Winter Weather in Copper River Basin, Alaska

Alaska DOT reported black ice and icy roads along the Richardson Highway south of Kenny Lake on November 23 and 24. Conditions were classed as Hazardous on November 24. The Gulkana ASOS also reported unknown precipitation at 31 degrees on the morning of November 24, indicating light freezing rain also affected more central portions of the Copper River Basin as well. Temperatures warmed above freezing that evening with the arrival of a southerly Copper River wind.

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.