Cold Then Snow

It's been a dramatic week for weather in central Alaska, with near-record-breaking early cold followed by a new November record for 24-hourly snowfall yesterday in Fairbanks.

The cold snap deepened further after I posted on Monday, and on Wednesday morning the temperature fell to a remarkable -29°F at Fairbanks airport; this level of cold so early in the season was only exceeded in 1975, which reached -30°F on the same date.  The Smith Lake sensor at UAF recorded -35°F, and the North Pole 1N co-op site apparently reached -41°F (although this seems a little low; the other North Pole co-op only reported -32°F).

Here's a 7-day temperature trace from Smith Lake.  With cloud, snow, and a massive influx of warm and moist air aloft, the temperature rose more than 65°F in two and a half days.

 

The mid-atmosphere map from early Friday morning shows a long fetch of strong flow from the west-southwest, which is the classic direction for sustained heavy precipitation in the Fairbanks area.

Up on Munson Ridge, the SNOTEL instrument measured 2.3" of new snow water content over two days, and the liquid equivalent in Fairbanks was a hefty 0.93".  Snow depth at valley level is now up to 19".  Here's some context for the snowfall; this was a big one.

Fairbanks established a Nov 24-hour snowfall record according to @NWSFairbanks. From 8pm Thursday to 8pm Friday, 14.7" (37.4cm) of #snow fell, eclipsing the previous record 14.6" (37.1cm) in 1970. Here are the monthly records through the year. #akwx @Climatologist49 @alasjules pic.twitter.com/Iud3mPR1VA

— Rick Thoman (@AlaskaWx) November 7, 2020

 

I'll add some more on this soon, but heavy snows in Fairbanks are more common during La Niña; the frequency of 8" snow storms is more than twice as high compared to El Niño.