Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

The weather Saturday will likely create dynamic avalanches conditions with the hazard increasing throughout the day. You may trigger avalanches in places the wind drifts the snow into slightly firmer and thicker slabs. Blowing snow and textured surfaces will help point out wind-loaded features you want to avoid.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    While the snow totals in this storm might not sound impressive, when you combine the new snow with moderate to strong winds, you can expect new wind slabs to form. First thing in the morning any slab may be too thin to really pose much of a risk. However, as the day goes on these possible avalanches will become thicker and more common. Fortunately, the storm will provide some pretty obvious clues. Blowing snow, textured surfaces, and firm smooth drifts can help you identify which aspects and features might hold new slabs. You may find these small avalanches below the ridgeline, on steep convex rollovers, at the tops of chutes, and near the base of cliffs. If you start to find smooth frim pillow-like drifts steer around them, especially in high consequence terrain.

    (3/9/2022)

    Example: Wind lips and firm pillow-like drifts along wind-exposed convex features. 

    Photo: Andy Harrington

Avalanche Discussion

A storm should arrive at Snoqualmie Pass in the wee hours of Saturday morning. Initially, mild temperatures and a relatively warm snow surface from Friday should help the new snow bond well to the older snowpack. As temperatures cool and the snow starts to accumulate, expect the danger to rise. Even though this storm seems rather mundane, there are two sources of uncertainty. 

  1. 3/8 Facets/Early March Crust: We’ve been tracking the 3/8 facets over the Early March Crust for quite some time. Recent observations by NWAC staff and avalanches professionals found these weak grains to be moist and not producing significant snowpack test results below 5000ft. However, on Friday an avalanche professional witnessed a treebomb trigger a small (D1.5, see photo) avalanche on the 3/8 Facets above the Cache Couloir. (N aspect, 4400’) So far, this is the only known avalanche on this layer in this zone. Slides like this leave us scratching our heads and speak to the highly unpredictable nature of persistent weak layers. While we don’t think this is currently a common problem at the Pass, it's worth taking this unlikely possibility into account, especially if you travel in complex terrain or ascend to higher elevation slopes. 
  2. A Puget Sound Convergence Zone will likely form Saturday afternoon. Predicting where this firehose of moisture will aim is quite tricky. You could find yourself under locally heavy precipitation. If that occurs, remember natural avalanches frequently occur during similar conditions. This could lead to higher danger than forecasted. 

At lower elevations, this storm will start out as rain. However, the below treeline terrain snowpack has seen plenty of water and some recent sunny days. So, while we can’t rule out an isolated wet avalanche in very steep and rocky terrain, these should not be common. Cooling temperatures should quickly put an end to any wet avalanche concerns. 

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