Blizzard — Northeast Prince William Sound, Alaska

2023-11-20 to 2023-11-21 · Northeast Prince William Sound, Alaska

Event narrative

Alaska Department of Transportation reported very strong winds gusting to 80 mph through Thompson Pass at 8:30 AM AKST 11/20 with blowing snow so severe they could not see the front of their plows. These winds were also verified by a mesonet station in Thompson Pass that recorded a wind gust of 89 mph at 9:10 AM AKST 11/20. Blizzard conditions continued through the evening with winds gusting between 50 and 70 mph through the pass.

Wider weather episode

A strong low pressure system moving up into the Gulf of Alaska was able to interact favorably with Arctic air and strong surface high pressure entrenched over Mainland Alaska to create a very strong northeast to southwest pressure gradient and very strong wind that channeled through gaps in terrain. The strongest winds were focused near and to the southwest of the pass between the Copper River Basin and Matanuska Valley, as well as through Thompson Pass and into Valdez. Recent rounds of snowfall were enough for these winds to resuspend fallen snow and create ground blizzard conditions in both locations. The winds gusting between 60 and 70 mph on 11/20 in the Matanuska Valley were also enough to knock out power to thousands of customers at the height of the wind storm.

Source: NOAA Storm Events Database, event_id 1142433. Narrative written by the NWS forecast office that issued the report.