Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

You may still trigger a lingering pocket of wind-loaded snow, particularly in very steep, rocky terrain at upper elevations. Human triggered slides occurred in this zone each of the last several days. Elsewhere expect generally safe avalanche conditions.

Avalanche problems

  • Wind Slabs

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

    These wind slabs are a few days old and becoming very stubborn. However, each day we receive a report of another human-triggered wind slab avalanche. While most slopes probably won’t release, don’t totally write this problem off. 

    It may be impossible to tell if any particular wind-loaded pocket will fail. Since you can’t “assess” it, set yourself up for success by avoiding these frim pillow-like slabs on very steep slopes and unsupported terrain that end in traps like rocks, cliffs, gullies, or creeks. 

    So far, all recorded avalanches have been on very steep or rocky slopes and typically produce slides 10-12 inches deep.

    (2/23/2024)

    A recent natural wind slab avalanche. This slide likely triggered when snow shed from the rocks above. SE, 6900ft

    Photo: Dallas Glass

Avalanche Discussion

Saturday will be the proverbial “calm before the storm” in the West South zone. You may see a few snowflakes later in the afternoon, but they won’t amount to much. Instead, the cloudy, cool weather should significantly reduce the avalanche hazard in all but a few isolated pockets of wind-loaded terrain. 

Another human triggered wind slab was reported from the Crystal area Friday. This slide occurred on a NW aspect at 6800ft. Additionally, an NWAC forecaster at Mt Rainier recorded 6 recent natural wind slabs that likely failed Wednesday or Thursday. Each of these was triggered by a wet loose, cornice, or shedding snow (E-SE, 5900-6900ft).

Mostly clear skies Friday evening should allow wet snow surfaces to freeze solid and from a new crust on sunny aspects. This will pretty much put an end to avalanche concerns on these slopes. The clear skies will also allow a fresh batch of surface hoar to form. Surface hoar on Friday survived on shaded aspects and may just grow larger before the clouds roll in. Savvy travelers will pay attention to what’s on top of the snow on Saturday. There’s an old avalanche adage, “today’s surface is tomorrow’s weak layer.” That could be particularly true with this storm. As precipitation begins Saturday afternoon/evening, it will bury these potential weaklayers, and they may produce slides on Sunday. 

We’ve been tracking the upper snowpack for weeks. While we haven’t seen many avalanches failing on older snow layers, a weak structure exists not just in the West South but across all of NWAC’s forecast areas. On more southerly aspects, there is less snow and generally stronger upper snowpack over the Early February Crust (EFC). However, on more shaded slopes, several layers (2/11, 2/14, 2/19) exist that may hold facets, buried surface hoar, or crusts. Then there are facets just on top of the EFC. We don’t expect these layers to be an issue on Saturday, but they are certainly on our minds as we enter a stormy week. 

Aside from avalanche concerns, you may encounter a few travel hazards. Breakable crust, frozen rollerballs, small piles of debris, and open creeks could make even simple routes much more “sporty.” 

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