Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

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

Easterly winds will resume and you can still trigger dangerous avalanches in wind drifted snow. Many people throughout the Cascades have been getting surprised by triggering avalanches in unusual locations, and drifts may also break into older weak snow layers up to a foot or more deep. Avoid steep slopes where you can identify wind-loaded surfaces. 

Problemi valanghivi

  • Wind Slabs

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

    Those pesky easterly winds will pick up a little again on Monday. We might get a dusting of new snow, which isn't enough to impact the avalanche forecast. Most of the snow available for transport has probably already been redistributed, since we've already had plenty of these wind events in the last week. Remain alert for lingering or newly building slabs by watching for snow transport along ridgelines and identifying firmer, or textured snow beneath your feet.

    Beneath the wind-affected snow, weak layers may be present, having formed in the last 2 weeks. Surface hoar and other weak, faceted layers may mean you could get an avalanche failing beneath the newly formed wind slab,  possibly as deep as the Early February Crust, around a foot and a half deep. This setup can prolong instabilities and make for surprising avalanches, that could break in unsuspecting places and further than you expect.

    Search for textured snow surfaces and stiffer-feeling snow. Long, shooting cracks or whumphs are strong indicators that weak snow is present. You're most likely to find drifts below ridgelines, in gullies, on steep rollovers, and around rocky outcroppings. Use small test slopes to see if you can trigger small avalanches, although these might not always be accurate slope tests. New wind slabs could break a few inches, six inches or a foot deep, but there is that small chance that an avalanche could break deeper. Given the wide variety of concerns, avoid wind-loaded slopes on terrain over 35°.

    (2/14/2024)

    Drifting snow from easterly winds were easy to observe from afar. Chiwaukum Range from Stevens Pass. If you notice active wind drifting or signs of old transport, avoid traveling on the affected steep slopes. 

    Photo: Matt Primomo

Avalanche Discussion

An OBSERVATION from the Lake Valhalla area on Sunday reported finding a "buffet of crusts", all of which were unpleasant for traveling on. In general, snow is probably not available for transport where this person traveled. There likely aren't reactive wind slabs in many of these locations, as observed by the party. We do suspect that especially at upper elevations, newly transported wind drifts could react to a human trigger.

On Tuesday, a skier triggered an avalanche 1 1/2 ft deep on the early February Crust on a NE aspect at 6,500ft on Jim Hill (observation). A different party on Jim Hill reported large, whumphing collapses that same day. Other observations from this zone and neighboring zones show the layer has been problematic. Currently, we don't have enough information to list a persistent slab problem, but by avoiding steep, wind loaded terrain you're most likely avoiding this problem too. 

Other observers reported finding wind-sheltered areas where a right-side-up snowpack with light, dry snow exists on north-facing aspects. Your main concern in these locations is small, dry loose avalanches on steep slopes. At lower elevations, you'll find variable crusty snow surfaces and plenty of bare patches and holes in the snow. Travel carefully to avoid an unexpected encounter with unfavorable surfaces.   If you get out, please help us by submitting an observation.

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