High Wind — East Turnagain Arm, Alaska

2024-12-09 · East Turnagain Arm, Alaska

Event narrative

An ASOS station in Portage (PATO) reported a maximum wind gust of 85 mph on Monday, Dec 9th at 6:23 AM AKST. Several other stations reported wind gusts in the 50s and 60s including a peak gust of 69 mph in Whittier (WHMA2). Wind gusts remained elevated at around 45 to 55 mph, particularly in Whittier, until around 2:00 PM Dec 9th.

Wider weather episode

A stalled trough over Prince William Sound interacted with a strong occluded front and upper-level shortwave in the Western Gulf. This had the effect of tightening pressure gradients across Southcentral Alaska, which ultimately resulted in widespread gales and localized storm-force gusts over marine areas. Wind gusts in the Anchorage Hillside reached 55 to 60 mph on Sunday Dec 8th in the afternoon. A north-south pressure gradient was expected in the overnight hours of Monday which would reduce the wind speeds in the Anchorage, Portage, and Whittier regions but then realign as the front advanced, raising wind speeds in those areas to even higher heights.

Wind speeds were expected to gust to 55 to 70 mph on the Anchorage Hillside and 45 to 60 mph in Whittier and Portage. However, Portage gusted to 85 mph Monday Dec 9th in the morning hours, exceeding forecasts. On the Anchorage Hillside, winds were light until the front pushed through, which quickly rose and peaked at 81 mph on the upper Hillside and reaching 45 to 55 mph in lower elevations of the city. These strong gusts damaged structures and trees in the Anchorage and Matanuska Valley regions. Power outages were reported due to trees falling on powerlines.

Source: NOAA Storm Events Database, event_id 1227374. Narrative written by the NWS forecast office that issued the report.