Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

Human triggered avalanches are still possible at moderate avalanche danger. You're most likely to trigger an avalanche in wind-drifted snow at mid and upper elevations. Search for firmer feeling slabs beneath you, or wind affected surfaces and avoid traveling on steep slopes where you identify these characteristics.

Problemi valanghivi

  • Wind Slabs

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

    On Sunday there was a suspected human-triggered avalanche in an upper elevation chute in the Baker backcountry (observation). The avalanche occurred in a wind-loaded gully, which is the kind of place where you might just be lucky enough to find and trigger an avalanche on a wind slab. When danger isn't high, there probably aren't obvious clues like natural avalanches or slopes that are very touchy, yet if you find the right spot you can still trigger an avalanche that could bury and kill you. 

    Wind slabs usually form around rocky features and outcroppings, in gullies, on steep rollovers or beneath cornices. You can identify them by feeling for stiffer snow beneath you or visualizing smooth, pillowlike features or textured snow surfaces. You may see obvious clues like long, shooting cracks. Identify locations where wind slabs tend to form, and search for characteristics of wind slabs like the ones that were just listed. If identified, steer around steep slopes. When in doubt, avoid slopes greater than 35°. 

    (12/29/2024)

    An unwitnessed slab avalanche triggered in the gully. The crown was 2' deep in places. It was possibly human triggered from the previous party on the slope. 5800ft, E. SS-AS-D1.5-U 

    Photo: Jess Trimble

Avalanche Discussion

Forecasts are calling for only a couple inches Sunday night, and another inch during the day. Low density snow may cover older wind slabs, making them harder to identify. We've had unrelenting weather lately, where most days we've seen several inches or feet of snow. We received about a foot of snow Friday night and first thing Saturday morning there were reports that widespread shallow avalanches were being triggered in the new storm slab. Relatively warm temperatures settled the new snow layer out quickly, and by midday the snow was less reactive and moist to about 5000ft. We expect most avalanche activity to now be limited to wind loaded features.  

On Monday you might see sun breaks but temperatures will be a little cooler than previous days, with freezing levels around or just above 2000ft. Previously wet surfaces, up to almost 5000ft, could now have varying amounts of crust. We don't anticipate any wet avalanche activity. If there is more sun than expected, there may be more activity. 

With more pleasant conditions on Monday we expect people to be venturing further and higher into the backcountry. We have limited information from upper elevations. Continued storms and bad visibility have minimized access to these areas. It's likely that over 4 feet of snow exists over the 12/21 Solstice Crust. Colder alpine temperatures, unlike temperatures above and flirting with freezing at mid and lower elevations may have limited the rapid bonding we've seen down lower. Bonding at the 12/21 crust may also be weaker at higher elevations as well. Given the uncertainty, plan on making thorough snowpack assessments before exposing yourself to steep slopes if you're making your way towards upper elevations on Monday.

At lower elevations, the snowpack has been impacted by warm temperatures and rain. The bottom of the lower elevation band has minimal snow. With a slightly lower temperature for Monday we don't expect to see avalanches at lower elevations. If you make it into the backcountry, consider SUBMITTING AN OBSERVATION, so that we can write better avalanche forecasts for you. 

 

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