Chicago Enjoys It’s Mildest Mid-December Since 1939

Tom Skilling writes:

The temperature turnaround since December’s opening week has been remarkable.  The metro area is in the midst of its mildest mid-December period in the 67 years since 1939 - a major change from the chill which gripped the area in this month’s opening 8 days.  That opening was the 6th coldest December here since 1870.  The 40° average temperature over the past week and a half is running 11.8° above the 136 year average.  Only five December 10th-20th periods have been milder.  The period is running more than 20° warmer than the same period a year ago.

This fact worries me.  An analogy that a lot of meteorologists like to use is that weather patterns are like a rubber band.  The farther you pull it in one direction, the harder it snaps back the other way.  One could also liken this to a pendulum.  This long period of warmer than normal weather is lending credence to the idea that we will see a major pattern change early in the new year, leading to periods of extreme cold.  Of course there are other factors, but this is usually a good rule to get a gut feeling about things.