Up until now it’s been a very mild December in a SSE corridor stretching from Alaska to Arkansas.

The opening 10 days of the month was most unusual with a record breaking snow event from Brownsville, TX all the way along the Gulf Coast and points inland across the South to the Florida Panhandle.

https://twitter.com/weatherchannel/status/943839984762552320

https://twitter.com/AllisonChinchar/status/939491004339671042

Snow along the Mississippi Gulf Coast isn’t unheard of…

https://twitter.com/WTVAJoel/status/938771787629973505

Let’s not forget the devastating month it’s been for fire in California.

https://twitter.com/R5_Fire_News/status/944409301619154944

https://twitter.com/NASA/status/944034008459022336

While it’s been a mild month particularly for the Plains, the final week of December arctic outbreak is sure to significantly dent the positive anomaly over the Plains in particular. The cold holds strong into at least the first 10 days of January in the East.

While one system lifts out of the Ohio/Tennessee Valleys today/tonight, the next coast to coast snow system is beginning to affect the Pacific Northwest and will affect Nebraska and Kansas Christmas Eve and by the end of Christmas Day New England.

Total snow through the end of Christmas day according to the latest GFS run.

The first wave of Arctic air sweeps in on it’s heels.

Check out the GFS snow through 240 hours or January 2! Note along the Gulf Coast!

Cold end to December/beginning of January but what about the rest of the month?

While January opens cold and it’s likely to remain cold in the East through at least the 15th, I expect a flip to colder West, warmer East during the 2nd half of the month. When is the big question.

CFSv2 weeklies show the flip around the 10th.

CFSv2 weekly 500mb height anomaly

2 metre temperature anomaly

The coldest/wildest period of the entire winter is likely between Christmas and January 6, possibly Christmas to New Year.

GFS ensemble temperatures (this is a model blend)

Wed 27th

New Year’s morning

Latest GFS run shows -35 for Grand Forks, ND on Saturday Dec 30.

As the core of cold shifts ESE towards New Years, I expect single digits from DC to New York, possibly 0 for Boston.

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