Avalanche Forecast
Regions: Olympics.
Loose wet avalanches are unlikely but still possible, especially above treeline on slopes that have not already released. Also watch for isolated pockets of shallow wind slab on lee slopes above treeline.
Detailed Forecast
An approaching frontal system should cause cloudy skies, moderate S-SW winds and periodic light rain and snow Friday in the Olympics. Â
Loose wet avalanches are unlikely but still possible, especially above treeline on slopes that have not already released. Also watch for isolated pockets of shallow wind slab on lee slopes above treeline.Â
Less recent snow and ample terrain anchors should greatly limit the avalanche danger below treeline.Â
Due to the low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation. Many areas below treeline do not have enough snow to cause an avalanche danger.
Snowpack Discussion
Last weekend another warm and wet system brought a one-two punch to the Pacific Northwest. The initial system Saturday brought mostly rain with a few inches of snow at Hurricane. This was followed by a welcome 16-18 inches of new snow Sunday at the NWAC Hurricane Ridge station. A frontal boundary stalled over southern British Columbia brought persistent light rainfall to Hurricane Ridge on Thursday, with the snowline likely extending to 6500 feet or higher.Â
NWAC observer Tyler Reid toured above Hurricane Ridge on Tuesday and reported about 1-2 feet of wet snow with up to 3 feet in drifts near ridges. There were numerous recent small loose wet avalanches seen on all aspects with a few larger avalanches. Avalanches ran into ares with little or now snow cover.
Loose wet avalanche debris size 2 on Tuesday, March 17th, above the tunnels on road to Hurricane Ridge. Photo by Tyler Reid.
Avalanche Problems
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: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
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.
Elevations: Alpine.
Likelihood: Unlikely
Expected Size: 1 - 1