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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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Assess new snow depth and bonding at upper elevations or anywhere you suspect wind-transported snow. You are more likely to trigger an avalanche on unsupported terrain features like convex rolls,  gully walls, and above or next to cliffs. Look for small wet avalanches on slopes facing the sun.

Problemi valanghivi

  • Storm Slabs

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

    The new snow from Saturday night was reported as well bonded to the rain crust. Signs of instability at mid-elevations were limited to small slabs and sluffing. It’s still worth investigating wind-loaded slopes - and all slopes at upper elevations - before diving into anything bigger or steeper.

    You can use the rain crust about 10-16” down from the surface to track changes in new snow depth. More and stiffer snow = a greater chance of triggering a slab. Use a ski pole or simply dig down with your hand to find the crust as you gain elevation and change aspects. Look for instability using test slopes, hand shears, and other simple tests.

    Choosing lower-angle terrain features, or slopes with no consequence in the runout below, are easy ways to reduce risk in avalanche terrain.

    A human triggered slab avalanche from a prior winter.

    Photo: NWAC Public Obs

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Southerly aspects could see small avalanches as they warm. Snow falling from cliffs and trees often initiates loose snow avalanches lower on the slope. Don’t linger on or directly under steep slopes where you rollerballs, recent avalanche activity, or other signs of instability. 

    Be prepared to get dry loose snow moving down the hill with you if you venture onto steep and shadier slopes.

    Small rollerballs are a sign that slopes facing the sun are warming and could produce wet avalanches.

    Photo: Andy Harrington

Avalanche Discussion

It's safe to assume the glide avalanche cycle is over, but glide avalanches and cliffs shedding blocks of snow might still be a hazard in a few areas. Limit time spent directly under cliffs holding snow, glide cracks, or slopes with wrinkled snow. The likelihood of seeing a new glide avalanche is quite low but the consequences would still be dire if you were in the wrong place at the wrong time. 

It’s entirely possible to trigger avalanches at Moderate. It’s just that you will probably only find them in terrain with certain characteristics, and if you did trigger one it would likely be small. With clear skies in the forecast, traveling into upper elevations and more distant terrain will be more reasonable. There is also no information from these areas. Prepare to assess conditions for yourself and change plans if you find avalanche danger different than forecast. You may find faceted layers and a more reactive snowpack farther east in the zone, or at the highest elevations, where less rain fell.

The snowpack in West North took a beating before gaining back lost ground with the last round of snowfall. Under the new snow, moist, consolidated snow is found for the next three to four feet at mid-elevations. Low elevations lost significant snow cover and in many areas, there just isn’t enough snow to produce avalanches.

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