Bollettino valanghe

West Slopes South

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

Expect dangerous avalanche conditions as a storm brings new snow and also some rain to lower elevations. Limit travel in avalanche terrain. Stay out from under big slopes if you see widespread signs of instability like shooting cracks or natural avalanches. Greater snowfall and avalanche danger are likely on the volcanoes.

Problemi valanghivi

  • Storm Slabs

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

    Precipitation and new snow amounts will vary across the zone. It will still be enough to justify taking a step back when it comes to terrain choice. The approaching storm is warmer than anything we have seen in quite a while. While we have gotten used to cold dry powder falling on settled snow, be ready for dense slabs and upside-down snow conditions Monday.

    Fresh slabs don't take special tools to observe.  Look for shooting cracks and new natural and human triggered avalanches. Use small test slopes to gauge reactivity. Hand pits might show a stronger layer sliding easily over a weaker layer below.

    You are more likely to trigger an avalanche in downwind terrain where the wind drops new snow into thicker and more sensitive slabs.

     

    (12/30/2022)

    Example of a naturally triggered slab avalanche in wind sheltered terrain.

    Photo: NWAC public obs

  • Loose Wet

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

    Some level of wet avalanche activity is likely with snow levels rising overnight and putting some rain on the cold and dry snow we have enjoyed for the last month. Rain and thick wet snow are hard to ignore so this problem shouldn't take you by surprise. Pay attention to slopes overhead and look for signs of instability like pinwheels, rollerballs, or snow shedding from trees and rocks. Don’t linger directly under steep slopes if you start seeing any of the above.

     

    In addition to wet loose avalanches, cornices will start to sag with warmer temperatures. They will eventually get primed up to come crashing down and lay waste to anything in their path. They can also trigger large slab avalanches where a single person or even a group of people would not. This is not a widespread problem but it's still worth keeping track of what is above you be it a large cornice or steep slopes producing signs of wet avalanche instability. It's up to you to stay out of the way.

     

    (1/14/2023)

    A large (D2) wet avalanche that occurred early this season.

    Photo: Dallas Glass

Avalanche Discussion

Observations Sunday included a report of a single human triggered wind slab (photo) and easy to identify, wind loaded slopes on Bullion Peak. An NWAC Forecaster on Gold Hill, just over the frontier in East South, reported about 6" of dense new snow by day's end and stubborn wind slabs but sensitive cornices. No other signs of instability were observed and solar aspects were capped with crust to 4800'.

At Crystal strong winds from the southeast stayed steady through the day with gusts into the 50's. A few inches of new snow was on the ground by the end of the day. Winds were in the moderate range at Paradise and White Pass. Overall the level of reported avalanche activity was less than expected and conditions didn't match the forecast danger for Sunday.

Backcountry travelers around the zone found roughly 2 inches of new snow being drifted into fresh slabs Saturday. NWAC Forecasters and avalanche professionals in the Crystal Mountain backcountry reported triggering shallow wind slabs on steep slopes in addition to older, stiffer slabs left over from Thursday’s major wind event. Shooting cracks were produced with uptrack tests and reverse loading/double cornice lines were observed due to the wind direction switch.

 

Regioni coperte