Bollettino valanghe

West Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A widespread natural avalanche cycle occurred over the past 24 hours, and recent storm snow (6ft since Saturday) needs time to settle and stabilize. You can trigger very large and destructive avalanches in wind-loaded areas at upper elevations. Choose simple low-angle terrain and avoid slopes 35 degrees and steeper.

Problemi valanghivi

  • Storm Slabs

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

    Expect dangerous conditions at upper elevations after a week-long storm and avalanche cycle. Human-triggered avalanches remain likely on slopes 35 degrees and steeper. The most dangerous conditions exist in wind-loaded terrain at upper elevations where avalanches could break several feet thick and grow very large. Shallower avalanches in non-wind loaded areas may also be easy to trigger and large enough to bury, injure, or kill a person. Seek out supported terrain away from overhead hazard and avoid convex slopes and areas near and below cornices. Carefully evaluate the snowpack looking for shooting cracks, collapses, and recent avalanches. Use small slope tests and hand pits to investigate the recent snow and determine which layers are most sensitive to triggers. Be patient as the snowpack continues to adjust to the massive load of new snow. 

    (01/06/21) Very large avalanches on the north aspect of Table Mountain that ran naturally in the past 24 hours. Photo: Phil Straub

  • Loose Wet

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

    Keep a close eye on steep, rocky, sun-exposed slopes where solar radiation may be strong enough to destabilize snow surfaces and create loose avalanches. Cloud cover may limit solar radiation in the afternoon, and the best chance for strong unfiltered sunshine will likely be in the morning hours. Watch for rollerballs and pinwheels as evidence snow surfaces are becoming wet and weak. Minimize exposure to slopes greater than 35 degrees in direct sunlight and move to shaded terrain to avoid the problem. Loose snow avalanches could be dangerous on their own and even trigger large slab avalanches as they run downslope.

    (1/1/2021) Example photo of pinwheels and rollerballs

Avalanche Discussion

An impressive avalanche cycle occurred during the storm Tuesday night into Wednesday. Large natural and triggered avalanches failed 6-12in deep within the 24-hour storm snow, and very large naturals (D3) were reported in northerly, upper elevation, wind-loaded terrain with crowns several feet thick. Avalanche activity has been ongoing during this prolonged and heavy loading event, with several rounds of natural avalanche activity over the past week. Since January 1, the Heather Meadows weather station reported over 13in of water translating to over 6ft of new snow. Snow depths are well above average 4000ft and higher with 11-13ft of total snow on the ground. Below 3500ft, recent rains have caused significant melting of the shallow low-elevation snowpack. In addition to dangerous avalanche conditions, non-avalanche hazards exist including tree well and deep snow immersion. Find out more information about deep snow safety HERE.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte