Warm surge blows in, along with fog, drizzle

Friday marks the 32nd consecutive day Chicago-area residents have looked at snow covered
ground. It's the longest stretch of snow cover here in 8 years -- and one which is about
to end. Dramatic warming, which sent Plains temperatures as far north as Nebraska
soaring into the 60s on Thursday, is making its move on Chicago. Modest warming sent highs here
to 25 degrees Thursday -- up from 17 the day before. Readings jump another 15 degrees
Friday to 40. But, it's Friday night and Saturday that the most substantial warming is to
get under way. South winds from the Gulf of Mexico increase by Saturday morning to 80
m.p.h at 3,000 feet above the ground here. The set-up is to generate 30+ m.p.h. surface gusts
by late Friday night. As moist air reaches the metro area late Friday the lower
atmosphere will become saturated. Clouds, fog and drizzle will develop quickly. With dew points
-- the temperature at which the humidity is 100 percent -- predicted to rise into the low
40s over the cold, snow-covered surface during the night, the potential for thick fog is
real.
The rapid warming threatens ice jams on area rivers as the run-off from melting snow
hits. It's a formula for river flooding.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune