FEATURE GRAPHIC: April 2009 Archives

Chicago's warmest weather to date in 2009—and the area's warmest weekend in more
than six months--is on the way. The warming cycle, likely to extend through the
weekend, began with Wednesday’s 61-degree high and builds Thursday with the
predicted 74-degree high. Southeast winds will slice ashore off Lake Michigan limiting
shoreline readings to the low and mid-60s. Lake cooling will be extinguished Friday
and Saturday by powerhouse south/southwest winds gusting at times to 40 m.p.h. and
being driven by falling pressures as a significant large-scale spring storm develops
over the nation's midsection this weekend and early next week.

Chicago's meteorological wild card this weekend revolves around the potential for
thunderstorms—principally Saturday evening and in areas north toward the Wisconsin
line. The outflow from these storms may provoke several additional thunderstorms as
far south as the Chicago area Saturday night and early Sunday. A more substantial rain
risk arrives with thunderstorm clusters later Sunday night and Monday. This period
could include the area’s first organized severe weather outbreak of 2009. A suite of
computer projections hints a corridor from Texas and Oklahoma northeastward into
northern Illinois and Wisconsin may be in for 1 to 4 inches of rain the next 5
days--heaviest just west of the Chicago area.

More than half of years have seen an 80-degree reading by now

April 20 has been the average date of Chicago's first 80 degree or higher temperature
the past 11 years--and weather records at Midway Airport reveal more than half of the
past 81 years there (since 1928) have hosted an 80 by this date.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

NOTE: In the bar graph of Chicago's daily high and low temperatures of April 1938, the black bars represent the normal days.
Steve Kahn WGN-TV/Chicago Tribune Meteorologist

It's hard to believe that Chicago's persistent cold, wet spring could take a turn for the
worse, but that is exactly what is expected to take place today. Chicagoans will be
greeted by a cold rain this morning, but farther north and west, conditions become
increasingly wintry. On Saturday night, blizzard conditions existed over Nebraska,
western Iowa and southern Minnesota, with up to 9 inches of snow forecast for portions
of eastern Iowa and southwest Wisconsin. Lesser amounts of snow were spreading east
across northwest Illinois and southeastern Wisconsin.

Chicago's changeover from rain/sleet to snow should be delayed until Sunday evening
because of strong northeast winds off the 40-degree Lake Michigan waters. As the
storm center moves east through Illinois into Indiana, cold Canadian air will flow into
northern Illinois on the storm's backside, forcing a complete changeover from rain to
wet snow. By Monday morning, accumulations could range from 6 inches north along
the Illinois-Wisconsin border to a couple of inches in Chicago's southern suburbs.
Depending on temperatures, snowfall totals could vary widely as storm total liquid
precipitation could run up to an inch, especially in areas where thunder occurs.