Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

The threat of destructive, wet avalanches will continue to make for dangerous conditions on Thursday despite the end of heavy rainfall. Limit your exposure to steep or rocky terrain overhead. 

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–3

    After a full two days of rain, wet slabs, glide avalanches, loose wet avalanches, and falling cornices are all hazards for those willing to travel in slow and challenging conditions. Rainfall will begin to taper Wednesday night and will lower the likelihood of encountering an avalanche. On the other hand, wet slab and glide avalanches can happen long after heavy precipitation ends as water continues to percolate through and weaken the snowpack.

    The danger comes from the unpredictability and destructive potential of these avalanches versus the chance of actually triggering or being buried by one that releases in terrain above you. 

    Strongly weigh the risk of traveling on or below avalanche terrain on Thursday. These are not avalanche problems that can be “managed” - all you can do is stay out from under steep terrain that can produce these avalanches. Watch out for and avoid traveling under sagging cornices, glide cracks that indicate where the entire snowpack is slipping on the ground below, and large, unsupported blocks of snow that linger around an area that has already slid. Areas of recent wet avalanche activity are where you are likely to see more of the same until the snowpack has time to drain and temperatures cool significantly.

    (1/11/2022) A wet slab avalanche near Excelsior Peak. This probably occurred Tuesday morning. Around 5100 ft, S facing.  : NWAC Public Obs

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    In the West North we are still suspicious of a layer of surface hoar buried on December 21st. It produced a handful of very large avalanches centered around Shuksan Arm in late December. Some released naturally while others were triggered with avalanche mitigation work. The added weight of rain on the snowpack plus warmer temperatures make for a good test to determine whether any more large, alpine slopes could release on this layer. Chances that one of these very large avalanches could occur are unlikely, but keep it in the back of your mind as more weight is added to the snowpack if you're out on Thursday. Be aware that large deep slab avalanches from higher terrain could run into lower elevations where avalanches are not normally seen.

     

     

Avalanche Discussion

Heather Meadows received nearly 5.5” of precipitation from January 10th to midday on the 12th. It fell nearly all as rain except for at the highest elevations.  The rain fell on a cold, dry snowpack near and above treeline and triggered a natural avalanche cycle consisting of loose wet, wet slab and glide avalanches. Below treeline areas saw significant rain earlier in January and less avalanche activity we reported from this elevation band in the West North. Despite no new observations on Wednesday, one can suspect from rainfall totals that continued heavy rain maintained or even accelerated the pace of natural avalanche activity.  High freezing levels into the weekend could sustain melting and add more water to a snowpack already saturated with rain.

If you make it to the alpine you may encounter unstable storm and wind slabs of dry snow in the highest terrain.

 

 

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