Chicago’s veteran Midway weather observer, Frank Wachowski measured 100% sunshine both Thursday and Friday—the first time this has occurred back to back here since last November 4-6, right after the Cubs won the World Series. The strong sun helped boost Friday’s high temperatures to 86-degrees at Chicago’s official O’Hare observation site—the highest a 90-degree reading at Kankakee.
With low pressure and the associated cold front far to the north over Lake Superior, temperatures are expected to peak in the upper 80s both Saturday and Sunday, giving us the warmest weekend since last August 27-28. Gusty west to southwest winds will push these very warm temperatures right up to the Lake Michigan shoreline.
An upper-air disturbance may trigger a period of showers and thunderstorms Saturday night. And a band of scattered showers and isolated thunderstorms could precede and accompany the cold front, as it moves south through our area Sunday night and early Monday.
Strong north to northeast winds on the leading edge of cool Canadian-source high pressure will follow the cold front Monday, churning the waters over Lake Michigan and dropping temperatures back into the lower 60s over the city to the lower 70s well inland. This cool high pressure will hold through Tuesday, finally drifting off to the east, allowing the return of warming southerly flow Wednesday.