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Avalanche Forecast

Archived

Jan 24th, 2018–Jan 25th, 2018

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

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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.  

Increasing crest level winds are expected Wednesday night and Thursday. 

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. 

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! 

Poor visibility and frequent storm conditions have limited observations above treeline during this period. 

Observations: 

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.  

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. 

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). 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.

Wind Slabs

Wind Slab avalanches are the 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.