Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist last year abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

It may still be easy to trigger avalanches in wind-drifted snow, and conditions may be challenging to assess due to shifting wind directions. Stick to wind-sheltered and lower-angle terrain. Avoid steep slopes at upper elevations, below corniced ridgelines, and exposed to winds that sweep across the terrain. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Look for easterly winds to actively blow snow and form fresh drifts. This will indicate some of the areas where you can trigger avalanches. Wednesday's wind slabs will be complex as you can still trigger slides from westerly winds that transported snow since Monday. Look for more dominant cornices overhanging these slopes and use your probe or pole to feel for stiffer snow under the surface. Recent avalanches or cracking shooting from your equipment are signs to avoid slopes over 35 degrees. Due to the complexity of the conditions, it's best to avoid steep, wind-loaded terrain, especially at upper elevations.

    On Wednesday, winds will shift to the east and continue to drift snow. On the 17th and 18th, westerly winds intensified after subtly forming wind slabs over the past 10 days. This week, there have been a several close calls and a handful of avalanche involvements with wind slab avalanches. Most of these were in neighboring zones, and no injuries have been reported.

Avalanche Discussion

On the 18th, Stevens Pass Patrol reported easily triggered wind slab avalanches, ~6 inches deep, on the leeward sides of ridges and resulting from westerly winds. The biggest avalanche was D1.5. They also reported natural and human-triggered avalanches in the recent snow in neighboring backcountry terrain. Stevens Pass picked up 4-5 inches of snow since the 17th.

We're experiencing a multi-day period of incremental storms, accompanied by periods of strong winds. In the Stevens Pass area, you can find 2.5-3 feet of settled storm snow that has accumulated since March 9th. Recently, NWAC forecasters and other observers have reported reactive wind slabs failing on mid-storm interfaces. Dry and wet loose avalanches have been common on shady and sunny slopes, respectively. In all, over 20 avalanches have been reported in this and surrounding zones, including at least four avalanche involvements.

The snowpack underwent a major transition since the atmospheric river (AR) storm of February 21-25th. This AR crust is now buried over 4ft deep above 5000ft. You'll find a number of crust and old snow layers resting above this crust. On most slopes, the recent snow since the 9th is sitting on a crust from warm temperatures and sun. On high elevation, northerly aspects, there's a chance that you could find weak snow (buried surface hoar or possibly facets) at the March 9th interface, 2.5-3 feet below the surface. On the 10th, observers in the Foss River drainage reported triggering isolated avalanches, which are suspiciously indicative of this weak layer.

If you make it into the backcountry, please share with us what you find by submitting an observation HERE or on the Avy app. 

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