Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

If you capitalize on the sunny weather to head to the mid and upper elevations, keep your eyes open for clues that nearby terrain could harbor wind deposited snow. Steer around smooth pillow-like drifts on steep and convex slopes and below sharp cornices. 

Problemi valanghivi

  • Wind Slabs

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

    You may encounter two distinctly different wind slab problems Wednesday. Older wind slabs formed during Monday’s storm still linger on many exposed slopes. Due to the extreme nature of the winds, expect erratic loading patterns with drifts well below ridgeline and along the sides of mid-slope features. You may find these firm older slabs more difficult to trigger. When you see textured snow surfaces or feel firm hollow snow, steer away from very steep and convex terrain. Normally, we would worry about the east winds building new wind slabs on west-facing slopes, however, there may not be soft snow left to move. If you see blowing snow or plumes along ridgelines, take note of where the wind deposits the snow, and steer away from steep slopes near ridgecrest on these specific aspects.

    (11/28/2020) Example from near White Pass: Textured surfaces like this indicate wind loading on nearby slopes.

Avalanche Discussion

Wednesday looks like a battle between the cold easterly flow and warm air pushing in from the west. We think the cool east winds will control the day. However, for locations west of the Pass, you could see the warm air and sunshine cause loose wet avalanches. Signs like new rollerballs and snow shedding from trees can clue you in that it’s time to seek our shadier slopes. 

The current snowpack is generally strong. We expect any avalanche activity to stay within the recent snow and the newest interface. At Hyak on Sunday afternoon avalanche professionals found surface hoar on a variety of slopes. Similar observations were made in the  Chiwaukum, Teanaway (E.Central), Tattoosh, Crystal, and White Pass  (W.South) areas. You’re most likely to find buried surface hoar on shaded sheltered aspects in the eastern portion of the forecast region. This could allow you to trigger avalanches more easily or for an avalanche to break widely.. 

Expect the height of snow to change dramatically as you ascend in elevation. Snow depths near Pass level and further east may only be 2-3’ (60-90cm), but above 4000’ the snowpack increases dramatically. Watch out for buried logs, open creeks, and numerous small trees that could put a quick end to your season.

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