The longer the now 12-day old cold spell goes on, the clearer its unusual nature becomes. By 9 a.m. Thursday, Chicagoans will have shivered through sub-zero wind chills 139 consecutive hours. It’s a streak which began at 2 p.m. this past Friday. Meantime, sub-zero thermometer readings greet many metro area residents a 5th consecutive morning Thursday and a 6th appears on its way by daybreak Friday. This places the current sub-zero stretch just shy of the second-longest February record of seven consecutive sub-0 (degrees) readings back in 1979. The record of eight was recorded Feb. 11-18, 1875. A mammoth arctic high extending from the North Pole south to the U. S. Mid-Atlantic and featuring an eyecatching central barometric pressure above 31.18″ of mercury (1056 mb.) over northern Canada later Thursday is behind our big chill. The system has formed as air sinks on a vast scale beneath three converging jet streams.
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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.
