It’s autumn and the final weekend of September, but it won’t feel that way Saturday. Temperatures are headed for the 80s—the first time Chicago’s official weekend temperatures have reached that level in 3 weeks.
Gusty southerly winds are to accompany the warmth, importing moisture expected to generate a late day overcast. Those clouds assure that the supply of sunshine predicted to grace the area Saturday will fall short of the 100% of possible sun recorded each of the past four days. That four-day run of completely sunny days was this area’s longest in the nearly 2 years since October 2011.
Cold front to bring period of showers Saturday night followed by cooler temps for Sunday
Much needed rain arrives late Saturday and for as many as 4 to 6 hours Saturday night as a cold front sweeps across the area. In its wake, temperatures are to take a hit, returning to the low or mid 70s—levels nearly 10-degrees lower—on Sunday.
While rain is in the forecast, the amounts being predicted will fall far short of what’s needed. The period since July 1has produced just 6.10″ of rain, an amount which is only 53% normal and more than 5″ shy of the historic norm.
History suggests warmth’s NOT over yet; additional 70s and 80s remain a good bet
Sunday’s temperature pullback is temporary. Warmth—including additional 80-degree highs—returns next week.
Chicago’s observational record indicates an average of three additional 80s and 12 additional 70s have occurred from this date forward.
Friday’s 81 was the year’s 80th 80 compared to 101 by this time last year
Friday’s 81-degree high at O’Hare marked the 80th time this year the temperature at the site has reached or exceeded 80.
The impact of this past summer’s wet, cool open is evident from the fact this year’s 80-degree tally to date is 21 days behind the 101 days on which 80-degree readings where recorded a year ago.
Warmth resurges next week in time for October 2013’s Tuesday debut
Southerly winds bring a temperature surge next week to levels more than 10-degrees above normal. October 2013’s open on Tuesday is likely to see peak readings reach the 80s. And 80-degree or higher temperatures are expected Wednesday and Thursday before cooling takes hold later in the week.
Hopeful signs emerging of late week wet spell ahead of a period of pronounced cooling
A pool of warmer than normal air aloft in the arctic regions of northeast Canada and Greenland sets the stage for a blocking pattern beginning late next week which is likely to force cooler air southward into the Midwest. The trend, predicted by more than one medium range global computer forecast model amounts to what forecasters refer to as a “cool signal” for Chicago and the Midwest. Such a blocking pattern is known to lay the foundation for cool weather here.