Chance of rain in the air for Chicago area

Rain isn't completely out the picture Saturday, but dry hours will
outnumber any wet ones. Saturday afternoon's air is to hold 1.25 inches
of evaporated water and the day's initially light winds are unlikely to
flood the area with cool, stabilizing air off the lake.

With mixed sunshine predicted and a slightly faster than usual vertical
decline in temperature -- a condition which encourages air to rise and
cool, thereby producing clouds -- the potential exists for scattered shower
and thunderstorm development. Computer models are predicting a column of
the atmosphere above Chicago may grow saturated later Saturday with
moisture to an altitude of more than 30,000 feet, suggesting vertical
clouds capable of producing some thunderstorms.
 
Winds converging along a weak southeast-bound front may further
encourage precipitation development, though peak areal coverage isn't
likely to exceed 20 to 30 percent of the metropolitan area.

Lake winds strengthen Sunday, sweeping modestly cooler, drier air across
the area and reducing the chance of rain.