Glenn's Blog: Waiting for Winter? Here it Comes | NBC 10 Philadelphia

Glenn's Blog: Waiting for Winter? Here it Comes

...At least for December

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    NEWSLETTERS

    AP

    MILD NOVEMBER: NO RELATION TO DECEMBER

    It’s been yet another amazingly warm month across the country, especially to our west. November in Philadelphia has been about 2 ½ degrees above normal, but parts of the Plains are up to 12 degrees above normal! Here’s the map that shows it:

    It’s also been unseasonably mild in Canada. So how does any really cold air get down into the Lower 48? 

    It has been exceptionally cold in Alaska, with Fairbanks just reaching 30 degrees below zero. That’s a rare feat in recent decades. Now we need to monitor that area to see what happens to that super-cold air. 

    Look at the purple areas at the top left of the current map below. That’s the extreme cold. Most of Canada is in the red or pink colors-WAAAY above normal temperatures.

    Now look what happens over the next week. The map below is valid for next Friday, December 9th.

    The purple and dark blue cold air now covers almost all of the U.S.! And the unseasonably mild air in Canada has disappeared. It just shows how quickly weather patterns can change at this time of year. A mild November has no relation to what December will bring. 

    HOW DOES THAT HUGE CHANGE HAPPEN?

    This is what the upper-air pattern is expected to look like next Friday, according to the European model (the world’s best overall).

    Not only is there an area of very low pressure centered over the Great Lakes, but a big area of high pressure is in Canada. This is part of the blocking patterns we’ve been talking about when predicting a colder winter this year. 

    The December chill won’t necessarily last all month, but the pattern is sure looking more like a much colder and wetter one than November.