Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Low danger doesn't mean no danger. Although unlikely, you could still find instabilities in last weekend's storm snow if you are traveling on shaded aspects or in extreme terrain. You'll need to contend with early-season travel conditions, particularly down low.

Problemi valanghivi

  • Wind Slabs

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

    A couple of warm sunny days separate us from our last snowstorm, helping to heal the snowpack and limit slab avalanche potential. We haven't had a reported avalanche in the zone since the storm, but have seen plenty of evidence that the wind transported snow at mid and upper elevations. If there are any lingering slabs left, it will be on a wind-loaded feature. Focus your attention on shaded aspects containing convex or unsupported slopes, confined rocky chutes, or cliff bands. Even a small avalanche can end your season in high-consequence terrain or when early-season conditions are involved.

    (12/8/2024)

    Cracking of the snow surface in wind-drifted terrain on Mt. Snoqualmie. A red flag sign of wind slabs.

    Photo: Benjamin Pontecorvo

Avalanche Discussion

Wednesday should be fairly similar to Tuesday with a few key differences:

  1. It will be warmer overnight Tuesday into Wednesday morning. Because of this, you may find that less of a surface crust exists in the morning on southerly aspects.
  2. It will be cloudier. Less direct solar influence will be exerted on the snow surface, helping to keep wet loose activity at bay.
  3. It will be cooler. Freezing levels are on a slow downward trend. We're not exactly throwing the mountains back into the freezer, but we're not dealing with those 9,000 to 10,000-foot freezing levels anymore.

These weather changes combined with limited reported avalanche activity give us some confidence to drop the official Wet Loose problem for Wednesday. However, if the forecast busts and bright sunshine is baking those southerly slopes and you see new rollerballs, head for shadier aspects.

Conditions around the Pass have become aspect and elevation dependant this week. Southerly slopes are thinner and heavier than shaded aspects where you can still find cold dry snow. Naturally, snow depth increases greatly as you ascend in elevation. On Monday, avalanche professionals missioned toward upper elevations in the Alpental Valley and reported ~90 inches of snow at 5100'. For comparison, NWAC forecasters found roughly half that amount (~45 inches) a few drainages over at 4400'. Snowpack tests showed that a layer just above the 12/7 melt-freeze crust produced failures, but the only reported avalanches were shallow slabs on Mount Snoqualmie the day of the storm. Down low, inversion conditions have kept things cool, but snow depths just aren't beefy enough to meet the threshold for consequential avalanches.

The lack of reported avalanches may be a result of difficult access to the mountains. Early-season coverage is the story at lower elevations. You'll need to manage hazards such as dirt, ice, exposed rocks, open creeks, holes, and bushes if you want to reach snowier slopes.

Regioni coperte