Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Stick to simpler, smaller, and lower-angled terrain while the snowpack adjusts to 3-5’ of recent new snow and heavy wind-loading. Deep snow immersion is a real hazard. Travel with a partner and keep them in sight at all times.

Problemi valanghivi

  • Storm Slabs

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

    You can run across three varieties of new snow avalanches on Friday. 

    More snowfall, lots of light, dry snow on the ground, and periods of stronger wind will create another round of slabs.  While more likely in wind-loaded terrain, be ready to trigger one on any steep slope. You can identify and asses these by tracking areas of stiffer or deeper snow, slope cuts and hand shears.  Where there isn’t much of a slab at the surface, expect to trigger dry loose avalanches if you start pushing snow around in steep terrain. 

    The final issue is simply how much new snow is out there. Given the amount - 4’ or more in some areas - it seems safe to assume that any slope holding persistent or other weak layers slid during the storm. On the other hand we don’t really know what happened out there until we can see. Did most slopes release naturally? Or are there a bunch that need just a bit more snow and wind loading to tip the scale? Maybe you could even trigger a deep one where the snowpack is shallower? Hard sayin’ not knowin’ or something like that. The mountains need time to adjust to all the new snow. 

    (2/29/2024)

    Natural slab avalanche on the east aspect of Herman at 4600'. Visible on the shallow ridge in the middle of the photo, just left of center.

    (HS-N-D2-U)

    Photo: Julz Holder - Grounding Truth

Avalanche Discussion

Look for sun breaks and periods of warming between snow showers over the next few days. The March sun is strong and can quickly warm up the snow surface despite cold temperatures. If the sun is out, lookout for rollerballs and small loose snow avalanches. Warming can also form a reactive slab from loose dry snow at the surface.

If you haven’t been in the mountains in the last week be ready for a totally different landscape. The snowpack in many areas effectively doubled since Feb 24th - Heather Meadows saw the height of snow increase 218% from 53” on the 24th to 116” on the 29th.  Deep new snow made for some challenging travel for both human-powered and motorized backcountry users. While low elevations are finally building a snowpack, expect it to be unconsolidated with plenty of low snowpack hazards mixed in with the pow.

Observations are limited due to poor visibility, travel conditions, and avalanche danger in the past few days. Avalanche control work at Mount Baker Ski Area produced numerous slab avalanches to D2 and larger. Backcountry travelers triggered dry loose avalanches that pulled out the top 8” of light-density new snow. Also, a large natural avalanche with a 3-5’ deep crown was observed on a wind-loaded slope in the Baker, BC. Better visibility on Friday will probably show a much wider pattern of avalanche activity.

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