Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

You can expect to see about 6 inches of snow by the end of the day, and new snow avalanche concerns are back. We're not expecting large amounts of avalanche activity with the storm snow, but on steep slopes at higher elevations small dry slab or loose snow slides may run, while at lower elevations, moist snow could slide. Although failures are unlikely, continue to avoid terrain beneath glide cracks and large, saggy cornices. 

Problemi valanghivi

  • Storm Slabs

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

    Incoming new snow will fall with very little wind and temperatures will cool. It may be more appropriate to call this problem a "new snow problem" than a storm slab, but that's not on the drop-down menu. In general, we don't expect there to be too much avalanche activity, and what there is will be relatively small.  This doesn't mean you should blindly make your way into all steep terrain on Saturday.

    Slab development will probably be limited, given the previously described snowfall conditions, but it's not completely out of the question that small slabs could form, especially at upper elevations. Avalanches may behave more like sluffs, or dry loose avalanches. In terrain 35° and especially when it's even steeper, the snow could slide on its own, or maybe once you make your way onto the slope. We're unsure how well the snow will bond to the underlying layer. Beneath it, there may be a crust, or in some spots, especially at lower elevations underlying snow could be moist and soft, and avalanches may entrain some of that snow. In general, at the snow/rain interface in the mid and lower elevation band, small wet loose avalanche activity could occur. If you see much natural activity avoid traveling on nearby steep slopes and beneath them.

    Use extra caution when you're in high-consequence terrain, like in areas where there are cliffs beneath you, rocks, trees, or gullies that could pile shallow slides into deep deposits. These are areas to be particularly concerned about on Saturday, as they seriously magnify the consequence of even a small slide if you are caught. 

    Example photo: Thin, slabs like this one, or dry wet or loose avalanches may run in the new snow on Saturday. 

Avalanche Discussion

The last report of a springlike deep wet variety of avalanche was in the Baker backcountry on Monday, when a large cornice failure on a north-facing slope at 5000ft produced a large avalanche on the slope beneath. Despite the lack of a good solid refreeze, we're removing deeper wet snow avalanche problems from the list  but are continuing to bring the topic up in this section. Temperatures will thankfully cool a bit more over the weekend, but we still recommend avoiding travel beneath gaping glide cracks or large, saggy cornices. If you must travel beneath them, do so quickly. 

Wet and springlike avalanche activity has been our main focus for more than a week. Varieties of wet avalanches were reported from all over the zone. That being said, despite the 10,000+ ft freezing levels after several feet of cold, dry snow in the previous weeks, we were surprised not to see as much widespread wet avalanche activity as we suspected would happen. The peak activity appeared to happen last Friday, 3/15, the first true day of warming, where predominantly wet loose and some wet slab activity occurred. One observer reported hearing almost nonstop noises of avalanches crashing down from their location at Schreibers Meadows on that day. 

Snow cover rapidly receded since the start of the warm weather on 3/12. The snow base at Heather Meadows dropped almost 3 feet since then. Snowlines start at or well above 3000ft depending on aspect. Travel hazards have plagued us this year, and still remain more of a concern than if we had a usual deep snowpack. Unexpected openings near creeks and rock features are important to be aware of during your outing, which you may not find until you've fallen into them. Snow conditions will be variable, and there's a good chance you'll find a crust, beneath the new snow. At lower elevations, the snow will probably be punchy.

Your avalanche, snowpack, or weather observations are extremely valuable to the avalanche community. Help create a more accurate avalanche forecast by submitting your observations HERE. 

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