Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

You will find wind affected snow on a variety of aspects on Monday. Identify and avoid steep terrain where the wind is building areas of dense, stiff snow. Reduce uncertainty and risk by sticking to lower angle slopes that are sheltered from the wind 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Backcountry travelers triggered a handful of wind slabs in near treeline terrain on Sunday. Though small in size they were very easy to trigger and are a bellwether of larger, more dangerous avalanches lurking in alpine terrain. On Monday moderate southeasterly winds will continue to transport abundant new snow and build fresh wind slabs.

    Large, steep, open slopes in the alpine are obvious terrain features to avoid, but also be on the lookout for unstable slabs in less intimidating terrain. Convex rolls in sparsely treed terrain, gully walls, and around rocky outcrops and cliffs are all places where you will be more likely to trigger an avalanche.

    Pay attention as you move through the terrain and look for wind slabs on uncommon aspects. For example, you can use a probe or ski pole to feel for and track deeper drifts, dig hand pits, and take advantage of test slopes as you move through the terrain. 

    (12/12/2021)

    Small (D1) skier triggered, wind slab avalanche in the West North zone on

    Sunday.

    Photo: Zack McGill - Baker Mountain Guides

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    You may be able to trigger avalanches on slopes steeper than 35 degrees in the southern end of the West Central zone.  Look for hard over soft layering or interfaces that break easily within the top 2 feet of the snowpack. Other signs of instability are recent avalanches, cracks in the snow, and test slopes that slide easily. Quick snowpack tests can be useful to assess if the snow could slide before you commit to steeper terrain.

    (12/11/2021)

    Investigating the crown of a skier triggered avalanche. This slide ran within the new snow 40cm below the surface and broke about 75 feet wide. SS-AS-R1-D1-S. 5100ft, SE, Big Chief Mtn

    Photo: Josh Hirshberg

Avalanche Discussion

Small (D1) human triggered avalanches were reported in wind loaded in the adjacent West North zone on Sunday. These avalanches were around 1’ deep, and were triggered on steep, leeward slopes. Observations from the upper elevations and surrounding terrain were again limited by very stormy conditions.

Observers near Stevens Pass reported triggering numerous small (D1) slab avalanches in steep terrain below treeline. These avalanches occurred on a range of aspects (NE, SE, S), were 1 foot deep or less, and the character and width were consistent with storm slab instabilities. On Saturday, both natural and human-triggered avalanches were reported around Stevens Pass with the bulk of these avalanches being small slab avalanches on leeward sides of ridges and wind-loaded slopes.

Additional snowfall of 3-6” is expected on Monday with moderate ridgeline winds in the morning backing off in the afternoon. If wind speeds are stronger or persist longer than expected, anticipate elevated danger and unusual loading patterns near and above treeline.

The snowpack has more than doubled since December 10th.  Many below treeline areas are seeing their first significant snowpack of the season. Although the new snow in wind sheltered areas (3 or more feet in favored locations) is well bonded both within the storm layers and to the old snow surface, sustained winds will continue to create instabilities in less sheltered areas. 

Early season hazards exist in many areas even with the fresh coat of snow. In some cases, they may pose more of a hazard as once visible stumps, boulders, creeks, etc. are now just hidden below the surface. In addition, shallowly buried objects will increase the consequences of being caught in an avalanche. You could easily get injured by being pushed into rocky terrain or trees.

Preliminary Accident Report: On Saturday morning, December 11th, an avalanche fatality occurred in the Silver Basin area of Crystal Mountain Ski Resort. See the accident summary for additional details." 

"Uphill travel reminder: Check in with your local ski area this weekend regarding terrain access and parking updates. Closed ski areas often share a similar snowpack and avalanche hazard as the surrounding backcountry. You may also encounter other hazards like active avalanche mitigation, unmarked obstacles, snowmobiles, groomers, and other heavy equipment as ski areas prepare to open. Be prepared to make your own assessments and handle emergency situations."

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