Thursday forecast: Morning showers clear Chicagoland, then cold front moves in later

Chicagoland woke up to cloudy skies and scattered showers Thursday morning, but the rainfall remained light.

Those showers will clear the area and become more and more scattered into the late-morning hours, with high temperatures reaching the mid-70s on Thursday afternoon ahead of a cold front that will move through the area.

The cold front will bring a slight chance of showers or an isolated storm, but the main noticeable change in conditions will be gusty north/northeast winds that will create a high swim risk at Lake Michigan beaches and bring fall-like temps by Friday, with highs only in the upper 60s.

Things look to warm up after that, however, with Labor Day weekend shaping up to be sunny and pleasant (see more below).

Thursday: Temperatures and winds  

Highs will peak in the mid-70s across the area Thursday afternoon, but readings will settle back down into the 60s rather quickly by evening, as winds shift from the southwest to west, then northeast down the length of Lake Michigan by evening.

The gusty north/northeast winds will produce a dangerous 4- to 7-foot chop and life-threatening currents on Lake Michigan late Thursday into Friday.

A Beach Hazards Statement is in effect for all of Chicagoland’s lakeside counties through Friday afternoon.   

Thursday: Sunburn forecast

Quiet weather settles in following Thursday’s scattered showers and possible thunderstorms. No additional rainfall is expected through the long holiday weekend.

Forecast highs, how far from normal

Readings bottom out on Friday, when highs are only likely to reach the upper 60s, a level nearly 15 degrees below normal and more typical of early October. Slow moderation is expected as we proceed through the upcoming weekend, with plenty of sunshine and temps closer to normal levels.

500-millibar upper air pattern

Strong ridging moves from western to central Canada, leaving the door wide open for cooler air out of Canada to plunge into the eastern and central U.S., and it’s showing signs of staying power.

This is quite the sequence of negative height anomaly (troughs with plunges of chilly air) over the Midwest, leading to well below normal temperatures overall for the first two weeks of September. This type of pattern in winter would result in brutally cold temperatures.   

Forecast average temperature anomaly: Aug. 27-Sept. 2

Much below normal temperature trend for the final days of August and the opening two days of September from the central U.S. to the Great Lakes and Northeast.

Forecast average temperature anomaly: Sept. 3-9

Cooler than normal weather pattern locked into place beyond the opening week of September for much of the Lower 48, with the lone exception across the Pacific Northwest, where summer-level heat hangs on.