Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Steep rollovers or other types of unsupported terrain above treeline are where you can trigger a fresh slab of wind drifted snow. Use planar and lower angle slopes to navigate around these features and reduce risk. Danger from slab and wet avalanches is slightly farther south in West Central.  Check the forecasts for Stevens and Snoqualmie Pass if you are traveling near those zones.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Light snowfall and moderate winds will create new slabs in the alpine. You could also see new slabs and greater danger near treeline if there is more snow or stronger winds than forecast. Anticipate more and larger slabs closer to the Cascade Crest where east winds are stronger.

    The standard toolkit to identify and evaluate wind slabs - drifting snow, wind affected surfaces, cornices, cracking, tracking changes in slab depth and stiffness, etc. - should be plenty to help you bypass steep, freshly wind loaded slopes. If you are traveling in high consequence, alpine terrain best practice would be to apply all of the above. Conditions are generally safe in terrain with no wind affect and loading. 

    An example of cornices and wind loading in Stevens Pass

     

Avalanche Discussion

Sunny mornings transitioning to afternoon showers are in the cards again for Tuesday and Wednesday. The likelihood of seeing wet avalanche activity is low but not impossible. If the sun is out and it feels warm, be on the lookout for wet avalanche activity on solar slopes.

Observers in Snoqualmie Pass reported 6-8" wind slabs and a very large avalanche that probably released during the peak of precipitation and winds with the last storm. A number of wet loose avalanches and a slab avalanche (2nd photo) were reported from Stevens Pass.

An NWAC Forecaster in West Central found a right side up, stable snowpack. Old wind slabs were unreactive and it stayed too cool to see wet loose avalanche activity. Testing produced no results at storm snow or graupel layers. No facets were found around a crust down about 4’ or at another, deeper crust.

In most areas a firm sun crust coats many slopes on the south half of the compass. Very good riding conditions are still reported from shaded and wind sheltered areas. Lots of wind affected snow is found along ridgelines.

Two cornice fall triggered slab avalanches were some of the most notable events over the weekend (obs, obs). Cornices grew large and unstable in the past month with colder temperatures, plenty of snowfall, and wind. These avalanches are a sign cornices are a hazard to backcountry travel - as in being below one or unknowingly standing on one - for the rest of the winter and spring.

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