Bollettino valanghe

West Slopes South

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Stormy and complex weather will create dangerous conditions in the mountains on Saturday. Look for heavy snow over weak snow, blowing wind, or unconsolidated wet snow as indicators to stay off slopes 35 degrees and steeper. With a variety of weather outcomes, you will need to constantly re-evaluate your plan and choose appropriate terrain. 

Problemi valanghivi

  • Storm Slabs

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

    Heavy snowfall rates, warming temperatures, and strong to extreme winds will all aid in the development of Storm Slabs on Saturday throughout the West South. Slabs will be thicker above the rain/snow line, in wind-prone areas, or on the volcanoes where more snow is expected. We are expecting an upside-down snowpack to develop in many areas of the zone by day’s end, which is a recipe for slab avalanches. Use small test slopes and hand pits as you travel to determine the depth and reactivity of the new storm snow. If you find heavy snow overlaying light snow or notice signs of wind-effect such as textured surfaces, blowing snow, or freshly formed cornices, stay off slopes over 35 degrees.

    (12/11/2021)

    During a stormy Saturday last weekend, this avalanche in the Crystal Mountain area caught a party of 6 tourers and unfortunately resulted in a fatality.

  • Loose Wet

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

    The timing and elevations for wet avalanches are hard to predict for Saturday, but your easiest indicator will be the type of precipitation falling from the sky. If you encounter rain falling on cold dry snow, you should anticipate wet avalanche activity. These avalanches often start at a point and are capable of entraining snow, triggering slabs, and traveling far distances as they descend. Rollerballs, pinwheels, and fan-shaped avalanche debris are visual clues you can use to help identify these avalanches. If you notice signs of wet avalanches or find unconsolidated wet snow, stay off of terrain features greater than 35 degrees and avoid traveling underneath steep rocky slopes and cliff bands where snow could shed from above.

    (1/1/2021) Example: Wet avalanches can entrain lots of snow as they descend and become more problematic when terrain traps are involved.

    Photo: Dan Jones

Avalanche Discussion

The West South could see rain, freezing rain, snow, and strong to extreme winds throughout the forecast period, leading to a lot of uncertainty about how the day will unfold. What we can feel confident about is that freezing levels will rise throughout the day, making Saturday a dangerous day to be in the mountains. It was only a week ago that an unfortunate fatality occurred within our zone during a storm day. Be sure to make observations as you travel and do your due diligence before stepping into avalanche terrain. Whether precipitation is falling as rain or higher density snow, avalanche problems should develop no matter what your location or elevation. 

At upper elevations look for slabs overlaying the lower-density snow that currently exists through the zone. Slab development will be aided by periods of high precipitation rates and on leeward slopes by the increasing winds. We have been watching the 12/8 crust recently as a potential weak layer in some areas of the zone. Although most avalanches should occur at the new/old snow interface, don’t forget about this deeper layer and the potential for avalanches to step down in some locations. 

At lower elevations, the snowpack is still in the early stages of development for the season. We have talked recently about open creeks, shallowly buried objects, and other natural hazards that pose a risk to your travel. These hazards may be more prominent with the return of rain and need to stay on your radar. 

Regioni coperte