Avalanche Forecast
Regions: Olympics.
Mostly small, shallow areas of new wind and storm slab will be possible in the near and above treeline on Saturday. These avalanche problems would be greater if there is more new snow than expected. Watch for signs of loose wet avalanches mainly below treeline.
Detailed Forecast
Rain or snow should change to showers Friday night with lower snow levels. Partly cloudy weather Saturday morning should give way to some sun by Saturday afternoon at Hurricane.
This weather should bring a couple to a few inches of snow near and above treeline with a cooling trend. The cooling trend with rain changing to snow mainly in the near and above treeline should help bond new snow to previous snow.
New small areas of mostly shallow wind slab will be possible on isolated lee slopes. This should be mainly N to E slopes near and above treeline. Watch for firmer wind transported snow.
Small areas of shallow storm slab will also be possible if any areas receive a few inches of rapidly accumulating snowfall.
These avalanche problems would be greater if there is more new snow than expected.
Possible, mostly small, loose wet avalanches also will remain a problem in the below treeline on Saturday.
Snowpack Discussion
Weather and Snowpack
The last snowfall occurred late last week when about a foot of snow fell by last Saturday. Some cornices and wind slabs formed during this period but recent warm weather and sunshine have likely settled and stabilized wind slabs.
Springlike weather under high pressure Wednesday and Thursday caused abundant sunshine with temperatures climbing into the upper 40's Thursday afternoon. This weather has allowed for melt-freeze crust formation overnight and varying amounts of wet surface snow depending on slope aspect.Â
Recent Observations
NWAC pro-observer Matt Schonwald was at Hurricane Ridge today Friday February 26th and found a pretty uniform stable snow pack due to warm weather. He generally found rounded grains and consolidated snow on solar slopes and moist snow on N slopes. A small area of possible wind slab was seen on a north slope called Lisa Jane near the visitor center but it was unsafe to test the slope. Clouds prevented the development of loose wet snow.
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.
Elevations: Alpine, Treeline.
Likelihood: Possible
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: 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.
Elevations: Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1