Blizzard — Matanuska Valley, Alaska

2022-12-23 · Matanuska Valley, Alaska

Event narrative

Surface observations indicated blowing snow began around midnight on December 23 as northeasterly gap winds rapidly developed and conditions worsened through the day. Winds were sustained at around 40 knots (46 mph) at both the Palmer and Wasilla surface observing sites for nearly 21 hours from the early morning through nearly midnight. Wind gusts reached 71 knots (82 mph) at the peak of the event (405 PM December 23) as observed by the Palmer ASOS. Blizzard conditions were most widespread and were recorded at both the ASOS in Palmer and the AWOS in Wasilla around midday December 23. The Wasilla AWOS stopped reporting any data during the peak of the event.

This wind event was exacerbated by the amount of snow on the ground; snow that had fallen earlier in the month. Ground blizzard conditions were noted at several area weather stations as snow and blowing snow, as well as visibilities reduced

to a quarter mile at times over the period. At least 2000 residents lost power in the Matanuska Valley as a result of the winds.

While winds were less notable across the Anchorage Bowl during this event (with gusts reaching into the 60 mph range), these gusts did cause blowing and drifting snow impacts along the Knik Arm, affecting the northern portion of town and leading to power loss across portions of Anchorage as well.

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 1095756. Narrative written by the NWS forecast office that issued the report.