A new round of showers/t

by: Tom Skilling, WGN-TV Weather Team

Posted: Jul 7, 2023 / 02:05 AM CDT

Updated: Jul 7, 2023 / 09:16 AM CDT

The respite from the rains in recent days—for some portion of the Chicago area, from flooding downpours—-is to continue as Friday dawns. But already, the next rain-making system is taking shape in the Rockies and Plains. Its clouds will be spreading across area skies Friday with an overcast assembling during the afternoon and a scattering of showers already putting in an appearance over a portion of the Chicago area as evening comes on.

Though UNLIKELY to produce the gargantuan rain accumulations which led to flooding over a swath of the Greater Chicago area Sunday and again this past Wednesday, it would appear that some locally heavy thundery downpours are to be ours. An in-house review of range of model solutions–the best way to assess the potential range in rainfalls a given weather situation is to produce—suggests we could see totals ranging from 0.20″ to as much as 1.40″. That’s quite a spread, but that’s the way summer rains occur. They’re varied–often wildly–in part because of involvement of t-storms which can produce such concentrated downpours which unleash their rains intensely on one area while areas relatively close-by see substantially less.

Satellite and radar imagery tracked fast erupting showers and t-storms over the northern Rockies and western Plains late Thursday. Cooling aloft acted to “destabilize” the atmosphere. As the temps cool aloft over a mass of warm, relatively humid at the surface, air at the bottom of the atmosphere is encouraged to rise—it becomes “buoyant” and it continues to rise as temps around it cool. It’s this process, with some help from the large scale lift produced by pockets of strong winds in the jet stream, that put together the showers an t-storms we so often experience.

With July’s rainfall already running at more than 6 times normal in the month’s opening days, it’s hard t see up breaking out of this pattern. Two more potentially active rain/t-storm producing systems appear a good bet next week–one later Tuesday spilling over into Wednesday and Wed night; a second likely to sweep in Friday into early next Saturday if current modeling trends verify. As always with summer rains, amounts may vary widely across the area.. We’ve seen that in the Sunday & Wednesday rains earlier this week.

You can see the dust on the weather satellite image.

Here’s a link to a current TRUE COLOR GOES EAST weather satellite animation on which the hazy layer of dust is visible: https://col.st/qq9vJ

THERE’S BEEN A GREAT DEAL OF STUDY, STUDIES WHICH ARE ONGOING, ON THE IMPACTS OF SAHARAN DUST: https://www.aoml.noaa.gov/saharan-air-layer/

FROM CIMSS (the Cooperative Institute for Meteorological Satellite Studies) at the University of Wisconsin-Madison comes this 5-day animation of Saharan dust: https://tropic.ssec.wisc.edu/…/movies/goes16split.html

Check out some of the coverage of the Saharan dust showing up in Southern U.S. media:

—https://www.kvue.com/…/269-99a00659-83d3-434b-9ca6…

—https://www.firstcoastnews.com/…/77-ad5b6628-08fe-47a8…

—https://www.kut.org/…/saharan-dust-is-making-its-way-to…

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Scientists have established Saharan dust’s role in providing nutrients the Amazon region of South American thousands of miles away:

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