Bollettino valanghe

West Slopes South

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

All these small storms are starting to add up and slowly increase avalanche potential heading into the weekend. On Friday, you could find locally higher avalanche hazard on the volcanoes where over a foot of new snow fell on Thursday. Look for red flag signs of instability and avoid likely trigger points such as convex features over 35 degrees or wind-loaded slopes.

Problemi valanghivi

  • Storm Slabs

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

    Continued snowfall into Friday, combined with fluctuating freezing levels, will maintain concerns for slab avalanches at mid and upper elevations. Slabs should be larger on the volcanoes or in wind-loaded terrain. Use small test slopes and uptrack tests to determine how the new snow is reacting to your weight. Take a moment to dig down to the topmost crust to look for potential failure points. If you find heavy snow over weaker snow, see shooting cracks, or blocks of snow failing in your tests, default to lower-angled terrain.

    Winds should be more robust on Friday than on Thursday, meaning there could be more wind slabs, especially near the crest. Look for them on the leeward side of ridgelines or near rocky features such as confined chutes or the base of cliffs.

    (1/4/2024)

    The crown of a large natural avalanche that occurred in the neighboring Snoqualmie Pass zone. It failed during a period of warm temperatures on Thursday. [SS-N-D2-R2-O]

    Photo: Alpental Pro Patrol

Avalanche Discussion

This week's pattern should continue on Friday. Expect another couple of inches of fresh snow, the possibility of a bump in freezing levels, and plenty of wind. Be on the lookout for rollerballs and small wet avalanches if you experience rain falling on dry snow.

On Thursday, roughly a foot of new snow blanketed Paradise, while areas closer to the crest received significantly less. This comes on the heels of approximately 2-4 inches of fresh snow on Wednesday. While most of these storms haven't been significant snow producers, they have been consistent. By the time the main event arrives on Friday night, we will be close to a foot of new snow over the 12/30 crust near the crest and potentially closer to 2 feet at Paradise.  

As we roll into a stormy couple of days, there are several interfaces in the upper snowpack to consider. Here’s some information on them, starting with the deepest:

  • Solstice Crust (formerly known as the 12/22 interface): The deepest layer of concern. It is roughly 1-1.5 feet below the surface. We do not anticipate any avalanches below this crust/facet sandwich and few to occur at it. 
  • 12/25 crust: The next significant crust above the 12/22 complex. This layer has been producing propagating test results in recent days. NWAC and professionals have identified buried surface hoar above this layer. We'll have our eye on it as the storm rolls in Friday night.
  • 12/30 crust: Easily identifiable crust less than a foot below the surface. It should be the sliding surface for most avalanches in the coming days. 
  • 1/2 interface: A layer of buried surface hoar may exist an inch or two above the 12/30. Where it exists, avalanches breaking on this layer could span far distances or wrap terrain features. There also may be near-surface facets in this vicinity.
  • 1/4 crust: A new crust may have formed on Thursday due to a brief warm-up. Its stoutness will depend on how cold it gets Thursday night and Friday.

Reported avalanche activity has been limited in previous days, but we anticipate it to slowly climb as we load these layers. Your most significant concern at lower elevations will continue to be travel hazards. Most open creeks and holes can be easy to spot, but not all. Travelers have been surprised by creeks that they never knew existed since we ordinarily play in a  deep winter snowpack. Stay vigilant out there.

Regioni coperte