Bollettino valanghe

East Slopes South

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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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You can trigger a sizable avalanche that breaks in fresh wind drifted snow on Monday.  You will find the largest wind slabs lurking below cornices, adjacent to ridgelines, and scattered through the alpine.  Steer around steep slopes that show recent signs of wind loading. 

 

Problemi valanghivi

  • Wind Slabs

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

    More new snow (.25-50 swe) paired with moderate to strong S-SW winds will continue to build slabs of wind drifted snow.  After yesterday's snow totals ( 6-8 in), steady southerly winds, and the forecasted precipitation for Monday - these slabs are likely growing in size and distribution across the terrain. It may be possible for you to trigger a wind slab that breaks 1-3 ft deep that fails on a crust. Observations from adjacent zones point at weak, faceted snow lurking near a melt-freeze crust that formed over New Years. 

    You will most commonly find these wind slabs on the lee-side of ridges, under cornices, and scattered across mid and upper elevation slopes. These slabs may be pushed further down slopes than usual due to strong wind speeds.  

    Monday will be a good day to take a step back and steer around steep, wind loaded slopes greater than 35 degrees.  Use visual clues to help you identify these wind drifted areas.  Look for where the wind is blowing the snow, wind textured surfaces, and pillow-like slabs forming to help you identify areas to avoid.  

    (12/30/2022)

    Use visual clues to help you identify wind loaded slopes. In this case, cornices often are a great indicator of a wind drifted slope beneath. 

    Photo: Joe Dellaporta

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    With new snow and warm lower elevation temperatures, you may find small wet loose avalanches releasing on steep slopes below treeline. If you start observing rollerballs or pinwheels, steer around steep slopes since larger wet loose avalanches may soon follow. 

     

    (11/8/2022)

    Rollerballs and pinwheels are an indicator of the snow surface becoming moist. 

    Photo: Andy Harrington

Avalanche Discussion

This storm pattern that we are currently in is certainly favoring the east-south.  Over the last 24 hours, snotels ( green lake & lost horse)  across the zone are reading 6-8 inches of new snow.  

On Sunday, the Mission Ridge Pro Patrol in the east central zone, triggered wind slabs under cornices that failed 12-16 inches deep near their ridgeline. Slabs are likely growing to similar size at upper elevations in the east-south.

A complex snowpack exists in many areas of the eastern Cascades with weak faceted snow and surface hoar potentially buried on sheltered northern aspects, and steep southerly aspects may have a slick melt freeze crust underlying the most recent storm snow. It will be essential to monitor how the new snow reacts as you travel. Slight variations in aspect could have very different avalanche conditions. Use quick hand pits and small test slopes to observe how well the new snow bonds to underlying surfaces. If you find reg flags such as shooting cracks, collapsing, recent avalanches, or new snow that slides easily, dial back your terrain choices to low angle slope.

If you get out into the East-South, let us know what you see by submitting a public observation. 

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