Upper Midwesterners may have to join their Canadian neighbors in western Ontario Province in shoveling snow over coming days. Two exceptionally powerful jet streams-one roaring south from the North Pole, the other draped from the Pacific to the East Coast–are in the process of phasing (combining) Wednesday morning. The situation has explosive atmospheric consequences. With arctic air being injected into the wet storm responsible for rain in Chicago as the day gets underway, the temperature spread across the system will grow more extreme causing air pressures to drop, wind velocities to increase and the storm’s precipitation shield to grow heavier and more widespread. The system’s strengthening winds will whisk unseasonably cold air much farther south than might otherwise be expected this time of year and a foot or more of snow may fall in northeast Minnesota. Of interest will be the reaction as unseasonably cold air makes contact with the warm Great Lakes. Thundery squalls with mixed precipitation may result.
Sources: NOAA-NCEP, NWS Chicago archives
WGN-TV/Thomas Valle, Brent Gilles and Zach Rodeghero
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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.
