Temperatures befitting a September rather than a mid-November weekend are on the way. Warm weather’s been in remarkably short supply this autumn. Each month since the Sept. 1 open of meteorological autumn 2012 season has posted a deficit and the season as a whole is running 1.3-degrees below normal and 1.8-degrees cooler than at the same time last year.
Thursday marked the 8th day temperatures failed to rise out of the 40s. It's been ten years since a string of 40s of that length has occurred here this early in the season. And, in the years since observations began at O’Hare in 1959, such an early season string of 40s has occurred on only two other occasions
Howling southerly winds, stacked vertically tens of thousands of feet into the atmosphere this weekend, lay the atmospheric groundwork for unseasonable warmth
Southerly ground level winds on the east side of a huge Plains storm system, set the stage for a weekend temperature surge to near 70-degrees Saturday. A max temp just one degree warmer than 70 would tie the 63 year old record for the date set in 1949.
Threat of gusty downpours---some possibly thundery---is to grow Sunday and Sunday night
While a thunderstorm could erupt over parts of the greater metro area as a northbound warm front passes this evening, the coverage of such storms Friday night would be limited.
The optimal set-up for showers and thunderstorms occurs later Sunday and Sunday night. At that time, rainfall could reach 1-2 inches before temperatures dive going into early next week.