Avalanche Forecast
Regions: Olympics.
Strong winds Friday and Friday night will have built fresh wind slab on lee aspects mainly near and above treeline. Watch for new wind slab in the upper portion of the below treeline band. Easterly aspects will be highlighted in the elevation/aspect diagram but watch for firmer wind transported snow on a variety of aspects.
Detailed Forecast
Light to moderate showers Friday night should taper off after midnight with only isolated light snow showers expected on Saturday. The same trend is expected for the moderate to occasionally strong W-SW winds forecast for Friday evening with winds easing considerably heading into Saturday.
Strong winds Friday and Friday night will have built fresh wind slab on lee aspects mainly near and above treeline. Watch for new wind slab in the upper portion of the below treeline band. Easterly aspects will be highlighted in the elevation/aspect diagram but watch for firmer wind transported snow on a variety of aspects.  Â
Despite the cooling trend, new and shallow storm slab instabilities may be locally sensitive.Â
Wet slabs will not be listed as they are very unlikely due to the cooling trend. However, for one more day avoid travel below unsupported slopes, especially below treeline, with the low likelihood/high consequence of large wet slab avalanches in mind. Wet slab releases are hard to predict and can happen a day or two after peak warming and rainfall. Â Â
Snowpack Discussion
Weather and Snowpack
A strong storm cycle was seen Friday through Monday with about 3 feet of snow accumulating at Hurricane Ridge.Â
A strong plume of moisture brought heavy rain to the west slopes of the Cascades and Olympics. About 2 inches of water fell mainly as rain at Hurricane Ridge from Wednesday afternoon through Thursday afternoon with significant snowpack settlement. A strong cold front swept through mid-day. Bands of light to moderate showers in SW flow followed the front with a slow cooling trend beginning Thursday afternoon. Â
Moderate showers and strong W-SW winds along with a cooling trend was seen on Friday. About 10 inches of snow accumulated at Hurricane Ridge through 6 pm Friday.Â
Recent Observations
NWAC observer Matt Schonwald was at Hurricane Ridge on Friday and found good skiing in non-wind affected areas well below ridges. Closer to ridgeline, new wind slab was quickly building on lee easterly slopes up to 1 ft deep and very sensitive to ski triggering with cracking readily observed on test slopes. One large loose wet avalanche was observed by the road crew Friday morning, with a few small trees in the 6-8 ft debris pile. Large cornices that had built on W-NW aspects earlier in the week were quickly being eroded by the strong W-SW winds. 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, South.
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: Possible
Expected Size: 1 - 1