Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger will likely start out on Low, but as a few inches of snow arrives with wind, likelihood of triggering small avalanches in newly drifted snow will increase.  Search for actively blowing snow, identify wind-textured surfaces, feel for stiffer snow beneath you, and avoid steep slopes where you find these deposits. Crusts exist beneath the new snow on many slopes, and both wind-stiffened deposits and loose, dry snow will probably slide easily on the crust. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Danger will likely start at Low, but a convective spring storm is expected to bring about 3 or 4 inches of snow by the end of the day, along with increasing afternoon winds. In exposed areas, wind will build slabs that could reach 6 inches to a foot or more. Avalanches should remain small, but even small slides can have serious consequences in high-consequence or extreme terrain.

    A crust has formed on all aspects except due north after several days of warm, sunny weather. Any new slabs sitting on this slick surface may slide more easily than expected. Small new drifts of snow will likely deposit around features, on steep rolls, and in gullies. They may have a textured surface, or alternatively, a smooth, pillowed look to them. 

    Look for clear warning signs like shooting cracks. Use your hand to test how easily new slabs break on the layer below. Avoid steep slopes with fresh wind slabs, especially if you are above cliffs, trees, rocks, or gullies.

    Example photo: This small test slope, showing obviously wind-textured snow, worked great for checking reactivity of small wind slabs.  

    Photo: Julz Holder - Grounding Truth

Avalanche Discussion

Observers at both Heather Meadows and Cascade Pass saw afternoon snow showers on Saturday, resulting in a small amount of new snow. An observer went to 6000ft from the Heather Meadows area on Saturday and reported no wind slab development, but loose, dry sluffs in the new snow were sliding far and easily on the underlying crust. At Cascade Pass, snow was highly wind-affected, with a thinner layer over the stout March 25 crust, which sits 6-10+ inches deep at Heather Meadows, but was closer to 2-4 inches here, with highly variable scoured and drifted spots up to 8 inches (observation).

On Saturday morning we saw our last bit of sun and moistening of steep slopes facing the sun. A few small natural wet loose avalanches ran down, despite a far warmer day on Friday. Slopes on east, south, and west aspects will remain hard and crusty on Sunday before adding a bit of new snow on top. North-facing areas may still have soft dry snow with varying amounts of wind-affect. Despite the lack of underlying crust, new wind slabs might still slide easily over the old snow. 

Temperatures will remain cooler for the next few days, so dry snow should remain soft, and we don't expect any melting or retreating snowlines. Remember that our unseasonably thin snowpack still has many hazards even through mid-elevations, with open creeks and holes in abundance. 

Regioni coperte