Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Expect the avalanche danger to rise through the day as new snow and wind build unstable conditions at mid and upper elevations. Use extra caution on steep slopes near and above treeline where the wind deposits pillows of snow. The new snow fall on weak surfaces.

Lawinenprobleme

  • Wind Slabs

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

    Use caution on wind-loaded slopes that are 35 degrees and steeper. Steer around convex rolls, thicker pillows of snow, and slopes with drifted wind features. The most likely places for these avalanches are immediately on the leeward sides of ridges and terrain features. 

    Watch for southwesterly winds to transport incoming snow. Other signs that you can trigger an avalanche include cracks shooting through the snow and recent avalanches on similar slopes. You can dig quick test pits or use small test slopes to see how easily the snow slides before committing to bigger terrain.

     

    (12/19/2021)

    A crown from an avalanche (size D2) near Stevens Pass. This ran on 12/18 in wind affected terrain. Above treeline, NW, Chiwaukum range

    Photo: Matt Primomo

  • Storm Slabs

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

    Watch for cracking in the snow or small test slopes that slide easily in the new snow. You can easily assess this avalanche problem with quick snow pits or by testing inconsequential slopes. If you see these signs of instability or fresh avalanches, steer around convexities and use cautions on slopes steeper than 35 degrees. The new snow may be falling on some weak surfaces, including surface hoar.

    Be alert to changing conditions. Triggering storm slab avalanches could become a concern by the end of the day and near the top of Washington Pass. First thing in the morning and further east, these avalanches may not be an issue.

    (12/20/2021)

    A storm slab avalanche that ran on the 18th on a northerly aspect in the Hairpin valley. You could encounter similar slides on Wednesday.

    Photo: Adam Butterfield

Avalanche Discussion

Expect avalanche conditions to change throughout the day and as you move through the mountains. The danger may be minimal first thing in the morning but could increase if a foot or more of new snow accumulates with gusty wind at upper elevations. There's uncertainty with the amount of precipitation expected during this storm. Additionally, southwest to southerly winds may produce varying degrees of transport at different elevations. On Monday and Tuesday, observers reported finding surface hoar on Delancey Ridges and the Hairpin Valley, a typical location for the formation of weak grain type. 

A widespread cycle of avalanches occurred on Saturday, the 18th (up to size D2.5) in the Washington Pass area. A crust buried in early December can now be found roughly 4-5 feet below the surface, especially on slopes above 6,000ft. Observers continue to find varied test results on the crust including some that indicate the potential for triggered avalanches. 

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