Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

It will be easy to trigger avalanches at upper elevations in fresh wind-drifted snow. You may be able to trigger large and very dangerous avalanches on an older layer.  Default to lower angle slopes to reduce your exposure to the danger.  Be mindful of changing conditions and give yourself some space from steep, upper-elevation wind-drifted areas.  

Problemi valanghivi

  • Wind Slabs

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

    Fresh wind-drifted slabs may be easy to trigger just below ridges, especially if they sit on weak snow surfaces that got buried on Saturday. You can find these wind slabs on the down-wind side of ridges, below cornices, and peppered in the alpine.  Give yourself some space from steep, convex slopes and pillows of snow on the lee-side of ridges. Avalanches may be bigger and easier to trigger above treeline.

    If you find yourself traveling at higher elevations on shaded slopes ( N-NE- E), consider the consequence of a wind slab stepping down into a deeper buried weak layer and producing a much larger, destructive avalanche. 

    (12/3/2022)

    Actively blowing snow, freshly building sharp cornices, and textured surfaces. All easy-to-identify signs of wind-loading. Use visual clues like this to help you identify slopes of concern on Saturday. 

    Photo: Dallas Glass

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–2.5

    The best way to handle the uncertainty of these dangerous avalanches is to put a wide buffer between where you travel and large steep features. You can reduce your exposure by traveling on ridges or slopes less than 35 degrees. Surface hoar buried on January 4th has been the source of a number of avalanches. You can find the weak layer in sheltered, open terrain near or possibly above treeline. The distribution has proven to be spotty and not everywhere. Use snow pits to identify this layer 1-2ft below the surface and look for a thin gray line of feathery, buried surface hoar grains.  

    (1/19/2023)

    Large avalanche on a layer of buried surface hoar. NE at 6,200ft on Jim Hill. The crown was 1-2ft deep.

    Photo: Ryan Minton

Avalanche Discussion

On Saturday Katie Warren and Brooke Maushund investigated a very widely propagating avalanche in Turnpike creek in the Ingalls watershed. We believe that the natural avalanche occurred during the storm of the 13h or 14th. While the avalanche is now older, it was a good indicator that the January 4th surface hoar has been active in this part of the zone. 

On Friday, Joe Dellaporta and I traveled into the Blewett Pass area. The calm and clear nights have caused snow surfaces to become weak and sugary.  In most locations, we traveled we observed either surface hoar or near-surface facets sitting above the MLK rain crust.  Keep this on your mind as you travel, since it could be tomorrow's buried weak layer. 

 

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