Forces are coming together this evening that threatens to bring a major winter storm to
the Midwest and the Chicago area. A stunningly strong 180 m.p.h. band of jet
stream-level winds is helping generate this intense storm. This is the same system that
brought Las Vegas is biggest snowfall since 1979 and will have copious moisture to
feed it.
This evening radars are beginning to light up with returns as the storm assembles
across the Midwest. Freezing rain has developed in the St. Louis area and is being
reported in the extreme southern portion of the state. Clouds in the Chicago area
should lower and thicken this evening with precipitation expected to begin reaching the
ground in the far southwest portions of the metropolitan area by 7 or 8 p.m. and across
the rest of the area between 9 p.m. and midnight.
Significant accumulations of snow and ice are expected across the Chicago area.
Precipitation is to overspread the Chicago area from southwest to northeast late
tonight—then fall steadily, and at times heavily----through mid-morning Friday.
Strong vertical motion generated by the storm will produce thunder and lightning and
these strong updrafts will produce bursts of heavy precipitation. During thundersnow,
snow accumulation rates can exceed 2 to 3 inches per hour.
The system may seriously impact Friday morning’s rush hour. A cocktail of
precipitation is to affect the area with heavy snow and sleet north of I-80 and snow and
sleet changing to freezing rain and threatening serious ice accumulations to the south
from Pontiac and Kankakee to Rensselaer, Indiana. Local accumulations of around a
foot are possible in counties adjoining the Illinois/Wisconsin line before precipitation
winds down to sporadic flurries or snow showers later Friday morning and
afternoon---tapering off quickly to 1-5” south of I-80.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune
--Steve Kahn, WGN Weather Center Meteorologist
