A potent weather situation threatens to come together Wednesday afternoon and
evening -- one which threatens downpours and lightning-generating thunderstorms
accompanied at some locations by potentially powerful wind gusts. NOAA's Storm
Prediction Center has Chicago and surrounding areas of the Midwest outlooked for
possible severe weather. A cold front crashing southward on powerful northwest
jet-stream winds sweeps into humid, near-90-degree air -- an environment in which
atmospheric levels soar. It's this energy which powers t-storm winds and with nearly 2
inches of water evaporated in the atmosphere, the specter of local rainfalls of 1-3
inches isn't out the question in the hardest hit sections. It confirms a climatological
trend that has been observed in many Julys. Measurable rains become less frequent this
time of year -- occurring an average of 9 times per month. But the rains that fall can
be much heavier -- producing quick 1-2 inch tallies.
71% OF CHICAGO 90+-DEGREE DAYS OCCUR BEYOND THIS DATE
While hot weather's been in scarce supply this year, the area has typically recorded 7 of
the 24 days of 90-degree temps by July 2. That means summer is only getting going
with 71 percent of the areas's 90s to come.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune
