Avalanche Forecast
Regions: Olympics.
Wind slabs formed on a variety of aspects Thursday. Look for and avoid areas of wind deposited snow such as fresh cornices and snow drifts. Keep an eye on changing surface conditions as mild weather and clearing skies allow sunny slopes to develop the potential for loose wet avalanches.
Detailed Forecast
After a drippy and and cloudy start, warm air temperatures, light winds, and partially clearing skies in the afternoon will allow moist surface snow to develop on sunny slopes Saturday. Keep an eye out for signs of loose snow instability such as rollerballs and pinwheels. These can be a sign that conditions are becoming prime for loose wet avalanches.
Near and above treeline, wind slabs formed Thursday are expected to linger. While they are gaining strength, take time to identify and avoid areas where winds have deposited snow.
Despite the recent snow, early season hazards still exist. Many creek beds have still not filled in for the winter.
Snowpack Discussion
Very light precipitation and mild temperatures on Friday allowed storm snow layers to continue to gain strength. Ridge top winds continued to redistribute snow especially in the above treeline areas.
About of foot of recent snow is bonding to the most recent rain crust which exists in sheltered terrain around Hurricane Ridge. Below this rain crust, no notable layers of concern have been identified within the snowpack.
The height of snow across the terrain is quite variable with low snow in many areas below treeline. Numerous obstacles still exist at all elevations.
Observations
NPS Rangers Friday morning reported small natural loose wet avalanches visible on road cuts up to 4500 feet on the Hurricane Ridge road.
NWAC pro-observer Matt Schonwald was at Hurricane Ridge on Thursday 1/11. Matt found despite the significant storm snow, below treeline elevation band had quite variable snowcover. Around Hurricane Ridge, the east slopes had a snow depth of 2.5 feet and the west slopes had about 5 feet. Winds were actively transporting new snow near and especially above treeline, but the loading pattern was variable. Small loose wet avalanches were observed releasing in steep terrain above the road at about 4500' during gradual warming on Thursday.
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: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
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: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1