Avalanche Forecast
Regions: Cascades - North West.
Significant snow accumulation throughout this storm cycle has developed conditions ripe for very large and destructive avalanches. Avoid terrain where avalanches may start, run, and stop until we exit this storm cycle. Avalanches may entrain significant amounts of snow and travel far into their runouts effecting traditional travel routes. Numerous hazards will challenge your ability to travel safely in the mountains Saturday.
Detailed Forecast
The avalanche danger will increase throughout the day Saturday. Warming air temperatures, an increase in wind, and light to moderate showers will combine to create very dangerous avalanche conditions. Very large and destructive avalanches may occur. These slides can travel significant distances that extend far into the runouts.
Avoid areas where avalanches can start, run, and stop including terrain above you. Use very wide safety margins if traveling in the backcountry Saturday. Avalanches may overrun traditional safer locations.
Cornices have grown extremely large throughout this storm cycle. Limit your exposure to overhead cornice hazard.Â
Snow conditions have changed significantly during this stormy period. Tree-well and snow immersion hazards are very dangerous. Keep communication with your partner at all times.
Snowpack Discussion
Snow continues to pile up in the Mt Baker backcountry. Generally 4 to 6 feet of snow now sits atop the most recent crust. Numerous subtle layers exist within the storm snow but they are generally gaining strength.
As of Friday afternoon, loose surface snow was reported around the Baker area along with shallow storm slabs.
Wind transportation of the most recent snow has been limited to higher elevations and exposed features in the terrain.
Poor visibility and frequent storm conditions have limited observations above treeline during this period.
Observations
NWAC Observer Lee Lazara was in the Glacier Creek area Friday. Lee reported shallow sensitive storm slabs even in thicker trees below treeline. Four feet of snow was observed over the 1/18 crust.
Wednesday, Mt Baker Pro Patrol reported a very active avalanche cycle was ongoing. There were large natural avalanches releasing from Shuksan Arm and all avalanche paths in area were sensitive to ski triggering with slabs of 2 ft or more running long distances.
Avalanche Problems
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
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: Alpine, Treeline.
Likelihood: Very Likely
Expected Size: 1 - 2