Blizzard — Copper River Basin, Alaska

2022-01-01 to 2022-01-03 · Copper River Basin, Alaska

Event narrative

Extreme whiteout conditions were reported by DOT on the Richardson Hwy from MP 180 to MP 210, especially near Summit Lake. This was due to the strong winds lifting snow off the ground and creating ground blizzard conditions.

Wider weather episode

A ridge of high pressure aloft shifted northeast out of the western Bering Sea on December 31, 2021, strengthening over northern Alaska January 1-3, 2022. The development of this ridge, caused an extremely cold air mass over northern Alaska to dive southward across southern Alaska and into the Gulf of Alaska. This is an ideal setup for a Bora wind event over Southcentral Alaska, whereby very cold air is forced over the Alaska Range and southward across Southcentral Alaska, leading to widespread strong and gusty winds and cold temperatures. This set-up allowed several noteworthy details to occur:

1. Very cold air, bottoming out at about -31F to -40F, moved over the Alaska Range and into the Copper River Basin at about 3kft above ground, on January 2nd. Surface temperatures dropped to single digits on the 2nd, and below zero on January 4th.

2. Amplified pressure differentiations developed between the northeast Gulf and northern Alaska. The strengthening surface low over the Gulf dropped to about 972 mb, while an extremely strong surface high topped out around 1052 mb on January 2nd. This created extremely tight pressure gradients between the northern Alaska high and the Gulf low, especially over Southcentral Alaska. This led to the development of strong winds from the northeast over the period, accelerating through the Matanuska Valley.

3. The presence of both thermal and pressure gradients combined to create much stronger winds than would otherwise be observed if standing alone.

While the region hardest hit by this high wind and cold weather event was along the Matanuska-Susitna Valley, many other locations across southcentral were also impacted by frigid temperatures and windy conditions.

Source: NOAA Storm Events Database, event_id 1018096. Narrative written by the NWS forecast office that issued the report.