Avalanche Forecast
Regions: Cascades - North West.
A very stormy day on Sunday will create very dangerous avalanche conditions with large and destructive avalanches expected. Identify and avoid all avalanche terrain including places where avalanches can run and stop. Avalanches originating at higher elevations may entrain large amounts of snow and travel significant distances.
Detailed Forecast
High precipitation rates, significant storm totals, moderate to intense wind transportation of snow, and a slight warming trend late Saturday night through Sunday morning will combine forces to create very dangerous avalanche conditions. Natural avalanches are expected at all elevations. Some of these avalanches may entrain significant amounts of recent snow and travel far into their runout zones.
Identify and avoid all avalanche terrain. Be aware of terrain above you where avalanches originating at higher elevations may travel to your current location.
Deep snow exists throughout the Mt Baker area. Snow immersion and tree-well hazards continue to increase. Maintain constant communication with your travel partners.
Snowpack Discussion
Very dangerous avalanche conditions have developed and continue to increase due to significant precipitation and wind in the Mt Baker area. Avoid areas where avalanches can start, run, and stop. Pay attention to terrain above you as large and very large avalanches are expected and may entrain significant amounts of snow.
A stormy and windy period over the last several days has deposited nearly 5 inches of water in the Mt Baker area as of Saturday afternoon. In most locations this means several feet of new snow sits atop the most recent crust layer. A general cooling trend has allowed most of the snow to form a favorable hardness profile.
Winds throughout the storm cycle have formed sensitive wind slabs on lee slopes. Observations indicate wind slabs up to 3 feet thick in some areas.
Difficult travel conditions and very limited visibility has minimized observations from above treeline terrain. Expect deeper storm snow and significant wind redistribution.
Below the most recent crust there are no layers of concern.
Observations
North
Saturday Mt Baker ski patrol reported generally soft surface snow conditions with limited slab development in sheltered areas. While winds were decreasing, wind transportation from Friday night was observed near treeline.
On Friday, NWAC professionals traveled to near treeline in the Baker backcountry. They avoided exposed terrain above treeline due to potential for large and dangerous wind slabs. Active wind transport and new snow occurring throughout the day redistributed the deep storm snow. There was evidence of a large wind slab avalanche near treeline on a N-facing slope.
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: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2
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: Very Likely
Expected Size: 1 - 1