brakes on rush hour

Snow fell steadily for nearly 10 hours Tuesday, producing the season's heaviest official
snowfall tally to date. By late evening, totals were approaching 5 inches at O'Hare,
solidifying the 2008-09 season as one of the 13 snowiest at this early point in 124 years of
weather records. The ill-timed snow crippled Tuesday evening's rush hour, producing
inflated travel times reminiscent of the infamous 1990 Valentine's Day rush-hour storm. Its
9.7-inch tally was nearly twice Tuesday's snowfall, yet each induced gridlock on area
thoroughfares, hampering snow removal.
The cold temperatures Tuesday turned the 0.30 of an inch of precipitation (water
equivalent) into a volume of snow nearly twice that which might have been expected in a warmer
environment. Snow formation is especially efficient at low temperatures which leads to
bigger flakes.
CONCERN GROWS OVER NEXT SYSTEM
An even more potent storm appears to be taking aim at the Midwest Thursday night into
Friday. The Chicago area is to be positioned precariously close to the boundary between ice
and snow in a storm predicted to produce as much four times the precipitation of
Tuesday's disturbance.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune