A reinforcing surge of cold air limited Chicago’s high temperature to 35º Tuesday, the third chilliest of autumn to date. The reading extended to six the number of consecutive daytime 30s—the area’s longest late November sub-40º string in 30 years. Arctic air is notoriously dry, a characteristic on display Tuesday. Dew points, a measure of atmospheric moisture, dropped to just -1º at Midway and +2º at O’Hare. Those are readings rarely found outside the arctic, and when they have occurred here, they’ve generally done so in the midst of bitterly cold mid-winter arctic outbreaks. The push of dry air was also reflected in Tuesday’s relative humidity, which plummeted to just 22%—the lowest November level here in 13 years.
Powerful southerly winds interrupt the string of 30s Wednesday. The winds are occurring beneath a 180 m.p.h. jet stream. Wind speeds of 80 m.p.h. just 3,000 ft. above the city will produce surface gusts in excess of 40 m.p.h.
--By Tom Skilling, WGN-TV Chief Meteorologist
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
