Dry, comparatively warm weather dominates the vast majority of this final weekend of
summer. But, the atmosphere is hardly moisture free. Nearly an inch of evaporated water
hangs in the air over Chicago both Saturday and Sunday. Daytime heating is to increase
the rate at which temperatures decline with height. It’s a situation referred to as an
unstable atmosphere, and it encourages air to rise. With an inland-moving lake breeze
likely to slice into the moderately moist air, it’s not inconceivable a few isolated t-storms
may form. The same process repeats Sunday, but strengthening northeast winds may
force any isolated showers to drift inland to the west or south suburbs in the afternoon.
Rainfall coverage is to be limited.
SIX OF SEPTEMBER 2007’S FINAL 10 DAYS SURGED PAST 80 DEGREES
To date, Chicago has had only three days in the 80s this month, versus 11 a year ago.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune
