Avalanche Forecast
Regions: Cascades - North West.
Dangerous avalanche conditions will persist Thursday, especially in terrain receiving wind transported snow. Avoid steep open slopes. Give safe margins near and below growing cornices. Storm snow is very deep! Tree-well and snow immersion hazards are very dangerous, so keep communication with your partner at all times. Storm layers will take extra time to stabilize.
Detailed Forecast
Moderate rain and snow late Wednesday should taper to light to moderate showers with a cooling trend overnight Wednesday and Thursday. Â
Increasing crest level winds are expected Wednesday night and Thursday.Â
The avalanche danger will lower slightly Thursday, but it will take time for these deep storm slab layers to stabilize, mainly at lower elevations with little wind exposure. Near and above treeline, strong winds should continue to build wind slabs along lee slopes below ridges and exposed open terrain.
Dangerous avalanche conditions will persist due to the likelihood for triggering a large and potentially deadly avalanche. Recent storm and wind slabs will require time to heal, so be patient and match your terrain selection appropriately, namely very conservative.
Significantly transformed snow conditions have taken place during this extended storm cycle. Tree-well and snow immersion hazards are very dangerous, so keep communication with your partner at all times.
Snowpack Discussion
An extended storm cycle continues. The Mt Baker area has received over 7 inches of water equivalent and nearly 100 inches of snowfall in the past 7 days as of Wednesday evening! The snowdepth alone has increased by 5 feet in the past week.
Warming early Wednesday, along with heavy snowfall and strong winds led to a widespread natural avalanche cycle. Slab avalanches of 2 ft or more were common and traveled long distances. Avalanches were releasing in terrain well below treeline leading to an update and issuance of an avalanche warning in this zone.
Dense storm slabs built quickly early Wednesday.Â
Below the recent 2 ft of storm snow, more than 5 feet of gradually settling snow sits above the most recent melt-freeze crust - it is very deep out there!Â
Poor visibility and frequent storm conditions have limited observations above treeline during this period.Â
Observations:Â
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 sensitive to ski trigger with slabs of 2 ft or more running long distances. Â
On Tuesday, NWAC Pro Observer Lee Lazara was in the Baker Lake area in below treeline terrain where he experienced significantly less snow accumulated above the recent crust (approximately 2') relative to Bagley Lakes. New storm instabilities had not yet developed in this location. There were various resistant planar interfaces within the storm snow from the past several days and the interface with the weak wet snow above a January 18th crust yielded hard test results.
On Tuesday, Mt. Baker Pro Patrol reported that a large avalanche was heard in the vicinity of Mt. Shuksan.
An avalanche professional in the Glacier Creek area reported little wind and occasionally heavy snow showers on Monday. A reactive storm layer within the most recent storm snow allowed storm slabs of 6-10" to be easily triggered on all aspects up to 5600'. A few natural storm slabs were observed as well.Â
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: 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: North, North East, East, South East, West, North West.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2