Will the roller coaster of early winter temperatures continue?

The past month was very clearly split into two nearly equal but opposite halves temperature-wise.

The first 15 days of November were routinely, though not exclusively, below normal with 10 days falling into that category. In fact, the eight days from Nov. 6 to Nov. 13 were consecutively below normal, with the morning low of 9 degrees on Nov. 10 setting a daily record.

The early cold left us averaging 5.1 degrees colder than normal through November 15. Only three additional below-normal days occurred after the halfway point. Remarkably, beginning on Nov. 23, the month ended with eight consecutive days of above-normal temperatures, including the record high of 64 degrees on Nov. 24.

The warm second half of the month averaged 3.9 degrees above normal so, overall, November was just 0.6 degrees colder than usual even after its brutally cold start.

This latest extended period of unusual warmth will be over after today, however. Forced by the influence of successive strong cyclones in the Gulf of Alaska at the end of November, the mid-tropospheric flow over North America has transformed quickly. We are now poised to intercept a cold northwesterly flow originating in far northwestern Canada.

Overnight into Tuesday, temperatures will plummet as we head into an extended and exceptional cold snap to start December. The lack of snow cover will mitigate this upcoming chill to a great extent, but it is likely we will not enjoy another warm day like today for some time. Enjoy it while you can.

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month.
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