Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

High snowfall rates, strong to extreme winds, rising temperatures, and known weak layers in the snowpack will result in very dangerous avalanche conditions on Wednesday. Although the largest avalanches are expected on the volcanoes, a weaker snowpack exists near the crest. Avalanches could run far distances well down into the trees, demanding that you avoid all terrain where they can start, run, or stop.

Lawinenprobleme

  • Loose Wet

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

    Rain will likely destabilize the snow surface at lower elevations and produce natural avalanches. Wet avalanche potential will peak shortly after rain begins falling on dry snow. Even if the height of instability for these avalanches has passed, don’t try to thread the needle. These slides could occur anywhere the snow surface is wet. The threat of very large avalanches coming down on you from upper elevations should have you avoiding all avalanche terrain. 

    (12/13/2023)

    Loose wet avalanche debris piles due to a rain on snow event earlier this winter.

    Photo: Dallas Glass

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2–3

    This next storm is going to wallop the volcanoes where several feet of snow is expected. Accumulations should be closer to a foot near the crest. Throughout the zone, rising temperatures during this event will result in the storm snow becoming “upside down.” Heavy precipitation rates and strong to extreme winds will help slabs build quickly and fail naturally. With known crusts and potential weak layers already in place, avalanches will undoubtedly be large enough to bury and kill you. In isolated locations, they could break into older snow layers, grow very large, and run close to full path on a firm crust. Wednesday is not the day to wander around the mountains anywhere an avalanche can start, run, or stop. 

    Widely breaking slabs at the base of cliffs on the west side of Mount Adams. These failed within the last week. Similar slides could occur on Wednesday.

Avalanche Discussion

Tuesday was a bit of a break between storms, but it may not have felt that way. Winds were ripping in the West South, and temperatures slowly climbed throughout the day. Observations from Crystal, Paradise, and White Pass all indicated that hard wind slabs were building throughout the day. The Crystal Mountain Pro Patrol triggered a few slabs on deeper layers in the snowpack (2/14 and EFC) with their mitigation work in Northway. 

On Wednesday, expect peak warming to coincide with the heaviest precipitation and strong to extreme winds during the daylight hours. It will be a very dangerous day to be in the mountains, particularly on the volcanoes. Avoid all terrain where avalanches can start, run, or stop - including well down in the forest.

On Monday, a cold winter storm dropped 1-2 feet of low-density snow, creating the 2/24 interface. Deeper in the snowpack, a series of crusts and pockets of weak snow exist above the stout Early February Crust (EFC). We are concerned about these layers becoming activated on Wednesday, which could result in 5-6 foot deep avalanches. In isolated locations, they could span far distances or wrap terrain features. We have had reports of very large slides on the volcanoes in the past week during loading events, including on Mount Adams, Mount St. Helens, and Mount Rainier. These are not avalanches you’re going to want to be anywhere near. They could break trees and will certainly be large enough to kill you, even if you’re far below where they start.

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