CHICAGO — We have fairly healthy rains including some thunderstorms on the way that will arrive in Chicago Friday into Friday night.
Model estimates on potential rainfall range widely from 0.25″ to as much as 2.48″, with the latest average among the 22 members of the Weather Service’s SREF (Short Range Ensemble model) model centered on O’Hare at 1.11″.
There’s a tropical connection with the system behind these downpours and it involves remnant energy from Pacific Hurricane Rosa, whose rains have broken records in recent days in the desert Southwest.
You can see that energy as a jet stream speed max over Colorado, which combines with a generous injection of Gulf moisture to set the stage for Chicago’s upcoming downpours.
Friday into Friday night may well be quite wet at times here in Chicago, with rains likely to arrive in “waves” or “clusters”. Model measurable rain probabilities are 76 percent Friday and 72 percent Friday night. Beneath the wet disturbance’s northern flank, there’s even sticking snow predicted with this system over the northern plains and sections of the Upper Midwest! Winter weather advisories are out in North Dakota and sections of Wyoming and Montana.
For a little history on the origins of the incoming rains, check out this satellite-sensed precipitable water animation of Rosa put together by Scott Bachmeier of CIMSS at the University of Wisconsin-Madison, which tracks Rosa as it spins up off the Mexican coast, then sweeps northward into the Southwest U.S., where it has produced flooding and record October rains the past few days.
Some of Rosa’s remnant energy at jet stream level, joined by an incoming supply of tropical moisture off the Gulf of Mexico, will contribute to rains headed for Chicago tomorrow into Saturday.
The Chicago area and surrounding areas of northern Illinois and southern Wisconsin are outlooked for potentially excessive rainfall by the National Weather Service’s Weather Prediction Center (WPC) at NOAA’s National Center for Weather and Climate Prediction in Maryland.
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