Boletín de aludes

Stevens Pass

Northwest Avalanche Center
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Peligro de aludes

Thu
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Continue to use caution on the heels of a widespread avalanche cycle. You may still be able to trigger avalanches on Wednesday and some of them could be very large.   Dangerous conditions include a chance for avalanches (wet and dry) to break on deep layers buried in February.  

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–2.5

    Dangerous conditions may remain above treeline. Avoid slopes 35 degrees and steeper, especially on leeward sides of ridges. Minimize the time that you're under large avalanche paths and runouts. Freshly built slabs could approach 5-6ft deep at upper elevations and could break at a number of storm interfaces.

    Widespread large to very large avalanches occurred on Monday in the storm snow. While natural activity has tapered off, there's uncertainty about how easily you could trigger these very large avalanches. Manage the risk by minimizing your exposure to avalanche terrain. 

    (3/1/2022)

    A slab avalanche in the Stormie's area near Skyline lake. E, 4,600ft

    Photo: Matt Primomo

  • Wet Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Wet slabs can be surprising and offer little warning before breaking widely across a slope. Use caution on slopes 35 degrees and steeper where meltwater has reached layers and crusts in the upper snowpack. You may also be able to trigger loose wet avalanches on steeper slopes. Rollerballs and other, recent wet slides are indicators that you could trigger more wet avalanches. Wet avalanches could break on recent storm layers or even older layers. A weak layer of facets and surface hoar buried on the 26th as well as a series of underlying crust/weak layers could produce these surprising avalanches.

    (3/1/2022)

    A very large (D2.5) natural avalanche occurred at Stevens Pass Resort while the mountain was closed on the 28th or that night. This ran from Cowboy Ridge onto a groomed run below.  SPMR patrol reported similar natural avalanches widespread throughout much of their terrain.

    Photo: John Meriwether

Avalanche Discussion

Heavy snow, rain, and poor visibility have limited access and information over the past two days. Skies cleared enough on Tuesday to see a number of larger avalanches including- the Wellington Path on Windy Mtn (D3), Lichtenberg Mtn, SE (D3.5), the Swath on the north end of the Chiwaukum range (D2.5), and a sizable D2 in the Stormie's area near Skyline Lake. WSDOT forecasters and Stevens Pass Patrol reported a widespread natural cycle of large to very large avalanches (up to D2.5) on Monday. They reported both slab and wet loose avalanches. Also on Monday, WSDOT avalanche workers triggered a very large (D3) avalanche with explosives in the Old Faithful path. Since Feb 26th the Schmidt Haus weather station at Stevens Pass recorded almost 8" of water equivalent. The first 3" of water brought 28" of snow accumulation into the morning of the 28th. The rest of the precipitation has mostly fallen as rain at 4,000ft but more snow may have accumulated above 6,000ft. 

The Feb 26th interface lies beneath the recent storm snow. On many slopes, near-surface facets and surface hoar likely stayed intact and got buried. Beneath this, there are a number of crusts and potential weaker layers buried in February. The Valentines Crust serves as a prominent marker, as it's fairly thick in most places. Observers noted very reactive conditions on Sunday, with storm slabs breaking on the Feb 26ht interface. Observers reported numerous triggered slab avalanches including a close call with a rider buried to their neck on a NW aspect near Skyline. Some avalanches on south-facing slopes even triggered other slides nearby (sympathetic).

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