It finally got cold in Alaska, well normal for the time of year. On Friday, Fairbanks recorded it’s first sub-0 day which was the third latest in recorded history. Why? Blame or thank the persistent positive which lead to the warm Alaska/cold Lower 48 winter last year and the cold November just gone.

The return of cold up here reminds us that cold is building in the north and when you see modelling suggesting a potential onset of an SSWE, look out down in the Lower 48 because it’s only a matter of time until the arctic, possibly Siberian floodgates open up again. This time ‘January-style’. Alaska has cooled but is already warming again as heights rebuild and the upper pattern reshapes once again.

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Until we get beyond the next few days, it’s downright balmy and rather wet in the run-up to Christmas and Christmas itself for the Eastern Seaboard as a major storm sweeps through the Great Lakes. Expect flooding rain, strong wind and yes severe weather.

QPF rainfall next 3 days

SPC severe weather risk (Christmas Eve)

New York and Boston could both approach 60F on Christmas Day…

Once this system pushes through and heads up into eastern Canada, another system sweeps through. Behind this, we should finally see another arctic high dive south out of western Canada. This is the cold blast I have mentioned frequently for the last 2 weeks between Christmas and New Year. Still on the table despite the current warmth.

Latest GFS by this time next week drops a 1044 high across a broad area of the Western and Central US.

Current snow cover is down to a skimpy 26.3%. Unusually sparse for the days leading up to Christmas.

GFS snow cover at 18z Christmas Day

ECMWF looks a touch more realistic especially with the lack of snow cover in the East.

We continue to monitor the strat warming and while I may have been mistaken about a major cold blast during December in response to new warm burst which occurred towards the end November, I anticipate that an SSWE is looming as the ECMWF and GFS show an overwhelming warmth of the stratosphere which may finally split the vortex. The AO/NAO has been negative and thus supporting a Pacific-zonal pattern across the continent with any arctic air held way up in arctic Canada.

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