Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You may still be able to trigger avalanches above treeline where westerly winds and heavy snow formed drifts on Saturday. Use caution at upper elevations and consider that older drifts may now be blanketed with more recent snow. Continue to assess more deeply buried week layers.

Problemi valanghivi

  • Wind Slabs

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

    You may still be able to trigger avalanches on leeward slopes 35 degrees and steeper above treeline. Use caution on slopes that may have been wind-loaded from westerly winds on the 18th or may have developed shallow slabs on Monday. More recent snow could be covering the drifts, making it difficult to assess the wind-loading patterns or identify slopes of concern. It's becoming difficult to trigger avalanches near treeline, but it's still worth keeping this problem in mind there.  Approach the upper elevations with an assessment mindset.  

     

    (12/19/2021)

    A crown from an avalanche (size D2) near Stevens Pass. This ran on 12/18 in wind affected terrain. Above treeline, NW, Chiwaukum range

    Photo: Matt Primomo

Avalanche Discussion

About 16-18" of snow accumulated during a potent storm on Saturday. Observers reported a widespread cycle of avalanches (up to size D2.5) in the recent snow at all elevations. Observers reported avalanches in the vicinity of the Hairpin Valley running to valley bottom, up to size D2.5, and some that crossed the closed highway. Smaller avalanches were reported from Delancey Ridge and Cutthroat Lake areas. At lower elevations and wind-sheltered terrain, the storm interfaces are bonding well and the snow has been stabilizing. Steep sun-exposed slopes may have formed a thin crust on Sunday.

The best that we know from limited information, the early December crust was not involved with the recent avalanche cycle. Observers continue to report test results that indicate the potential for propagation and triggered avalanches. While it may slowly become less of a concern, it's worth checking it out if you're going to upper elevations or areas outside of the top of Washington Pass. Observations are still limited. In Canada, the early December crust has been responsible for numerous very large and surprising avalanches. 

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