Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dangerous conditions continue after significant snowfall and wind added a heavy load this weekend and stressed weak layers of snow.  Stay far away from and well out from under wind-loaded, open terrain 35 degrees and steeper. Consider avoiding avalanche terrain at upper elevations where you can trigger very large and destructive avalanches that could break widely across slopes.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Watch for wind-stiffened snow, drifting, and actively blowing snow. Avoid leeward slopes where westerly wind has deposited thick slabs over the past 5 days. Avalanches will be bigger and easier to trigger above treeline. Any slide could break into older weak layers of snow causing a very large and destructive deep persistent slab avalanche. Use caution near cornices and the edge of ridgelines. You may be able to trigger wind features and cornices very easily.  You can use small, inconsequential slopes to check if the storm snow slides or cracks easily. In wind-sheltered terrain, you could trigger small loose dry avalanches on slopes near 40 degrees.

    (2/8/2021) Cornices and wind drifting on Mt. Snoqualmie in the neighboring Snoqualmie Pass zone on Monday.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3

    Deep persistent slab avalanches are difficult to manage and can catch even experienced travelers by surprise. The best way to stay safe is to avoid large, open slopes 35 degrees and steeper especially where wind loading has occurred. Put a large buffer of terrain between where you travel and all avalanche paths. Make sure to regroup and stop only in truly safe terrain, well away from and out from under steeper slopes. You may be able to trigger these avalanches from a long distance away. While these avalanches may be less likely below treeline, there's uncertainty and the snowpack structure can be found in open terrain above 4,000ft. These avalanches give little warning before releasing. To be safe, approach any slope steeper than 35 degrees with extreme caution. When in doubt, avoid avalanche terrain.

     A widespread cycle of slab avalanches ran on persistent weak layers from Friday through Sunday. Observers confirmed avalanches that broke widely and were remotely triggered on this layer, including an avalanche burial, resulting in no injuries on Jim Hill. About 3-4 feet below the surface, you can find a softer layer of weak faceted snow above or around a crust that formed in mid-January. Sudden and propagating snowpack tests on this layer can indicate the potential for an avalanche.

    (2/8/2021) A very large (D3) natural avalanche likely ran between Feb 6-7th on Sixtysix Hundred ridge in the Icicle drainage in the neighboring East Central zone. 6,600ft, ENE. Photo: Matt Primomo

Avalanche Discussion

Preliminary avalanche incident information Monday February 8th, 2021: Two snow bike riders were caught and buried by a very large avalanche in the mountains west of Salmon la Sac Sno-Park along Cle Elum Lake. One snow biker was partially buried and was able to dig himself out. The other rider was fully buried and killed by the avalanche. The avalanche occurred on a north aspect at 4400 ft in the Knox Creek drainage. This terrain lies in NWAC’s East Central forecast zone. Avalanche classification: HS-AV-R3-D3-O. 

All of us at NWAC want to extend our condolences to family, friends and the local community following this tragic event.  

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The peak of natural avalanche activity at Stevens Pass likely occurred Saturday night. Observers got glimpses of slides on Sunday and submitted a flurry of avalanches observations. A very large natural D3 avalanche likely ran on the night of the 6th on a NW aspect of Jim Hill into the Lanham Creek drainage in addition to the . There was also a report of a large natural avalanche on a southeast aspect around 5,400ft in upper Nason creek.  After avalanche mitigation on Sunday, Stevens Pass Patrol reported triggering widespread and touchy loose dry and soft slab avalanches in the recent snow along with a few slopes still breaking 3-4 feet deep to the mid-January crust.

On Friday the 5th, I observed a very large and widely propagating persistent slab avalanche in Highlands Bowl (SE at 5,600ft) outside of the boundary of Stevens Pass resort. Stevens Pass Ski Patrol remotely triggered 2ft deep avalanches while skinning on northeast aspects at 5,800ft and ran on the mid-January crust facet layer. WSDOT triggered large avalanches in both new snow, and older snow early in the morning as well. One was a D3 avalanche (big enough to break trees) and ran on the same crust. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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