Another Warm Month Finishes Chilly

Posted: November 8, 2017, 6:44 pm by ccastellano

With the recent cold and snow in early November, it certainly seems like summer-like weather has been gone a long time, doesn’t it? However, very warm weather that dominated the final half of September persisted through a good chunk of October. Circumstances changed significantly to close out the month and although severe weather was not particularly notable, active weather did highlight the period at times.

Wherever we can get warmer weather we certainly will take it, especially getting closer and closer to the winter season. This was the case to start October, as the momentum from the record-breaking warmth that ended September ran into the start of the month. Though many reached daytime highs in the 70s and 80s, the warmest weather of all major cities was enjoyed in Columbus where the first week saw highs of 83 degrees on the 3rd, 86 on the 4th, and 85 on the 7th. In fact, from the 1st through the 23r the warmth dominated, and many Midwest cities climbed into the top-10 warmest on record for the period. While this portion of October averages in the middle and upper 60s, the 2017 version was well into the lower and middle 70s, a departure of 6 to 8 degrees above the mean.

This changed drastically on the heels of a potent storm system that dragged a cold front through the area on the 22nd. Low pressure associated with this front became a strong, deepening cyclone over northern Michigan. The resulting northwest winds filtered in a deep, cold airmass that was significant enough to keep it cool the remainder of the month. In fact, in the case of Indianapolis, the last 8 days broke the record for the coldest of the particular stretch, with average highs at 48.3 degrees, an amazing 12.8 degrees below normal! 

Rewinding back to the warm side of the month, the Chicago area certainly endured some heavy rainfall. This was the result of a frontal boundary that stalled over the area on the 13th, which at first, only produced showers. However, as low pressure rode along the front and pushed into Wisconsin, rainfall became enhanced and trained over Chicago Metro and remainder of northern Illinois. It resulted in an all-day rain event, with heavy enough rates to result in flooding. Total daytime rainfall of 4.19" for the 14th was a new record for O’Hare, smashing the previous high mark of 1.15” in 2003. Rockford’s 24-hour rainfall also broke their old record, with 1.80” (0.97” in 1966).

October overall was a normal month for precipitation outside of this major event. Taking out the big surplus over Northern Illinois, the rest of the Midwest held within their typical means for rainfall or just slightly above, keeping any mention of drought firmly in check.

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