Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
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

UPDATE: Increased avalanche danger and added wind slabs a problem to reflect the most recent weather forecast guidance.

Expect new snow and strong winds to form fresh slabs at mid and upper elevations today and slowly increase the avalanche danger. Watch for blowing snow and drifts to indicate which aspects you may want to avoid. By the end of the day, some of these slabs may be close to a foot or more thick and capable of producing large avalanches.

Problemi valanghivi

  • Wind Slabs

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

    The West North zone could accumulate 6" or more of snow by the end of Sunday combined with strong southerly winds. This will likely form new wind slabs on lee slopes at mid and upper elevations. While these drifts will be shallow to start the day, they will continue to grow and could reach a foot or more thick. Blowing snow will serve as your most obvious clue for which slopes you want to avoid. If you see building cornices or drifts, steer away from nearby steep slopes. Due to the dynamic conditions of the day, expect the highest avalanche danger and potential for larger avalanches in the afternoon hours. 

    (12/18/2020) Example: Fresh wind lips remind you that winds have transported snow and loaded slopes.

Avalanche Discussion

PREVIOUS DISCUSSION FROM 3/14: Temperatures spiked on Saturday and most wet loose avalanches already ran, but stay alert if slopes remain moist on Sunday. The increased cloud cover may limit the wet snow’s ability to freeze overnight. Additionally, cloudy skies could mean the previously dry cold powder on northerly aspects might get damp, so you may see small avalanches, but that is unlikely. 

If you are considering complex north-facing terrain at higher elevations, stay alert for the odd wind slab, which may still react to your weight in isolated areas. New snow isn’t expected to accumulate much during the day, but the combination of fresh snow and wind could form small reactive wind slabs to look out for on leeward slopes. 

Cornice fall is the other notable concern. Cooling temperatures are reducing the risk, but any chance of it occurring is scary. Check out the photo of the cornice triggered avalanche from Thursday, triggering a large D2 avalanche on the wind loaded slope beneath it. A cornice could trigger a wind slab that wouldn’t react otherwise, or a deeper avalanche on large, exposed upper elevation slopes. For this reason be very wary around cornices, staying far back from their edges and limit your exposure beneath corniced ridgelines.

Travel conditions may challenge you, as you might find slick, or bumpy frozen surfaces on  southerly and low elevation slopes. You will probably also find punchy crusts, and sticky snow as well. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte