UPDATED: Wednesday, December 8th, 2021
After the 4th Warmest Autumn on record, December shows no signs of flipping the pattern. At least, yet. The only subtle change is that November wasn't as crazy above normal as more recent months, though. Still, the month averaged 2.2° above normal, a significant amount (October for reference which was the 10th warmest October on record was 6.1° above normal).
(If you wanna just cut to the chase: scroll to the end for some numbers/summary)
Below: November 2021 temperature anomalies (difference from normal).
Arctic portions of northern Canada & Hudson Bay really stand out as very warm the past month which has had severe consequences on delaying the normal freeze up of Hudson Bay. Sea ice on Hudson Bay is critical for the world's farthest south dwelling polar bear population. (Polar bears need sea ice to hunt seals on- they rarely can catch one in water).
Yet again, the European model seemed to nail the pattern. BELOW is a comparison of the actual November temperature patterns & the European model forecast.
Big shocker. I'm all but certain December 2021 will be yet another warmer than normal month. It will be our 10th consecutive. The only month in 2021 that will go down as cooler than normal will be February. All because of those 2 cold weeks (Feb. 5th-20th).
Crunching the numbers through the first half this month which we have a pretty decent confidence in, shows that unless it's SUPER cold around Christmas/New Year's, the month will end up similar to November, on models levels of 2° to 3° above normal.
The first half this month will be the warmest (relative to normal: obviously the early December is almost always warmer than the end in actual temperature terms). The first half of the month looks to average near 5° above normal but all the models indicate some cold the last week or 10 days of the month- but unlikely to be cold enough to erase the surplus we're already developing.
The most concerting bit of warmth is what the models are forecasting for mid month (week of Dec. 12-19) with high temperatures up to 25° above normal potentially!
Below: Forecast temperature anomalies for Dec. 15 (European model in deg °F)
The other critical thing is snowfall. While a week ago I might have given us slightly better odds of a White Christmas than not, now, I think that figure is decreasing. Temperatures mid-month, just before the holiday are warm enough to melt almost any snow storm that's less than a half foot away. In other words, snow depth & snow totals for a month can be two different things in a month of wild temperature swings.
Below: Snowfall (running total for the month by date) for December 2021:
Even so, I anticipate the lingering drought conditions of summer & fall to continue into at least he first half of our winter. Normal December snowfall is 11.8", I anticipate that figure being more like 7-8" this December. That would be optimistic even, given our Autumn precip trends. November for example saw just 52% of our normal precipitation. Autumn overall was at 58%. Applying that figure to December would yield only 6.8" of snow. Let's hope we do better.
Below: SNOW DEPTH forecast for December 2021.
So, here, in summary is my December Outlook by the numbers:
In case you're curious what the NOAA (/CPC: Climate Prediction Center) forecast for December is, for what that's worth.
I think they're under-doing the warmth chances & too optimistic on precipitation. The drought continues to affect our weather patterns as does the warm pattern in the background of a warmer globe.
-Meteorologist, Sven Sundgaard
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