Monday, January 13, 2025

Major Thaw

December was very warm in Alaska (relative to normal), but January is shaping up to be even warmer; records have been falling in the past week, and the Climate Prediction Center is showing very high probabilities of unusual warmth in the 6-10 and 8-14 day forecasts.  All the cold air has gone south:




Yesterday was extraordinary: widespread temperatures above 40°F in southern Alaska, and as high as 53°F at Nenana; this is only 1°F shy of the January record (54°F in 2009).  The Fairbanks area reached the mid to upper 40s.  Here are 24-hour maximum temperatures ending at midnight last night (note that the plotted 54°F at Nenana is a rounding error - it was 53°F):



For the second time this month, Anchorage saw a daily minimum temperature of 36°F yesterday, tying the January record both times.  But of more immediate concern were the high winds, which caused considerable disruption and damage across south-central Alaska:

https://www.adn.com/nation-world/2025/01/13/anchorage-schools-closed-due-to-weather-related-problems/

Wind speeds exceeding 50mph were widespread not only in the Anchorage bowl but across much of southern Alaska, with much higher gusts in places.  Here are the 24-hour peak gusts (mph) ending at midnight:



The cause of the wild weather is no big surprise: a very large trough over the Bering Sea and a strong low pressure system moving into the Y-K Delta region yesterday.  There was also a strong ridge over British Columbia, enhancing the east-west pressure gradient across southern Alaska.  Here are the surface and 500mb height charts from 3pm AKST yesterday, courtesy of Environment Canada:



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