Thursday, November 29, 2012

A Cold November does not Portend a Cold Winter

To state the conclusion up front: the average November temperature in Fairbanks is of NO predictive value for the mean temperature of the upcoming winter.

November 2012 is going to be one of the coldest November of record (though not in the coldest three). What does this mean for the upcoming winter? Nothing at all.

Overall, the linear correlation between November mean temperature and the subsequent winter (December through February) mean temperature is only 0.12 (1919-2011). Looking just at the coldest Novembers, it is not any better.

Above is a scatter plot of the 20 coldest Novembers (1919-2011) and the mean temperature during the subsequent winter. Ten of those winters had mean temperatures above the 1919-2011 mean and ten were below the long term mean. Eight of the 20 Novembers wound up being colder than the following the winter. The coldest November (1926, with a mean of -11.2F) was followed by an exceptionally warm winter (mean temperature of +3.2).  

So feel free to forecast colder than normal for the upcoming winter. Looks like you have a 50-50 chance of being right. 

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