Bulletin d’avalanche

Olympics

Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

An incoming storm will maintain dangerous avalanche conditions at mid and upper elevations Sunday.   Avalanches will be deeper and more consequential on lee slopes near and below ridgelines where winds continue to drift snow.  Shooting cracks or whumpfing collapses are clear signs to avoid nearby avalanche terrain.  

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    We've had over 2 feet of snow over the last few days in the Hurricane Ridge area.  Winds and snowfall are expected to increase once again during the day on Sunday with a winter-like storm bearing down on the region Sunday night.  Slabs will be deeper and more dangerous if they step down to storm layers buried earlier in the storm cycle or even to the new/old snow interface from last Thursday.  On Saturday, NPS rangers reported whumpfing and shooting cracks on a low angle North aspect near treeline.  The interface was likely the 3/18 pre-storm layer.  S-SW winds have drifted recent storm snow onto W-N-E aspects.  Avoid slopes steeper than 35 degrees, especially those at upper elevations capable of producing large avalanches.   

    While sticking to lower angle and treed terrain will serve you well,  your awareness of potential overhead hazard is also key for safe travel.  If you're traveling below open slopes with large overhanging cornices, put extra distance between you and where large avalanches can run or stop.  If traveling along ridgelines, expect poor visibility as the day wears on, and make sure to stay well back from the edge.  Travelers are surprised every winter when cornices break further back than they expect. 

    (3/12/2021) Example of the type of terrain capable of producing large avalanches in the Hurricane Ridge area. Photo: Sam Luthy

Avalanche Discussion

It just keeps snowing in the Olympics with the Hurricane Ridge area reporting roughly 2' of snow since Thursday night with periods of moderate to strong southerly winds drifting snowfall onto the same lee slopes.  Recent storm layers will be tested as snow and winds ramp up during the day in advance of heavier precipitation expected Sunday night.

Recent snow may not have bonded well to the previous 3/18 snow surface. On southerly aspects, this interface is most likely a crust. On northerly aspects, this interface may be weak faceted snow grains.  On Saturday, NPS staff experienced a whumpfing collapse and a shooting crack from a snow pit on a north aspect near treeline.  The depth (~3') likely represents drifted storm snow that has accumulated since Thursday night.  While this is only one piece of information, it suggests the ingredients may be in place for you to trigger a large avalanche on open slopes with wind drifted snow near and above treeline.  Play it conservative on Sunday, choosing lower angle terrain not connected to large slopes above.   

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.

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