Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

At the start of the day you could trigger small wind slabs, but expect the size and distribution of the slabs to increase as the day progresses. You'll be able to see wind actively redistributing snow, so pay attention to where it falls and steer clear of those areas or other notably wind loaded locations if they're on steep slopes. It's important to assess snowfall and wind distribution as you travel because conditions will likely vary depending on where you are in the zone, meaning avalanche danger could vary. 

Avalanche problems

  • Wind Slabs

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

    Small human triggered wind slab avalanches occurred in neighboring zones in the last few days. Sunday may start like this, but by early afternoon or sooner you can expect to see an increace in avalanche size and reactivity. You're likely to encounter active wind loading, with snow blowing across slopes and depositing into thick drifts. These are obvious locations to avoid, if they are on steep slopes.

    Use bullseye clues, or red flags as indicators throughout your travels. In the afternoon we expect at least two of the red flags will already be present - heavy snowfall (at least an inch an hour), and wind. Identifying other clues such as long shooting cracks, whumphing, or recent avalanches are just icing on the cake, all pointing to steering clear of wind loaded slopes greater than 35 degrees.

    Depending on the wind and snowfall amounts, some locations by the end of the day, wind loaded or not, could hold enough snow that you could trigger a slab avalanche on steep slopes. This is an important day to evaluate the snow conditions and terrain before you get out on it, determining how much new snow and wind redistribution there's been, before travelig in steep terrain. When in doubt, stick to lower angle slopes. 

    (2/18/2023)

    Classic signs of wind loading  found in the neighboring Snoqualmie zone on Saturday. This may be like what you see on Sunday. 

    Photo: Dallas Glass

Avalanche Discussion

You could trigger small dry loose snow avalanches on less wind-affected steep slopes on Sunday. Sluffs shouldn't grow too large - but keep an eye on how much snow is moving around or behind you if venturing into steeper terrain.

Throughout the zone around half an inch of water may fall by Sunday evening, before it really intensifies overnight. Wind will continue to increase through the night as well. Avalanche danger will rapidly increase moving into Monday, where storm totals could reach 2 or more inches of water, or 2+ feet of snow, by the end of the day. 

In neighboring zones we've infrequently been getting reports of large avalanches, human triggered, failing on slightly weak layers near crusts, likely buried 3 or more feet below the snow's surface.  The last avalanches failed about a week ago on these layers. There's a very small chance that this layer may become reactive again with all the new weight added with this storm. 

Regions covered