Avalanche Forecast
Regions: Olympics.
Stormy conditions will create very dangerous avalanche conditions on Sunday. Identify and avoid avalanche terrain including traveling below avalanche paths connected to higher terrain.
Detailed Forecast
Another round of significant precipitation and wind are expected in the Olympics Sunday. High snowfall rates, significant snow loading, moderate to intense wind transported snow, and a slight warming trend will combine to create very dangerous avalanche conditions. Expect avalanche danger to increase throughout the day.
Sensitive wind and storm slabs developed over the last several days and will continue to grow in size and become more reactive. Extra caution should be taken when traveling Sunday. Pay attention to terrain around you and avoid traveling in the tracks and runouts of avalanche paths. Natural avalanches are expected during the day, especially above treeline.
Snowpack Discussion
A stormy and windy period, beginning Wednesday and extending into the weekend, deposited over 2 feet of snow in the Hurricane Ridge area. Moderate to strong southerly winds redistributed the surface snow forming wind slabs on lee slopes near and above treeline.
New snow is bonding well to the most recent 1/16 crust layer. Currently there are no layers of concern below this most recent crust.
Observations from this region are limited. A high degree of uncertainty exists in this area.
The height of snow across the terrain is quite variable with little snow in many areas below treeline. Numerous obstacles still exist at all elevations.
Observations
NWAC observer Matt Schonwald traveled in the Hurricane Ridge terrain Thursday, Jan 18. Matt found right side up new snow bonding well to the underlying old snow surface. In wind exposed terrain however, winds Thursday were actively transporting new snow and building sensitive slab layers.
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, Treeline.
Likelihood: Very Likely
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: All elevations.
Likelihood: Likely
Expected Size: 1 - 1