December Warmth Isn't Going Anywhere | NBC 10 Philadelphia

December Warmth Isn't Going Anywhere

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    NEWSLETTERS

    NBC10 Meteorologist Brittney Shipp is in Conshohocken for a holiday parade during a warm December. (Published Thursday, Dec. 10, 2015)

    If You Think November Was Unseasonably Mild
    It was the 2nd warmest November in Philadelphia’s recorded history. Temperatures averaged 5.6 degrees above “normal.” (I had predicted November to be 4 to 6 degrees above normal.) Well, the first week of December has been even more extreme, averaging 6.2 degrees above normal. And with the way the pattern is setting up, that number is likely to be higher a week from now, after some near-record warmth hits the area.

    It’s Not Just Here
    Below is a map of temperatures compared to normal (or “anomalies”) over the entire country Tuesday. EVERY part of the country is warmer than normal (except for extra-cold Alaska, which is off the map):

    And, yes, all of southern Canada is relatively warm, too. So how could we get anything but unseasonably mild air moving in here? We can’t. Even a Northwest wind coming from Canada would bring in mild air. It’s an awfully frustrating pattern for cold and snow lovers. But, if it makes them feel any better, they’re saving a lot on heating bills.

    Then It Gets Even Warmer
    After a couple of relatively cool days (still above normal), the big blob of warm air will start moving in. And what a blob it is! Here’s a map of temperature anomalies for Sunday, at the time the Eagles will be playing the Buffalo Bills at The Link:

    That should be the peak of the warm spell, with temperatures at least into the mid-60s. The record high in Philadelphia Sunday is 65 degrees, set in 1931. That’s why we are predicting “near record warmth” for Sunday.

    And What About The Rest Of December?
    We’re still looking for any changes in the overall weather pattern, whether it’s in the U.S. or elsewhere around the globe. There are no borders in the atmosphere, so what happens in China-or the North Pole-or Russia could have an impact on our weather sometime in the future. As mentioned in previous blogs, we especially look for “blocking patterns” that can influence weather thousands of miles from where they form. But a global view shows something else unusual-there are NO significant blocks anywhere in the Northern Hemisphere by the middle of December (specifically on the 17th in this map from the world-best European Model).

    This means it’s going to be hard for a major pattern shift before Christmas. Temperatures could be closer to normal by then, but as for the chances of a reversal of the mild pattern? I’d have to say there’s no evidence of that at this point.

    My Predictions
    In my winter forecast issued Nov. 13, I predicted December would be about 4 degrees above normal. If anything, that number looks too low. And I predicted January would be about 6 degrees above normal, with only 7 total inches of winter snow by January 31st. There’s no reason to change those forecasts at this time. But that doesn’t mean the whole winter will be like that. There is still a good chance of a big reversal for the second half of the winter season.