Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

New snow is slowly adding up, and winds are picking up. You could trigger small soft slabs, especially on steep and wind-exposed mid and upper-elevation slopes. It's time to take a step back in terrain choices and identify more avalanche-prone areas to steer around. 

Problemi valanghivi

  • Storm Slabs

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

    As new snow and winds form slabs, they may become surprisngly reactive on Friday. Slabs will likely run on or just above the most recent crust, and could be 6-14" deep. Winds are on the increase, and are expected to drift snow readily in exposed areas. Look for cracking, and use test slopes to evaluate how the snow reacts. You can also use things like skin track tests or hand shears to check and see how new snow is behaving. It'll be a day to take a step back and consider steering around the larger, steeper features with undesirable consequences if it were to slide. 

    Weak snow and crusts from the Solstice also warrant consideration on Friday and through the weekend. Any shallow slab could step down to this slightly deeper layer and become a larger and more destructive avalanche. 

    Lower elevations may warm up once again, so expect to see rollerballs and potential for very small wet slides by mid day. Steeper slopes with dry snow may also be prone to sluffing as new snow slowly adds up. These shouldn't pose too much threat unless you get caught or hit by one in the wrong place. 

    (12/1/2023)

    A rider triggers cracks just before an avalanche released in the new snow. The avalanche was 10" deep and ran 60-70ft down-slope, D1 . NE, 5,600ft, Cowboy Mtn (uncontrolled terrain)

    Photo: Pat Riffie

Avalanche Discussion

Observers reported 2-3" of newer snow in the zone, totaling 6-10" over the crust from 12/30. Another 3-6" of snow may fall overnight and through the day Friday, with moderate westerly winds at ridgetops. With a stronger storm approaching by evening, avalanche danger should start to increase into the evening hours. 

Observers reported the new snow sluffed easily on the crust at higher elevations of Rock Mountain on Thursday. They also reported triggering small wet slides on very steep, lower elevation slopes upon their descent. On Wednesday, we traveled to the north side of Lichtenberg and found about 5" of snow on a thin crust from 12/30. A thin layer of small facets and small surface hoar was found about an inch above the crust on shaded slopes at mid and upper elevations. On a south aspect at 5,800ft, the new snow wasn't bonding well to the slick crust. We initiated a small loose dry avalanche on a steeper north facing pitch right off the ridgeline at 5,800ft. Tilt tests also showed that the newer snow was not bonded very well to the upper crust.

Compression tests and extended column tests produced sudden and propagating results 16" down on a layer of larger surface hoar and facets on a slick, translucent crust from the Solstice. This reinforces what observers have been reporting over the past couple of weeks: Most slopes hold a number of sub-surface crusts in the top 16". Weak, faceted snow and surface hoar exist in between or above these crusts. This structure is fairly widespread around the region, and is likely to play a role in our instability as more snow adds up. 

Check out the observations from Nimbus Mountain on Sunday, and Skyline on Monday. Travel conditions and coverage are still thin, but improving by the day. Continue to beware of hitting exposed rocks, stumps, and creek openings, especially at lower elevations. You can contribute to the forecast! Let us know what you found by submitting an observation HERE. 

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