Following last night’s rain and wind, another quick shot of cold air is building in for tonight and Thursday before we warm up again. It is the common theme of this winter so far, or lack there of, with prevailing warmth and non-sustainable cold blasts in the eastern U.S. Are things about to change?
There are certainly some fundamental changes in the weather pattern that are taking place and will continue to as we move forward, but does that mean we will start getting sustained cold and snow threats in our area by early January? Not really. With that being said, it is looking like for starters we will see a major arctic outbreak sweep across the eastern part of the country next week, arriving around January 2nd. The cold blast will drop down in response to a very strong ridge of high pressure going up along western North America this weekend, and will provide by far the coldest temperatures of the season all the way down to Florida. This may include readings as low as the teens and single digits in our area. The cold shot will relax within a couple of days, but I think we will have a tendency for ridging to stay in tact for a while longer along the west coast, leading to an additional cold blast or two in the days following a warm up (beyond the day 10 forecast).
We will see a couple of weak disturbances bring the chance of snow/rain showers mainly north of the region through the end of the year (New Years Eve looks dry and not too cold at all by the way). A more widespread snow shower threat may occur around Jan. 2nd with the passage of the arctic cold front. We will then have a strong ridge of high pressure out west and a deep pool of arctic air plunging southward into the eastern U.S. It is plausible that a disturbance diving down this ridge and into the eastern trough could amplify into a storm system beyond January 3rd. Right now there is little-no computer model support forthis to occur anywhere near the eastern seaboard though. It is at least a time period to keep an eye on.
What won’t help those chances is the state of the North Atlantic Oscillation. This will continue to be in a strongly positive phase through the forecast period, and isn’t supportive for snow storms along the east coast particularly in the big cities. The upcoming cold air will be driven by a positive phase of the Pacific North American pattern featuring the ridge out west and trough in the east. We can certainly get a winter storm in this type of Pacific driven cold pattern, however, it could very easily track inland and bring rain to the coastal cities without a cooperating North Atlantic weather pattern.