Tuesday's 80s are long gone, as absent as the sunshine and southwest winds that helped propel city highs to 83 degrees at O'Hare International Airport and the lakefront and 82-degrees at Midway Airport. A southward moving, wind-shifting cool front that ignited thundery downpours Tuesday across sections of southern Wisconsin, including the Milwaukee area, is to stall south of Chicago and hold there the remainder of the workweek. Winds converge along such a front producing a pileup of moist air that is forced to ascend and cool. Waves of showers and embedded thunderstorm erupt in this environment with some regularity and threaten in coming days to produce multiple deluges across a narrow swath of terrain from Iowa across northern and central Illinois and Indiana. The recurrent nature of these rains in combination with light winds steering the storms aloft and an atmosphere dripping with 1.50 to 2 inches of evaporated moisture just south of the front raises the specter of additional slow moving downpour-generating thunderstorms capable of some impressive rain totals.
What happened Tuesday in Wisconsin illustrates what can take place in this type of atmospheric setup. Thunderstorms swamped River Falls with 2.45 inches while unleashing 1.30 inches on sections of Milwaukee and 1.00 in north suburban Port Washington.
Three day rain projections for the Chicago area vary widely among the 20 most recent computer estimates generated by a suite of forecast models Tuesday ---they range from as little to 0.52 to as much as 2.98 inches.
The return of clouds and the prospect they will dominate the next three days has been a common theme this summer. Since June 1, Chicago has received just 55 percent of its possible sunshine---far less than the 67 percent considered normal---and enough to make the summer season to date Chicago's cloudiest in the 17 years since 1992.
What happened Tuesday in Wisconsin illustrates what can take place in this type of atmospheric setup. Thunderstorms swamped River Falls with 2.45 inches while unleashing 1.30 inches on sections of Milwaukee and 1.00 in north suburban Port Washington.
Three day rain projections for the Chicago area vary widely among the 20 most recent computer estimates generated by a suite of forecast models Tuesday ---they range from as little to 0.52 to as much as 2.98 inches.
The return of clouds and the prospect they will dominate the next three days has been a common theme this summer. Since June 1, Chicago has received just 55 percent of its possible sunshine---far less than the 67 percent considered normal---and enough to make the summer season to date Chicago's cloudiest in the 17 years since 1992.
