Were tropical storms responsible for last September’s heat wave?

Dear Tom,

You said that “Alberto” was partially responsible for our recent heat. Wasn’t there a similar scenario for last September’s heat wave.

Thanks,
Brian Beecher

Dear Brian,

You are correct. Last September, the Chicago area was hit by late-season heat that set seven straight record highs in the lower and middle 90s from September 20-26, while hurricanes Jose and Maria were moving north along the Atlantic Seaboard. The effect of tropical systems moving north in the Gulf of Mexico or along the East Coast are twofold in bringing heat to the central and eastern U.S. Air venting out of the top of these storms compresses and warms as it subsides, leading to higher surface temperatures. In addition, the north-bound storms slow the eastward progression of weather systems holding cold fronts, that would normally move through Chicago, at bay.