Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

The likelihood of triggering a slab avalanche varies depending on where you travel Saturday. Identify and avoid steep slopes holding wind drifted snow below ridgelines, on convex rolls and unsupported terrain above and around cliffs. Look for wind slabs where you don’t normally see them as well as the usual locations.

Avalanche problems

  • Wind Slabs

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

    Wind affected snow abounds at all elevations in West South but the size, extent, and reactivity of wind slabs less of an issue in most areas.  You are more likely to find a triggerable wind slab around Paradise where more snow fell in the latest storm. The danger is lower in areas like Crystal which received notably less snow. 

    In the past week the wind blew from all over the compass so don't rely on cornices and other clues that show the usual directions of wind loading. Areas of smooth continuous snow should be your first observation to identify areas of wind slab. You can find test slopes and kick or stomp on other wind drifted features to see if wind slabs might be reactive in the immediate area. Hand pits can help with this as well. It should also be easy enough to just navigate around the steepest, smoothest, wind loaded start zones on more variable, scoured snow. Doing this will sharply reduce the risk the triggering a slab avalanche.

    (2/23/2023)

    A skier was caught and carried in this small wind slab on Thursday in Snoqualmie Pass.  The crown is visible in the narrow chute above tracks and debris. It was triggered while ascending. SW aspect at 5300'.

    Photo: NWAC Public Obs

Avalanche Discussion

Clouds and stronger winds ahead of the next storm will take longer to move south into the zone. Be ready to see some more sun and warmer temperatures. While wet avalanches are not first on the list of hazards for Saturday they should still be on your radar, especially during the first half of the day.  Look for rollerballs and other signs of instability like small avalanches. Keep an eye on steep terrain overhead as the day heats up and pull back if you see more activity than anticipated.

Reported avalanche activity in West South was limited to a few small wind slabs and a single large natural avalanche at White Pass. Details are sparse but it appears to be cornice triggered slab at 6600' on the northeast aspect of Hogback Mt. Timing is estimated as having occurred on Wednesday or Thursday due to a partly filled-in crown and bed surface. Also, a person was caught, carried, and injured in a wind slab avalanche above Snow Lake in Snoqualmie Pass. 

An NWAC Forecaster in Government Meadows (Greenwater) found lots of wind affected snow but firm and unreactive wind slabs . Surface hoar and facets were found at the snow surface at all elevations. These weak grains might even survive on shaded aspects and get buried by the next round of wind and storm slabs. A firm supportable crust was found at lower elevations with soft, settled snow in sheltered areas above 4800'.  An observer at Crystal found widespread wind affected snow on all aspects and elevations. Isolated pockets of shallow wind slab were reactive but didn't seem to present much of a hazard.

Avalanche activity should be limited to new snow and wind slabs above the recent rain crust/refreezing wet snow. Large avalanches breaking into deeper layers could occur with a big trigger like a cornice fall or a smaller avalanche.

 

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