Sunny start to workweek; storm hits Tuesday

High pressure holds over Chicago today; but as it moves east Tuesday, winds strengthen
from the south and clouds increase rapidly from the west. Meanwhile, low pressure will
produce heavy snow in the southern Rockies then move into the central Plains on Tuesday.
That system is projected to intensify as the center of lowest pressure tracks through
northern Illinois on Wednesday. As a result, Chicago's temperatures will rise, probably warming
into the 40s despite the thickening and lowering cloud cover. Rain could begin Tuesday
afternoon, possibly becoming heavy at times as showers -- maybe thunder -- develop Tuesday
night and Wednesday morning. Wednesday looks to be very stormy from the Great Lakes to
the Gulf of Mexico, with heavy snow in Wisconsin and severe storms south of the Ohio
River. Chicago will experience falling afternoon temperatures as rain changes to wet, sticking
snow.
MUCH COLDER AFTER WEDNESDAY
Chicago temperatures will stay below freezing Thursday to Sunday as cold Canadian-source
high pressure is reinforced after a second snow-producing low pressure Friday.
--By Paul Dailey, WGN Weather Center Meteorologist