Chicago’s back in hot, humid tropical air Wednesday and on the precipice of the area’s fifth 90(degrees) high of 2006. But, areas downstate will really broil with mid to upper 90(degrees) highs combining with Gulf Coast-level humidities to produce a second day of triple-digit heat indexes.
St. Louis is headed for 98(degrees) Wednesday afternoon. Low 90s aren’t out of the question in sections of the Chicago area, where rain-cooled thunderstorm “outflows” are likely to produce impressive temperature gyrations as the storms swing across the region. Hot air is exceptionally buoyant–i.e. inclined to ascend through the atmosphere, cooling and condensing as it does–and is therefore an important ingredient in generating the mammoth clouds which parent thunderstorms.
Tuesday heat indexes in southern Illinois peaked at 104(degrees) at Fairfield and 102(degrees) at Mt. Vernon, Centralia and Carbondale.
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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.
