Bollettino valanghe

Olympics

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Avalanche conditions are rapidly becoming dangerous at Hurricane Ridge as a storm brings significant snow and wind. Slabs may be especially reactive if they sit above weak snow grains to propagate more widely than you expect. Avoid all slopes steeper than 35 degrees where you find  8" or more of fresh snow.

Problemi valanghivi

  • Storm Slabs

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

    Moderate to strong winds and moderate to heavy snowfall Tuesday night and Wednesday should promote dangerous conditions on Wednesday. You are likely to trigger a storm slab where 8" or more of snow sits above the new/old interface prior to the storm. Slabs will build more rapidly on lee slopes receiving active wind-loading, so pay attention for snow transport and deposition. Slabs will be particularly reactive if they sit on facets or surface hoar that might be buried at that interface. If weak grains are buried, they are most likely to be found in wind-sheltered terrain near treeline. We expect standard storm slabs on Wednesday and choosing terrain less than 35 degrees should give you your margin of safety. However, if you do find signs such as whumphing, collapsing, or propagating cracks as you travel, dial back your terrain selection and choose terrain less than 30 degrees that is not connected to steeper slopes above.

    Rain may fall up to 4000-4500 ft on Tuesday and if falling on fresh snow, the rain may produce shallow Wet Loose avalanches that are likely to be too shallow to be destructive. Mitigate your exposure to steep slopes if rollerballs are becoming large or your boot sinks easily into wet snow.

    (12/28/2020) Snowboarder-triggered avalanche on Shuksan Arm (NE, 5400ft). The avalanche broke 80-100ft wide and 1-2ft deep and slid on the 12/21 crust. The snowboarder who triggered the avalanche was the 5th rider on the slope and was caught and carried in the avalanche but uninjured. Photo: Colin Wiseman

Avalanche Discussion

On Tuesday, Professionals at Hurricane Ridge found 4 in of new over a very stout and slick crust on Southern aspects. Northern aspects have around 14 in of snow above the 12/21 crust. At 12 in depth there is another weak crust above the 12/21 crust. They found weak surface snow existing on Northern aspects, and SH (3-4 mm) was observed to be widespread. While skiing a SE slope the thin crust was breaking free and sliding downhill on the grains underneath. Locations where this crust also has surface hoar could set us up for a sensitive upper snowpack in Wednesday's storm. Avalanche concerns are limited to the snow above the 12/21 crust.

Monday was overcast with mild temperatures and light snow began falling in the afternoon. The sun on Monday took almost all the snow out of the trees on south aspects and put a 0.5-inch breakable crust on S aspect slopes. Steep S slopes went thru a loose wet cycle on Monday. 

See recent photos from Hurricane Ridge on Tuesday in the Media and note that avalanche conditions will be drastically different on Wednesday.

Thin snow coverage still exists along ridgelines and at lower elevations. Give yourself extra time to deal with these travel challenges. 

2020-21 Forecast Schedule: Avalanche danger ratings will be issued for the Olympics every Friday through Sunday and during mid-week holidays. During the week when the Hurricane Ridge road is closed, forecast information will be updated daily to include expected conditions and relevant travel advice under the No Rating label.   

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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