Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

You can trigger a large, destructive avalanche, breaking several feet deep, in above treeline terrain. There's a lot of uncertainty in regards to how long we'll be able to trigger avalanches on this layer, but given the recent large avalanches, avoid large, steep, unsupported slopes in upper elevation areas. A few inches of snow will fall during the day, which might form small, shallow slabs, and could run as small wet avalanches at lower elevations. 

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    Large avalanches were triggered on the Shuksan Arm with control work on Wednesday. Large natural avalanches, probably failing on the same layer, were seen by NWAC Forecaster Lee Lazarra near the Coleman Pinnacle Wednesday. They looked very recent, maybe from that morning, and it is suspected that one may have been triggered by wet loose avalanches running from the rock bands above. The avalanches are occurring just above a crust, and a weak layer of facets could exist where they are failing. With the recent avalanches we're seeing, we've got enough information to tell us that you could trigger a very large and unsurvivable avalanche in the backcountry on Thursday. 

    These avalanches are occurring on large, steep, unsupported slopes in above treeline areas. Until we know more about this weak layer, consider avoiding these slopes where they are greater than 35 degrees.  An unsupported slope refers to a slope that rolls over into steeper terrain, lacking an abrupt transition to lower angle terrain beneath that steep rollover. Pay attention to the usual signs of unstable snow such as cracking and whumphing, but these indicators are probably not signs that you will find before triggering one of these deeper avalanches. A few inches of snow will fall during the day, and increasing wind may lead to small fresh slabs of snow. You might be able to trigger small pockets in this new layer. 

    (3/16/2022)

    Two natural slab avalanches on Lasiocarpa Ridge near Coleman Pinnacle. Suspected of naturally triggering with rapid warming Wednesday morning. Wet loose in the surrounding terrain may have triggered the lower avalanche. East aspect at ~6000'.

    Photo: Lee Lazzara

  • Loose Wet

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

    "Pow is dead" is what one backcountry user said on Wednesday, after cloud cover trapped heat and humidity in, also called "greenhousing",  and snow surfaces moistened on all aspects. Wet loose avalanches were probably more of a problem Wednesday, but you might see some running at lower elevations in the new snow that falls during the day, as the older snow has already been affected by warm temperatures. If you encounter moist snow and rollerballs or small loose avalanches, consider avoiding similar steep slopes. 

    (3/16/2022)

    Small wet loose avalanches occurred on all aspects and elevations on Wednesday, including up to at least 5500ft on the north These ones ran from the usual steep, rocky starts, at Church Lake in the Canyon Creek area.

    Photo: Hilary Groh

Avalanche Discussion

Due to snow surfaces getting wet in most areas on Wednesday, you'll find a breakable crust Thursday, which will get covered by a few inches of snow during the day. It might soften at lower elevations. We've had 3-4+ feet of new snow since the 10th at upper elevations in the Baker backcountry. An observer in the Canyon Creek area reported 2-3 feet of new right side up snow, and snowmobiles triggering shallow storm slabs in it on steep rollovers Wednesday. There is enough uncertainty with our large storm slab avalanche problem that no matter where you travel, stay conservative in above treeline areas so that you can avoid triggering a large avalanche that could kill you. 

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