Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

You can easily trigger slab avalanches on wind drifted slopes near and above treeline.  Use caution on all slopes steeper than 35 degrees, as you may also be able to trigger avalanches at lower elevations. Dangerous conditions have been brought on by a potent winter storm that will deliver strong to extreme winds with 6-8" of snow near the Cascade crest by Monday. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    The safest option is to stick to wind-sheltered slopes below treeline. Stay off of wind-loaded, leeward slopes that are 35 degrees and steeper. Steer around drifts, wind features, and convex rollovers. Look for signs of instability such as shooting cracks, blowing snow, and fresh avalanches. Very strong, westerly winds may build slabs further downslope than usual. You may be able to trigger wind slab avalanches below treeline on slopes that are exposed to wind near divides at the Cascade crest. 

    The strong west winds will add to existing cornices. Give cornices plenty of room when traveling on ridges and stay out from under them.  Travelers are surprised every season when cornices break further back than they expect. 

    (3/28/2021) Shallow drifts formed with strong westerly winds on the afternoon of 3/28. Gemini Pass, 5,000ft.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Wet loose avalanches involving the new snow may be possible in the afternoon on steep, sun-exposed slopes. Look for indicators of wet activity such as moist surface snow, rollerballs, and other small fan-shaped avalanches. The potential size of loose wet slides will increase where you find more recent snow especially as you go further west in the zone. While loose avalanches are predictable, they can be dangerous in very steep terrain or near terrain traps. 

Avalanche Discussion

A strong winter storm is impacting the area. The storm brought heavy snowfall rates late on Sunday with strong to extreme westerly winds. Winds gusted to 70mph on Dirty Face and over 100mph at Mission Ridge. While snowfall should slow by Monday morning, winds may keep transporting snow near and above treeline. As typical, areas closer to the Cascade crest will receive the most snow and will have the most elevated avalanche danger. Convergence may bring snow totals of up to 10 inches to the mountains between the Icicle and Chiwawa drainages.

A crust and adjacent weak layer formed in mid-January can still be found about 2-6 feet below the surface throughout most of the zone.  Several different avalanche cycles released down to this interface, with the last cycle producing avalanches up to size D4.  Avalanches on the mid-Jan crust/facet layer are now unlikely with the last one reported on March 1st.  We're watching the upcoming weather pattern for major warm-ups or storm events to see when and if these deeper layers will be tested again. The most suspect areas for deep persistent slabs are shallow, rocky, and unsupported slopes, especially where overhead cornice fall could trigger avalanches.w

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