Avalanche Forecast
Regions: Olympics.
Shallow wind slabs may linger in wind exposed terrain above treeline while small loose wet avalanches are possible on steep solar slopes. In some areas, firm surface crusts will make for difficult travel conditions so be prepared to self-arrest and think about the sliding hazard before crossing steeper slopes.
Detailed Forecast
After a cloudy start, partly to mostly sunny skies are expected Wednesday afternoon with continued mild temperatures.Â
Lingering wind slabs should be far less sensitive to triggering on Wednesday and confined to higher terrain. Continue to watch for areas of recently wind transported snow such as fresh cornices, snow drifts, and uneven snow surfaces. Identify and avoid locations where recent wind loading occurred.
Wind slabs can be deceptively difficult to manage in the terrain. Take a moment and read our recent blog post by NWAC Pro Observer Jeremy Allyn on wind slabs.
Small loose wet avalanches are possible on steep solar slopes in areas that experience warm temperatures and afternoon sunshine on Wednesday. Be aware of the consequence of even a small loose wet avalanche around terrain traps. Â
In some areas, firm surface crusts will make for difficult travel conditions so be prepared to self-arrest and think about the sliding hazard before crossing steep slopes. Â
Despite all this new snow, early season hazards still exist. Many creek beds have still not filled in for the winter.
Snowpack Discussion
Mild weather seen Sunday through Tuesday has allowed lingering wind slabs to gain strength.
SW winds Friday night redistributed new snow forming shallow wind slabs on lee slopes at higher elevations. This resulted in a variety of snow surfaces including soft unconsolidated snow, wind scoured slopes, rain crust, and firm wind slabs.
The 12/16 mid-December crust can still be found 2-3 feet down within the snowpack.
Observations
NWAC pro observer, Matt Schonwald visited Hurricane Ridge on Friday, 12/29 and stressed that this is a different snowpack than the Cascades! He visited W-NW-N-NE aspects and found the 12/16 crust and 1-2 mm facets down 2.5 feet. Several PST tests failures, self-arrested, but propagated through most of the column along the 12/16 layer. This PWL will mostly likely be found below ridgelines and will have to be watched moving forward.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, West, North West.
Elevations: Alpine.
Likelihood: Unlikely
Expected Size: 1 - 1
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1