Avalanche Forecast

Storm-related avalanche concerns are trending down headed into Christmas Day, but we still don't have a great deal of information about avalanche conditions above 7000 feet where more snow and wind recently impacted avalanche terrain.

As of 12/26, Meadows pro-patrol is still finding weak snow (facets) buried 12/7 in backcountry snowpits between 5500 to 6600 ft on NW through SE aspects, in sheltered terrain roughly 2-3 ft down in the snowpack. The layer is trending toward unreactive. No natural or explosive avalanches have released down to this layer, but we'll continue to track this layer as it evolves over time.

In most parts of the state, a stout melt freeze crust was formed when it rained to high elevations around Thanksgiving. The one exception to this event was in the East North Zone, where the precipitation from the Thanksgiving storm was all snow. A quick storm at the end of November put a small amount of snow above the melt-freeze crust, and preserved the older basal facets in the northeastern areas.

Cold and clear weather dominated the first week in December, with valley fog and very cold temperatures east of the crest. The surface snow sat around and decomposed. Surface hoar grew large on top of this.

A trough centered over the Intermountain West will bring cool N-NW flow to the region as a broad ridge builds offshore on Thursday. The flow will be sufficiently moist to keep low clouds, fog, and a chance of flurries in the forecast. Very weak NW-SE oriented convergence zones will locally enhance snow and cloud in parts of the west slopes Cascades foothills and into the lower passes. Clouds will decrease throughout the day.

Late Thursday night some light snow will arrive in the Olympic mountains from the west as a significant warm front approaches. The Cascades will remain clear and cold.

On Friday, the warm front will be draped parallel to the British Colombia and Washington coastlines. Clouds will lower and thicken with light snow arriving in the Olympics in the morning and in the Cascades by early afternoon. 

Friday night the warm front crosses the region bringing moderate to heavy snow changing to rain at Snoqualmie Pass around midnight as easterly flow in the evening switches to westerly, while Stevens Pass will change to rain after midnight.