It’s hard to imagine only days after bidding one of the hottest air masses here in 11 years adieu that Summer 2006 could possibly be averaging cooler than a year ago. But, it’s true. Temperatures since June 1 are running 2.2 degrees behind last year. And, while the set of 90°-plus highs predicted Saturday and Sunday are to produce the Chicago area’s third warmest weekend of the 10 since the season began, the city’s official tally of fifteen 90s lags behind last year’s 19 to date.
Friday’s 28 percent late-day relative humidity underscored the dramatic decline in atmospheric moisture of the past two days. The once oppressive tropical rain forest-like 76° dew point midweek had yielded to dry 48° dew point air. To the eye, the area’s haze-shrouded midweek horizons were sharply defined Friday. Humidities went into an afternoon free-fall as air heated by strong August sunshine ascended, tugging cooler air off Lake Michigan and encouraging dry air aloft to sink to the ground.
--By Tom Skilling, WGN-TV Meteorologist
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
