Chicagoans have watched the number of truly cold winter days plummet over the past two and a half decades. By the latter half of the 1990s, temps lower than single-digits were occurring at less than half the pace of the late 1970s–plunging from 34 per cold season to just 15. That’s no doubt one reason the late arrival of frigid arctic air this season, the type of intense chill that numbs the skin, has occurred with so little fanfare. The metro area is now two weeks beyond the historic first date for a sub-freezing daytime high (Nov. 25)–and none is in sight until, perhaps, next week. Wednesday promises a fourth consecutive day above 40(degrees). But not all sections of North America are as lucky. A stunning 120(degrees) north-to-south temp spread has developed on the continent. And Chicagoans may be surprised to learn sub-zero temps hovered only 700 miles to the northwest Tuesday. Though 70s reached north to Virginia–readings 25(degrees) above normal–Canadians were dealing with heart-stopping -40(degrees) daytime temps in the country’s northern territories–levels 50(degrees) below normal. Forecasters are monitoring the jet stream for signs of any buckling in coming weeks. Such “waviness” would initiate a southward cascade of bitter arctic air. Computer forecasts focus on three potential “cold” periods in the next two weeks. The first, and most modest of the three, arrives Friday. More important cold air next Monday and still colder air hits toward Dec. 20.
Sources: NWS Chicago temp/precip archives, various NWS forecast offices, NOAA-NCEP various supercomputer forecast models
WGN-TV/Thomas Valle
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
