Winter Weather — Copper River Basin, Alaska

2022-10-14 to 2022-10-16 · Copper River Basin, Alaska

Event narrative

The first confirmation of freezing rain, which was the primary concern across most of the Copper River Basin for the event, came from the Gulkana ASOS reporting freezing rain beginning 8 AM AKST October 15th. A mix of snow, sleet and freezing rain was reported across much of the Copper River Basin all the way through the morning of October 16th, as heavier precipitation finally waned. Numerous webcams across the region revealed accumulating ice occurring during the event as ice began to accrete on camera covers facing into the wind, as well as Alaska 511 (Department of Transportation) road cams recording ice and slush covered roadways. A resident in McCarthy reported a storm total 1.25 inches of rain and 0.25 inches of ice build up. Road conditions were improving at the time of the report on October 16th as warmer temperatures allowed ice to melt.

Wider weather episode

Following quickly on the heels of a heavy snowfall event a few days prior, another low pressure system and front moving into the Gulf of Alaska brought a second round of impactful winter weather that affected a large portion of Southcentral between mainly October 14th and 15th. Once again, cold temperatures in place away from the immediate coast were able to remain stubbornly entrenched over valleys from the surface to around 1000 ft above ground level as warm, moist air advected overtop of the colder air mass in place in association with the low and front approaching the northern Gulf coast.

This system was able to push a much more pronounced warm nose of air above freezing overtop of the colder air in place as precipitation moved across Prince William Sound and into the Copper River Basin on October 14th, then shifting and expanding into the Susitna Valley and Anchorage area on October 15th, with heavier precipitation finally letting up across the entire region by the morning of October 16th. The temperature profile for much of the event was favorable for a mixture of snow, sleet and freezing rain due to the warmer air intruding aloft over a shallow layer that persistently remained below freezing for the duration of the event. The heaviest freezing rain accumulations were reported over the Copper River Basin, where up to 0.25 inches of accumulating ice was observed.

Source: NOAA Storm Events Database, event_id 1061828. Narrative written by the NWS forecast office that issued the report.