Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

After a cold clear night, another storm will move into the southern Cascades Wednesday afternoon. You can still trigger avalanches where winds have blown snow into deep drifts over the last few days. Winds have repeatedly shifted directions, and you may find unstable snowdrifts on all aspects near ridgelines. Steer around steeper terrain with pillow-like drifts of snow.

Problemi valanghivi

  • Wind Slabs

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

    After a clear night, the unsettled, stormy weather will return to the Cascades. Expect increasing clouds in the early afternoon with strong gusty winds and light snowfall. Even after the warm sunny day on Tuesday, plenty of snow is available for transport, and winds will build fresh shallow slabs near ridgelines. These fresh slabs may form over crusts on southern aspects and possibly weaker snow on true north aspects. The last week brought shifting and atypical wind patterns, so expect wind slabs of varying ages on opposing aspects and in potentially unusual locations. Visual clues such as textured surfaces, cornices, and pillow-like drifts of snow can help you identify and avoid fresh wind slabs, while you may need to use a probe or pole to feel for stiffer layers in the upper snowpack to identify older, more stubborn wind slabs. Avoid steep terrain near ridges in alpine terrain, and consider sticking to wind-sheltered or lower angle slopes at lower elevations. With minimal direct observations and uncertainty about the distribution and sensitivity of these overlapping wind slabs, it is important to enter new alpine terrain slowly and make observations before committing to steep terrain in wind-affected areas. If you see signs of instability such as shooting cracks or feel the snowpack collapse beneath you, move to lower angle or wind-sheltered terrain.

    (4/11/2022) Wind slabs were found in some unusual spots. Fresh slabs were observed on slopes often stripped by the wind. Photo: Dallas Glass

Avalanche Discussion

On Tuesday, areas near the Cascade crest picked up around 10 inches of fresh snow, with accumulations tapering further east in the zone. Wednesday will likely start with clear skies in the morning, but clouds will move into the region by the afternoon, followed by strong, gusty winds and light precipitation. The Cascades have been in a tricky weather regime for over a week, with shifting winds, atypical storm patterns, and sun breaks when we expected clouds. The Mission Ridge area and Wenatchee Mountains have been particularly unpredictable in exceeding forecasted precipitation totals. This weather has increased uncertainty in both the weather forecasts and the avalanche forecasts. It is not unusual for spring weather to be challenging to forecast, and you should plan for some of this uncertainty when you head out into the mountains. Keep your senses tuned into the snow and look for signs of deteriorating snow stability such as recent avalanches, wet snow surfaces, actively blowing snow, and heavy snowfall.

If clouds are slow to accumulate in the zone, wet loose avalanches may be possible on sunny slopes. With the strength of the spring sun, even short sun breaks can quickly make the recent snow wet and heavy. So if you find yourself on slopes in direct sun with snow surfaces becoming moist or rollerballs forming, it will be best to move to lower angle or shady terrain. Even a small wet loose avalanche could be consequential if it knocks you off your feet and carries you into trees, rocks, over cliffs, or buries you in confined terrain. 

Snow surfaces melted from recent rain, warm temperatures, and sun on Monday and Tuesday. Cold temperatures overnight on Tuesday will refreeze these surfaces, creating challenging travel conditions at lower elevations on thick, icy, and breakable crusts. The more recent melt-freeze crust from 4/18 may have 8-10 inches of snow over it in areas near the crest, and an observer in the Teanaway area on Tuesday found 1-5 inches of storm snow from Monday and Tuesday. Areas near Icicle Creek may have picked up 6-10 inches of snow from that same storm. On Sunday, an observer from the Teanaway area found 1-2 feet of snow over the 4/8 crust near Jolly Mountain. We lack direct information from many locations in the East Central zone, but it may be worth digging down to investigate these interfaces before committing to steep or consequential terrain. Please help us finish the season strong and submit an observation to the platform if you make it out. 

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