High Wind — Pribilof Islands, Alaska

2022-09-15 to 2022-09-17 · Pribilof Islands, Alaska

Event narrative

Buoy 46035 (250 nm West of Saint Paul Island) reported a pressure of 28.08 inches (950mb) Sept 16/1650UTC (850 AM) as the center of Merbok reached it's closest proximity to the Pribilof Islands before continuing northeast. Wind gusts peaked at around 74 mph at the PASN ASOS, while waves observed to 46 feet by about 7 AM Sept 16th. At 950 AM seas up to 52 feet were observed by the closest buoy.

Wider weather episode

The remnants of Typhoon Merbok in the northern Pacific Ocean began approaching the Bering Sea on Thursday, September 15, 2022. This storm transitioned into an extra-tropical area of low pressure and strengthened as it traversed the Bering Sea from southwest to northeast. Impacts were first observed with high winds in the Central and Western Aleutians early on Friday, September 16. The storm continued to move northeast and peaked in intensity on Friday with a minimum central pressure of 937 mb at 4:00 AM, which is the lowest pressure ever recorded in the Bering Sea for the month of September (data since 1950). More remarkably, it appears to have been the lowest pressure recorded for any time of year along portions of its track. The storm slowly weakened but remained very powerful as it moved through the Bering Strait on Saturday morning September 17, taking a perfect track to bring significant coastal flooding to the northern Bering Sea coast. The storm continued to move northeast into the Chukchi Sea Saturday afternoon, September 17 and stalled out, gradually dissipating through Tuesday, September 20 over the Chukchi Sea.

The impacts on Friday were mainly over the Bering Sea and the Pribilof Islands in the form of high winds and seas. Buoy 46035, located at 57.016N, 177.703W in the Bering Sea recorded wind gusts to 76 mph and seas of 52 feet Friday morning. By Friday evening, and into the weekend, the low moved towards the western Alaskan coastline, bringing high winds and near record storm surge.

What made this storm unusual was threefold: Storm strength, storm track, and the speed of its movement. As Merbok's remnants approached the Bering Sea, an eastward transitioning disturbance reinforced the storm's strength by infusing its energy into Merbok's remnants, while merging cold, dry air aloft (pulled from continental east Asia), with the tropical surface air below. This interaction increased the storm's strength exponentially, while facilitating the storm's extra-tropical transition. While it is common to get Hurricane-Force winds during the Fall and Winter in these extra-tropical systems, the strength of the storm was historic for the month of September. Additionally, the Bering Sea's strongest storms typically occur when there is some sea ice present to buffer and protect the coastline from wave action. In September, there is no sea ice in the Bering or Chukchi Seas, leaving the coastline vulnerable to wind driven waves, along with the storm surge.

Also of note were the storm's track and speed of movement. Merbok tracked from the Southwest Bering Sea in a nearly straight line into the Bering Strait at a speed that induced a 'dynamic fetch.' This means that the storm moved at the same speed as the waves it was generating, causing winds to continue to build the same areas of high seas, thus resulting in sea heights over 50 feet. The straight line of the track to the Bering Strait meant that these huge seas, once generated, were sustained by the storm until it deposited these seas into the Western Alaska Coastline. This is what caused the record breaking storm surge at some locations.

A myriad of impacts were noted across the West Alaska Coastline. While waters rose in many villages, homes became uninhabitable or lifted off their foundations, and roads were washed out, local community leaders have stressed that many of their villages have sustained a serious loss in their way of life. Of note is the fishing fleet loss, and the many fish camps and smoke houses damaged or lost across many villages. This is more than just a physical loss of possessions and property. These camps have been in families for generations. This is a loss of food security and a place to teach traditional practices and values to the kids.

Flood specific:

High winds and heavy rain from the remnants of Typhoon Merbok caused flooding from heavy rain and wind driven backwater along the Kuskokwim River from Bethel to the Kuskokwim Delta. Heavily impacted were the towns of Napakiak and Oscarville which are located below Bethel, the nearest river gage location. Minor flooding was also likely around the Brown Slough in Bethel. Many small villages in ungaged locations were impacted from this event.

Source: NOAA Storm Events Database, event_id 1059046. Narrative written by the NWS forecast office that issued the report.