WINTER STORM UPDATE
ICY CONDITIONS EXPECTED TO DEVELOP THIS AFTERNOON AND EVENING ESPECIALLY IN AREAS NORTH AND WEST OF THE CITY
Cloudiness has been thickening and lowering across the Chicago area this morning as the winter storm approaches. Temperatures have also been on the increase, rising into the middle and upper 20s by mid-morning. However dew points remain low, ranging from the single digits to the teens across the metropolitan area.
Radar returns are increasing as a strong southwesterly flow brings a slug of moisture into the area, but due to the initial dryness of the atmosphere it will take several more hours for it to moisten to saturation and allow the precipitation forming in the clouds to reach the ground.
Morning upper-air reports show warm air moving in aloft, so the precipitation here is likely to fall as sleet and freezing rain instead of snow. At the 5,000-foot level, temperatures are already near or above freezing with the warming continuing, Preciptation has begun in Iowa and Missouri with most locations reporting sleet and/or freezing rain.
We expect precpitation to move into the Chicago area from the southwest during the afternoon. There may be a brief flurry of snow at the onset, but that should quickly transition into sleet and freezing rain.
The most critical time for icing conditions should be from about 3 to 9 p.m. Temperatures should continue to rise slowly, though readings may drop back a few degrees when preciptation begins due to cooling from evaporation. Areas in the city and close to the lake should experience the least amount of icing as warmer air moves in from Lake Michigan with the most serious icing expected west and north of the city.
Readings should climb above freezing early tonight, allowing the the ice and glaze to melt. By Sunday temperatures could be approaching the 50-degree mark. Temperatures will crash in the storm's wake Sunday afternoon with a period of snow flurries expected.
Updates will be posted as necessary this afternoon and evening.
--By Steve Kahn, WGN-TV Weather Center Meteorologist