SWOP Weekly Weather Discussion

HEADLINE

Typical summertime heat and humidity is expected this weekend...followed by increasing rain chances by early next week.

DISCUSSION

A prominent upper-level ridge of high pressure centered over the Desert Southwest into the Southern Plains will build northeastward into the Ohio River Valley over the next couple of days...resulting in high temperatures climbing into the lower 90s from Friday, August 8th through Sunday, August 10th. Meanwhile a trough of low pressure over the Pacific Northwest will track eastward and gradually suppress the building ridge. This will push a slow-moving cold front southward toward central Illinois over the weekend. As the front becomes parallel with the upper flow, it will stall from Michigan to Iowa...with scattered thunderstorms possible along and northwest of the I-55 corridor for both Saturday and Sunday.

Additional short-wave energy dropping out of Canada will nudge the boundary a bit further southward by early next week, resulting in increasing rain chances across all of central and southeast Illinois from Monday, August 11th through Wednesday, August 13th. After that, all medium range models suggest the upper ridge will once again build back northward into the Midwest by the end of next week. This will likely lead to a decrease in rain chances and boost temperatures back into the lower to middle 90s.

The latest 6-10 day outlooks (Aug 13-17) from the Climate Prediction Center (CPC) suggest ABOVE normal temperatures and ABOVE normal precipitation across central Illinois.

Issued: 8/7/25