Avalanche Forecast
Regions: Olympics.
Recent deep storm and wind slab deposits should be given ample time to settle and stabilize, especially due to the slow stabilization rates given the expected cold temperatures. Human triggered avalanches should remain likely on Monday. Choose low angled terrain and avoid slopes connected to avalanche paths with wind loaded start zones.
Detailed Forecast
Continued storm snow deposits overnight Sunday should give way to partial clearing Monday as high pressure affects the area. Winds should be light Sunday night and Monday with further cooling.  Â
While the ending showers with light winds and cold temperatures should lead to an overall improving avalanche danger Monday, there has been such significant storm snow, along with periods of moderate winds over the past three days, that another day or more of very cautious travel in backcountry terrain is urged.
Storm and wind slabs should begin to slowly settle and stabilize beginning Monday. However, careful snowpack evaluations, cautious routefinding and conservative decision-making will remain essential, as these dangerous avalanche conditions slowly improve.
Choose low angled terrain and avoid slopes connected to avalanche paths with wind loaded start zones.Â
Loose dry will not be listed as an avalanche problem, but in steep terrain lacking a slab structure, continue to watch for small loose dry avalanches near terrain traps like cliff bands where even small avalanches can have big consequences.Â
With deep unconsolidated snow in many wind protected areas, there remains an increased risk for tree well and snow immersion suffocation at this time. Ride or ski with a partner and keep them in sight at all times!
Even though the lower part of the below treeline band is filling in, watch for early season travel hazards such as barely covered rocks and open creeks.
Snowpack Discussion
Weather and Snowpack
An active and cool weather pattern has resulted in a snowy December thus far with the Hurricane Ridge NWAC station recording about 6 feet of snow, with over 3 feet in the past three days through Sunday afternoon!Â
Cold and fair weather early last week likely allowed near surface faceting and/or surface hoar to become widespread. Beginning Wednesday night and through Thursday, considerable wind transport from easterly winds occurred near and above treeline.Â
Beginning Thursday night and continuing on Friday, a switch to south-southwesterly winds occurred along with a moderate warming trend and light snowfall.Â
Prior to this new snow, the snowpack in non-wind affected terrain was generally right side up with low density snow at the surface and no problematic layers in the lower snowpack.
Deep storm snow deposited over the past three days now overlies the old snow layers with storm snow of 2-3 feet or more common.  Â
Recent Observations
Moderate easterly winds midweek likely built new wind slabs on lee aspects near and below treeline in the Hurricane Ridge area with plenty of low density of snow available for transport. A switch to light S-SW winds late this week may have redistributed snow to more traditional NW-NE aspects Friday.Â
This redistribution of recent and new snow continued on Saturday with additional new storm snow and moderate SSW winds.Â
The Ranger at Hurricane Ridge indicated widespread natural slides had reached the road in many places by Sunday morning, likely releasing overnight during moderate to heavy snowfall and moderate winds.
We don't have any snowpack observations identifying persistent weak layers in the Hurricane Ridge area so we have a large amount of uncertainty whether new wind and storm slab avalanches will step down to deeper layers.Â
Avalanche Problems
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1