Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Sunshine and warm temperatures should out muscle strong winds to soften surfaces and produce wet avalanches conditions on Tuesday. If you find the snow surface getting sticky and wet or notice snow shedding from trees and rocks, head toward shadier slopes.

Problemi valanghivi

  • Loose Wet

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

    There may be a battle between the nice springtime weather and unseasonable winds which will determine the likelihood of wet avalanches on Tuesday. As the snow surface starts to soften on sunny slopes, take the time to see if you are sinking into the snow past your ankle. If so, you need to put wet avalanches on your radar and look for other indicators that the upper snowpack is destabilizing such as rollerballs and pinwheels or snow shedding from trees and rocks. If you find yourself in an area exposed to strong east winds, it may take longer for Wet Loose avalanche conditions to develop. These slides often start at a point such as near trees or rocks, can entrain significant snow, and will fan out as they descend, possibly growing large and traveling long distances toward lower elevations. Other wet avalanches such as wet slabs, cornice collapses, or blocks of snow falling off rocks could occur when these conditions are met and are very difficult to predict. Your best mitigation technique for all wet avalanche problems will be to head toward shadier slopes and keep aware of your overhead hazard.

    (4/11/2021) Rollerballs and snow shedding from rocks and trees were found near Crystal Mountain on Sunday 4/11 and are precursors to Wet Loose avalanches. They're a great indicator that it's time to head toward shadier slopes.

  • Wind Slabs

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

    The winds alluded to above should be significant for this time of year and slopes that do not see direct sunshine could still be holding cold and dry snow. This snow could be transported into shallow Wind Slabs or there could be some lingering slabs from this past weekend. Take a look for textured snow surfaces or pillow-like piles of snow to help you identify wind-loaded features to avoid. They will be more likely as you ascend in elevation and often form near rocky features such as confined gullies or at the base of cliffs. You should also look for them on leeward slopes near ridgelines or on convex rollovers. In areas with dry snow, you can use uptrack tests or test slopes to determine the slab potential and if blocks of snow are failing easily. If you find poorly bonded snow or suspect a terrain feature to be wind-loaded, you should seek out lower-angled options. 

    (4/11/2021) Wind textured surfaces, cornices, and smooth pillow-like piles of snow were observed near Crystal Mountain on 4/11 and can help you to identify wind-loaded slopes.

Avalanche Discussion

Observations were limited on Monday, but the sun was definitely out and temperatures started a climb that should continue throughout the week. Many aspects have been receiving direct sunshine and should be going through a melt-freeze cycle due to cool nights and warm sunny days, creating a firm surface crust. This crust will grow thicker throughout the week, but below it you will still be able to find cold dry snow. As the snow surface softens throughout the day on these sunny slopes, expect a continuation of the springtime shedding cycle that started on Sunday and is expected to produce wet avalanches, snow falling off trees or rocks, and cornice collapses. This cycle will go through peaks and valleys over the next week as sunshine, freezing levels, and cloud cover fluctuate with the springtime weather. 

On slopes that do not see direct sunshine, a colder and more layered snowpack exists. The 4/7 and more prominent 4/9 interface should act as snowpack markers for you and we expect all avalanches to occur above the 4/7 interface, whether they are wet or dry.

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