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WEATHER REPORT: TOM SKILLING 7-DAY FORECAST WGN-TV WEATHER CENTER

Severe weather/flood producing boundary moves east

January 09, 2008|By Tom Skilling

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It's now moved east, but the combination of very cold air aloft and warm moist flow below separated only by a narrow transition zone (frontal boundary) produced a line of severe storms and heavy rain-producing thunderstorms from Oklahoma to Lower Michigan. For northeast Illinois and northwest Indiana, first it was severe t-storms and tornadoes on Monday, then flood-producing heavy rains later Monday and early Tuesday.

'Unstable' conditions spawn severe weather

The frontal boundary is a transition zone between the cold sinking air and the warm moist rising air creating very unstable conditions where severe t-storms and heavy rain develop.

Waves of t-storms

"Training" of t-storms over the same areas ahead of a nearly stationary frontal system results in 3-5" rain totals and subsequent flooding.

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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.