Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Dangerous conditions remain after over 4 feet of snow and strong wind in the past 5 days.  Avoid traveling through or under large avalanche paths and upper elevation slopes steeper than 35 degrees. Give the snowpack another day to adjust to the new load.

Problemi valanghivi

  • Storm Slabs

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

    The most dangerous slopes will be near and above treeline where both new snow and westerly wind built thick slabs. You could trigger large avalanches in steep wind-loaded terrain at upper elevations. Watch for cracking in the snow and stiffer, wind-sculpted features. These avalanches could run into lower elevations. Seek out lower-angled, wind-sheltered terrain away from overhead hazards while the the new snow time settles and stabilizes.

    At lower elevations, use caution on slopes 35 degrees and steeper. You could trigger storm slab avalanches and loose sluffs that may run far and could be big enough to bury you. Steer around convex rollovers and unsupported slopes. You may find a few storm interfaces that could be problem weak layers including stiffer, recent snow resting over softer snow as well as a weaker layer of snow about 2 feet below the surface. Use snowpack tests and small slopes to assess how easily the new snow slides.  

    (2/13/2021) A small skier triggered storm slab (D1) on a north aspect at 5400ft in Lanham Creek that failed on weak snow at the February 11 interface.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    A heavy load from recent snow and wind has maintained the threat of very large deep persistent slabs. It's been just over a week since the last known avalanche on the mid-January weak layer. The new load and a lack of observations will keep us traveling with these avalanches in mind. Continue to stay well away from big, steep, and open slopes near and above treeline. Put a large buffer of terrain between where you travel and large avalanche paths, especially leeward wind-loaded areas. About 5-6 feet below the surface, you can find a layer of grainy, faceted snow above or around a crust that formed in mid-January. Sudden and propagating snowpack tests on this layer can indicate the potential for an avalanche. 

    (2/7/2021) A two party involvement occurred on February 7th. Skiers triggered a very large (D3) avalanche which partially buried 2 people. The avalanche released on a NE aspect at 6,100ft on Jim Hill in the Stevens Pass zone.

Avalanche Discussion

As of Tuesday evening at least 19" of snow accumulated with just under 1" of water equivalent during the day. Over 4 feet of snow has fallen with 3" of water at Stevens Pass since the 12th. Strong westerly winds began on the 15th and will continue into Wednesday.

On Tuesday, an observer reported "oppressive backcountry travel" and deep snow immersion hazard. Trail breaking was knee to shoulder deep with skis on. Dangerous tree well and deep snow immersion hazards exist. Avalanche professionals confirmed a widespread cycle of natural avalanches around midday. WSDOT avalanche workers triggered multiple large and a couple of very large avalanches during control work early Tuesday AM. On Monday, an observer reported many natural avalanches on steep southerly aspects below Skyline Lake. In the neighboring East Central zone, observers remotely triggered a very large avalanche on south aspect at 6,200ft. On Saturday, a large natural avalanche in the Old Faithful slide path even hit Highway 2 near Stevens Pass after heavy snow and strong easterly winds.

Unfortunately, a snow biker triggered an avalanche on the deep persistent layer in the East Central zone on February 8 and was buried and killed. For more details and information, see the Accident Reports page and the post-incident investigation video below. 

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