Winter Storm — Bristol Bay, Alaska

2023-01-27 to 2023-01-28 · Bristol Bay, Alaska

Event narrative

The first report of significant ice accretion came in from a meteorological technician at the King Salmon Weather Service Office at 3 PM 1/27. The technician reported it was like a skating rink, with 1/4 inch layered crust built up on the snow pack before temperatures warmed above freezing during the afternoon hours. Meanwhile, the Dillingham AWOS reported continuous freezing rain beginning 11 AM 1/27 and lasting through about 10 PM. By around this time, much of the area surrounding Dillingham began to see southeast winds warm temps above freezing and change remaining precip to rain, while Togiak also changed over to rain and hovered just above freezing starting earlier in the afternoon.

Numerous webcams around Dillingham also showed appreciable ice accretion on top of camera covers facing into the prevailing wind, resulting in distorted and blurry imagery from webcams that worsened as more ice continued to build up.

NWS Anchorage called the Lake and Peninsula Bourough Emergency Manager who reported there were some cars off the road in Naknek on 1/27 but no ice/freezing rain totals were reported. In a follow-up conversation with the Dillingham fire chief, the worst impacts were reported, with just less than 1/2 inch of icing and most severe conditions on 1/27 reported. Precipitation changed to rain sometime late in the evening of 1/27 to early morning of 1/28. Road crews sanded in advance on 1/27, but roads got messy by the evening hours. Not a lot of people were traveling before 9AM on 1/28, with pretty bad conditions and some cars sliding off roads.

Wider weather episode

A classic setup for freezing rain across portion of Southwest Alaska took shape beginning on the afternoon of 1/27 as a warm front working north over the eastern Bering Sea and up the Alaska Peninsula slowly progressed north into a retreating Arctic air mass initially in place across most land areas of Southwest. Temperatures at the surface were mainly at or below 15 Fahrenheit to start off the early morning across much of Bristol Bay and interior parts of the Kuskokwim River Valley. Farther south, the warm front began to work north up along the Alaska Peninsula, pushing in southeast winds and temperatures in the mid 30s to low 40s in its wake.

The shallow cold air mass in place farther north with north to northeast winds holding on for most of the day at the surface allowed for a significant frontal overrunning event to occur, with a warm nose of air above freezing streaming out ahead of the surface warm front. An inversion only a few 100 to few 1000 feet thick below the warm layer allowed for several hours of melting snow to fall as freezing rain at ground level in a number of favored locations across Bristol Bay. About 0.25 inches of ice accretion was recorded at King Salmon during the morning hours of 1/27 before the front pushed through in the early afternoon and allowed temperatures at ground level to warm above freezing.

Farther north, northerly winds continued to dam cold air into the Kuskokwim Mountains for much longer, leading to many hours of accumulating freezing rain for Dillingham and Clark's Point, where nearly 0.5 inches of icing was recorded before the front finally pushed through and warmed surface temperatures above freezing during the evening hours of 1/27.

As the front continued to progress north into the Kuskokwim Delta, it began to accelerate, resulting in a faster transition from snow, to freezing rain, then to rain for areas between Quinhagak and Bethel as winds turned from northeast to southerly and as warm air began to flood in at the surface. This resulted in much lighter ice accretion less than 0.1 inches and lower impacts for areas in and around Bethel.

Source: NOAA Storm Events Database, event_id 1099935. Narrative written by the NWS forecast office that issued the report.