Avalanche Forecast
Regions: Olympics.
A mixed bag of ugly snow conditions and a considerable avalanche danger in the near and above treeline elevation bands is expected Friday. Careful snowpack evaluation will be needed on Friday.
Detailed Forecast
The next weather system will move strongly to the Olympics and north Cascades Friday late morning and spread to the rest of the Cascades by Friday evening with fairly high snow levels.
AÂ broad brush will be applied to the avalanche forecast for Friday. Expect a mixed bag of ugly snow conditions and a considerable avalanche danger in the near and above treeline elevation bands at Hurricane Ridge.
Recent snow will be available for activation by rain and warm temperatures. Watch for surface wet snow deeper than a few inches and pinwheels or small natural loose wet avalanches that usually precede large loose wet avalanches.
Rain will load old wind slab and possibly cause wet slab avalanches in the near and above tree line bands.
But new snow and cooler temperatures should be seen by Saturday.
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Snowpack Discussion
Heavy rain fell in the Olympics January 27th-28th with over 2 inches of rain recorded at the NWAC station at Hurricane Ridge.
The "20th of June" path released as a wet slab during the rain and warmth January 27th. Photo: January 29th by Matt Schonwald.
A strong occluded front with strong winds crossed the Northwest last Friday and Saturday. Hurricane Ridge had about 14 inches snowfall.
NWAC pro-observer, Matt Schonwald visited Hurricane on Friday, January 29th and found rapidly building wind slab and extensive loading on lee slopes in all 3 elevation bands. New cornices were sensitive to triggering but still relatively small.Â
Cool, benign weather followed Sunday through Tuesday. A sun crust formed on many solar slopes and surface hoar was seen on many non-solar slopes.
A cold front crossed the Northwest on Wednesday. A warm front is causing more snow mainly in the south Cascades today. Hurricane Ridge for the 2 days ending Friday morning will probably have only about 4 inches increasing damp or wet snow.
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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: All elevations.
Likelihood: Likely
Expected Size: 1 - 1
Wet Slabs
Release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slab avalanches can be very destructive.
Avoid terrain where and when you suspect Wet Slab avalanche activity. Give yourself a wide safety buffer to handle the uncertainty
A Wet Slab avalanche. In this avalanche, the meltwater pooled above a dusty layer of snow. Note all the smaller wet loose avalanches to either side.
Wet slabs occur when there is liquid water in the snowpack, and can release during the first few days of a warming period. Travel early in the day and avoiding avalanche paths when you see pinwheels, roller balls, loose wet avalanches, and during rain-on-snow events.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1