Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Areas of the West South near the Cascade crest are primed to lose their cool winds and be thrown into the oven on Friday. Take note of changing conditions throughout the day and avoid slopes steeper than 35 degrees if you encounter wet and weak snow surfaces. At middle and upper elevations, be aware of wind-drifted piles of snow where you could trigger an avalanche more easily.

Problemi valanghivi

  • Loose Wet

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

    The cool east winds and high clouds have kept most of the Wet Loose activity at bay the past few days for many areas near the crest in the West South. With these winds ready to decrease on Friday, we could finally see the day where warm temperatures and solar input are able to destabilize the snow and cause some Wet Loose avalanches or cornice failures. This process has reportedly already begun in many areas of the Cascades along with areas within the West South zone such as the volcanoes. If you find yourself in the sunshine and see new rollerballs or find the snow surfaces becoming wet and sticky, head for shaded terrain and be aware of the terrain above you.

    (11/27/2020) Pinwheels at Mt. Rainier after rising freezing levels and the sun came out a few days after a storm. [S aspect 5400']

  • Wind Slabs

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

    The wind was certainly ripping the past few days along the crest within the West South. Because of this, we can’t rule out the possibility of you encountering a lingering Wind Slab at middle and upper elevations on Friday. Oftentimes with East wind events like we just experienced, loading patterns may be different than you are used to, so pay attention as you travel to see where the snow may have been transported to. You can look for smooth pillow-like piles of snow or textured surfaces to help you clue into wind deposited areas to avoid.

    (12/2/2020) Strong easterly winds transported snow forming new slabs in some unusual areas. Picture: Porter McMichaels, CMSP.

Avalanche Discussion

It’s been a battle between warm and cold the past few days in the West South and there have been mixed results. Areas near the crest have remained relatively cool due to cold east winds, while other areas not as prone to these winds warmed up quite a bit. We are another day removed from the new snow and following wind events earlier this week, but instabilities may still be present. With the loss of the east winds and freezing levels heading toward 11,000 feet, Friday may finally be the day warm wins over cold and creates some avalanches. 

A generally strong and deep snowpack exists around the West-South zone. The height of snow near treeline typically ranges from 4-6’ (120-180cm). We expect any avalanche activity to occur within the recent snow or on the new interface (11/30). Observations from the Tattoosh, Crystal, and White Pass areas Sunday reported surface hoar prior to this week's storm. Wednesday an NWAC forecaster confirmed surface hoar in a snowpit near Crystal. However, so far, we have not heard of any avalanches on this layer. If you dig in the snow on shaded sheltered slopes let us know what you find by submitting a public observation.

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.

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