Winter Weather in Kuskokwim Delta, Alaska

A weak front off a deep, occluded low centered near the eastern Aleutians tracked northward across Southwest Alaska on Nov 22. A band of light precipitation led to a mix of precipitation types across the Kuskokwim Delta that evening, with light rain reported by the Bethel ASOS at below freezing temperatures for several hours, before warming up above freezing. To the northeast in Kalskag, precipitation fell as snow. Temperatures were above freezing in Chefornak, indicating that rain fell along the coast. Atmospheric conditions were ripe for freezing rain near Bethel with east to northeasterly wind keeping cooler temperatures near the surface as southerly flow caused warm air to ride over top of it with the arrival of the front.

After a stretch of very cold temperatures associated with Arctic high pressure, a much warmer and more active pattern took shape across Southcentral and Southwest Alaska as multiple low pressure and frontal systems rotated north around a broad, deep low centered over the Aleutian Islands. The deep southerly flow aloft transported much warmer air north with each system. Colder air was able to hold on at the surface over interior valleys and lower elevations even as warmer air above freezing streamed north and west a few thousand feet above sea level. This resulted in favorable conditions for freezing rain and drizzle, with multiple rounds of freezing rain causing difficult travel conditions between 11/21 and 11/24 before temperatures at ground level finally warmed above freezing for most of the southern Mainland.