A rare late-season string of 60-degree temps appears possible as December and meteorological winter arrives this weekend; it’s been 30 years since that last happened

 

Only twice over Chicago’s 142 year observational record dating back to 1871, has a December opened with three consecutive 60s. It last happened in 1982 as a strong El Nino took shape over the equatorial Pacific—and, from all appearances, 2012 may become the third! There’s no El Nino involved this time. But, arctic air is in full retreat back to Canada, a product of shifting upper steering winds which are cutting off the supply of frigid air while promoting a flood of mild Pacific air across the country.  This sets the stage for the  unseasonable warmth which we are predicting.

 

Wednesday’s 44-degrees high at O’Hare was an 11-degree increase over Tuesday’s chilly 33

 

Warming proceeded into a second day Wednesday with temperatures surging to 44-degrees at O’Hare—an 11-degree increase over Tuesday’s 33-degree high. But even warmer days lie ahead.

 

Mammoth Pacific storm, with a circulation 4,000 miles across, lambasting the West and setting the stage for coast-to-coast “warming”

 

A mammoth winter-type storm has assembled over the Gulf of Alaska and spans an area covering virtually the entire eastern Pacific. The moisture this storm is hurling onto the West Coast—as well as a barrage of huge three-story waves—are being driven by the system’s expansive wind field, one which spans an area nearly 4,000 miles across.

 

The onshore flow is to translate into the mild air expected to surge into the Midwest and across most of the country once these Pacific winds descend out of the mountains and into the Plains in coming days where they’ll produce compressional warming.

 

Meteorological winter and December to open with October-level warmth

 

The highs of 60, 64 and 66-degrees predicted Saturday, Sunday and Monday are the equivalent of October-level temperatures. They represent readings which are more than 20 degrees above early December norms.