Avalanche Forecast
Regions: Olympics.
Watch for local wind transport and new wind slab formation near ridges and avoid lee slopes receiving wind transported snow. Small loose avalanches on steeper slopes are also possible.
Detailed Forecast
A weather system should lift northward from Oregon Saturday night followed by another system Sunday.  The heaviest precipitation should remain south of the Olympics however if models are incorrect more significant storm snow may be possible by Sunday.  If amounts of new snow are light, only a slight increase in danger is expected.  Watch for more significant storm and/or wind transported snow by Sunday as avalanche danger may increase rapidly if loaded by significant new snow. Â
Light snow showers are expected during the day and temperatures are expected to remain cold but increasing winds are expected.  Small loose avalanches on steeper slopes are also possible.Â
Manage the terrain by avoiding wind loaded lee slopes near and above tree-line. Watch for shooting cracks as a sign of instability. Even a small wind slab in the wrong terrain, i.e. above cliffs or very steep slopes, could have unintended consequences.Â
Snowpack Discussion
A storm arrived at the end of January with rising snow levels and rain above 6000 feet for the Olympics before transitioning to snow and colder temperatures. Wind was less of a factor with this event with a more even distribution of storm snow and a general lack of wind slab during the storm cycle. Only about 1-3 inches of additional snow has accumulated in early February.Â
Very cold temperatures this week have produced strong temperature gradients in the upper portion of the snowpack. The strong temperature gradient has lead to near surface faceting and a breakdown on recently buried crusts and produced weak faceted crystals above the buried melt-freeze crust (see recent images). Â
Surface hoar crystals on N. aspect Klahhane Ridge, Olympics, Friday Feb 7, 2014. Photo, Katy Reid
Faceted crystals above buried crust on N. aspect Klahhane Ridge, Olympics, Friday Feb 7, 2014. Photo, Katy Reid
Moderate east to southeast winds in the Cascades built new wind slab during the week, while winds were much lighter over the Olympics.  Field reports from NWAC pro observers Friday near Hurricane Ridge indicated that new wind slab layers were very isolated to some ridges while most surface snow remained unconsolidated hence lacking the cohesion to produce slab avalanche propagation.
The current weak surface snow structure should rapidly become dangerous when loaded by either additional wind transported snow or warmer more dense storm snow.  see video from Friday Feb 7th: https://www.youtube.com/watch?v=anGcxdg4jfs
Regionally the avalanche danger is lower near Hurricane Ridge than in the Washington Cascades where a more diverse snowpack exists. See the Cascades forecast if traveling there.
The mid and lower snowpack consists mainly of crusts and melt form crystal layers which have generally not been reactive to to snow pit tests. Low snow amounts are continue to limit the avalanche danger on many south slopes and at low elevations due to terrain and vegetation anchors.
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, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
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: Possible
Expected Size: 1 - 1