Showers and thunderstorms are expected this afternoon under the influence of a large
low pressure area east of Lake Huron in Canada's Ontario province. Steered by a strong
northerly jet stream flow aloft, cool high pressure will drift south and east out of
central Canada and hold over the Midwest through Tuesday. This will give northern
Illinois temperatures about 5 degrees below normal for the next few days. After today's
rains, a brief dry period will hopefully allow most of the area's swollen rivers and
streams to slowly fall.
WARMER, MORE HUMID AIR BY MIDWEEK
By Wednesday, the upper air pattern will change significantly with a west-to-east jet
stream flow establishing along the United States-Canada border. This will block the
southward movement of cooler Canadian air masses, and allow a gradual intrusion of
warmer, more humid air from the central and southern Plains into the Midwest. During
the last half of the week, Chicagoans should see readings average about 5 degrees
above normal along with much more humid conditions and frequent showers and
thunderstorms. Rainfall totals the latter half of the week could easily exceed an inch.
--By Paul Dailey, WGN Weather Center Meteorologist
