Following the mildest November of record, December brought more record temperatures to Utqiaġvik (Barrow). The average temperature for the month of +5.7°F (-14.6°C) was by far the highest December average in 98 years of record. The previous warmest December was in 1983, when the average temperature was +0.6°F (-17.4°C).
Bettles was very snowy the first three weeks of December. Measurable snow fell on 20 of the first 21 days of the month. The total snowfall for the month was 32.4", more than twice normal and enough to make 2017 the sixth snowiest December in the past 73 years.
Thompson Pass, at 2600' elevation on the Richardson Highway, is one of the snowiest places in Alaska that people regularly access, and is no stranger to big snowfalls. On December 6 the Alaska Department of Transportation (DOT) reported that 40" (101cm) of snow fell in 12 hours and a whopping 15" (38cm) of snow in 90 minutes. The heavy snow triggered an avalanche more than 20 feet (6m) deep over the Richardson Highway, which was closed for more than a day until DOT could clear the road.
In this issue: Experimental Arctic Prediction, Sea Ice: Summer & Autumn 2017 Climate Review May–Oct '17, News & Events
Sea ice was extraordinarily slow to grow during November in the Chukchi and Bering Seas near Alaska. Ice started to grow out from the coast during the last ten days of the month, but a huge area of the offshore Chukchi Sea and nearly all of the northern Bering Sea remained ice-free. The combined Chukchi and Bering Sea ice extent was less than half of 1981-2010 average and 20% lower than the previous lowest (2014) in the satellite era (since 1978).
With open water in the Chukchi Sea to the west of Utqiaġvik (Barrow) virtually the entire autumn, it's not surprising that 2017 ended up as the third warmest September through November autumn season in the past 98 years. The average temperature of 25.4°F (-3.7°C) was 8.7°F (4.8°C) above normal. The only milder autumns were in 1998 at 25.8°F (-3.4°C) and 2016 at 26.0°F (-3.3°C). Climate observations have been made at Utqiaġvik since autumn 1920.
This was the fourth warmest autumn of record at Bethel, and the second warmest since 1926. The average temperature for the three months, September through November, was 36.0°F (2.2°C). The is almost five degrees above the 1981-2010 normal. The only autumn in recent decades that was milder was in 2002, when the average temperature was 36.4°F (2.4°C).
November was unusually dry in Sitka, with only 3.11" (79.0mm) of precipitation. This is less than one-third of normal and ranks as the fifth driest November of record at the Sitka Airport. Climate observations have been made at the Sitka airport since the mid-1940s.
Yakutat is typically a very wet community, averaging more than 14 inches of precipitation in November alone. However, this November was exceptionally dry. Only 2.14" (54.4mm) of rain and melted snow fell, making this the second driest November of record. The only drier November was in 2006, when there was just 1.82" (46.2mm) of precipitation.