Powerful northwest steering winds at jet stream levels aloft—between 10,000 and 40,000 ft.—have delivered a healthy early autumn chill to the area with impressive speed over just the past few days. Freezing temperatures predicted overnight across northern Wisconsin and Minnesota were expected to bring the 2007 growing season to an end. A growing season is defined as the period between the last freezing temp of spring and the first 32° reading of autumn.
While hardly chilly enough to support frost, Chicagoans haven’t escaped the cool air either. Area residents find daybreak temperatures flirting with the 1955 record low of 44°. Readings are to recover a bit to 65° beneath Wednesday’s sunny skies. But, that reading is cool for the season, 10° below normal.
Cool as it is now, highs hold to the low 60s Saturday after near record daybreak lows around 40°. The weekend is to be this area’s chilliest since mid-April.
--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.
