Avalanche Forecast
Regions: Olympics.
A significant reset of the snowpack has occurred this week, following rain and a re-freezing snow surface. Expect new unstable wind slabs to build by Saturday above treeline and a wet and slowly refreezing snowpack at lower elevations. Expect a significant increase in danger with elevation, so careful snowpack evaluation is essential.
Detailed Forecast
A low pressure system is tracking towards the central Washington coast from the SW, expected to move inland across the Olympics Friday night. This system should spread increasing precipitation, strong winds and rising snow levels late Friday through early Saturday. The peak in winds, snow levels and precipitation are expected Friday night into early Saturday morning. Significant cooling, diminishing showers and winds are expected through the day Saturday.
The biggest factor affecting Saturday's avalanche forecast confidence will be how much precipitation is received overnight and to what elevation the rain/snow line reached.
In the Hurricane Ridge area, new wind slabs are likely to have built on NW to SE aspects, mainly above treeline. But watch for firmer wind transported snow on other aspects, especially in areas of complex terrain.
At lower elevations, rain Friday night should leave a wet and slowly refreezing snowpack with shallow new snow accumulation expected Saturday. Small loose wet avalanche conditions are most likely to persist at lower elevations, especially if the cooling is delayed early Saturday. Watch for surface wet snow deeper than a few inches, rollerballs or increasing small natural releases.
Although the likelihood of wet slab or glides avalanches has greatly decreased with the recent re-freeze, these avalanche problems may reemerge following the warm and wet weather Friday night. Continue to avoid unsupported slopes where you know there is a smooth underlying surface, or slopes with glide cracks.
It is always a good plan to travel well back from ridges, suspected of cornice formation, or on steep slopes below cornices.
Remember to re-evaluate or change plans if local conditions vary from forecast conditions.
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Snowpack Discussion
Weather and Snowpack
The first week or so of March was very cool and snowy. It looks like Hurricane had about 40-50 inches of snowfall during this period.
A strong frontal system brought increasing precipitation, winds and warming trend to the Olympics and Cascades on Thursday 3/9. On Thursday night rain fell  up to about 5000-5500 feet in the Olympics. Natural and skier triggered avalanches were reported at Hurricane on Friday 3/10.Â
Moist W-SW flow and a stalled frontal boundary have produced periods of moderate to occasionally heavy rainfall at most locations throughout the Olympics and the west slopes of the Cascades on Monday through Tuesday. About a foot of snowpack consolidation was also seen at Hurricane in the past week.
The past week of weather has done a reset of the snowpack in the Olympics and along the Cascade west slopes. As of Friday, only light amounts of new snow exist over a firm, consolidated, stabilized snowpack.
Recent Observations
No recent observations.
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, North West.
Elevations: Alpine.
Likelihood: Likely
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.
Elevations: Treeline, Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1