Cold/Wind Chill — Nern P.w. Snd, Alaska

2022-12-23 to 2022-12-24 · Nern P.w. Snd, Alaska

Event narrative

Temperatures initially rose with the arrival of a cold, dense airmass during the early morning hours of December 23 as northeasterly winds vertically mixed warmer air aloft down to the surface across Northeastern Prince William Sound. However, colder air gradually worked in throughout the day, allowing temperatures to fall. The Alaska Department of Transportation reported 25 to 45 mph winds through Thompson Pass, causing wind chills below -40F by December 24. Winds diminished late on December 24, ending the cold wind chills.

Wider weather episode

A strong upper-level trough originating in the Arctic dove southwestward across Southcentral Alaska on the evening of December 22 through December 23, bringing a reinforcing shot of cold, dense Arctic air into an already cold environment. This combined with a pre-existing strong pressure gradient between strong surface high pressure in Interior Alaska and low pressure over the Gulf of Alaska to produce strong winds through gaps and passes across southern mainland Alaska. Blizzard conditions were seen in the Matanuska Valley, where 65 to 83 mph winds lofted snow and reduced visibility. Winds knocked out power to 7000 residents in the Matanuska Valley and the Anchorage Bowl. Blowing and drifting snow, as well as wind chills as low as 55 degrees below zero were also observed in other portions of Southcentral Alaska.

The trough closed off into a low pressure system aloft late on December 23 as it began to track westward across Southwest Alaska and into the Eastern Bering Sea, allowing conditions to gradually improve over Southcentral Alaska. The upper level low began to interact with a weak surface low crossing the Alaska Peninsula into Bristol Bay on December 24, dropping snow in both regions. Combined with gusty winds, blowing snow affected portions of Bristol Bay and the Pribilof Islands on the evening of December 24 into the morning of December 25 as the system continued into the eastern Bering Sea. Active weather diminished as the low tracked further west into the Bering Sea over the following days.

Source: NOAA Storm Events Database, event_id 1096992. Narrative written by the NWS forecast office that issued the report.