Lawinenlagebericht

Olympics

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
Keine Stufe
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Veraltet — dieser Lagebericht ist 5 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Expect a pleasant spring-like day in the mountains with the flavor of avalanche activity highly aspect dependent. Steer around wind slabs on lee slopes and shaded aspects, but also pay attention for surface snow warming and destabilizing in the sunshine. Slick crusts and sliding falls may be your greatest hazard on Friday.

Lawinenprobleme

  • Wind Slabs

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

    You're likely to find around 3-4" of low-density snow at middle elevations with just enough W wind to form thicker drifts on the lee sides of ridgelines at middle and upper elevations. Sunshine on Thursday likely helped to neutralize some of these slabs on the southern half of the compass, so the majority of the reactivity is expected on typical N through E aspects. The depth of snow above the crust may increase more significantly at upper elevations, so note this change if it occurs and anticipate the potential for larger slabs on nearby slopes. Slabs will form opposite the scoured sides of ridgelines, where fresh, sharp cornices likely point to the hazard on steep slopes below. Steer around these areas. Utilize small test slopes to check for reactivity within thicker drifts and the potential for punchy layering. 

    Example: Wind stripped and wind sculpted ridgeline. Be suspicious of slopes where the snow depth is thicker above the crust.

    Photo: public

  • Loose Wet

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

    Friday should be the second day with ample sunshine following our recent storms, but increasing cloud cover Thursday afternoon may have left cold snow on some typically sun-exposed slopes. Slopes without rollerballs will be more primed for wet loose activity moving forward. It will also be warmer on Friday so expect thin surface crusts to break down where they exist. Most wet loose activity will run efficiently atop the 3/25 crust, but there may be enough coverage on many sun-exposed slopes for this crust to exist at upper elevation. The risk of wet loose avalanches may be more limited to gullies and W or E aspects at middle elevations. Gauge the depth of recent dry snow and expect snow to start shedding off warming rocks and gaining mass once sunshine hits the slopes. Avalanches could take you for a significant ride on longer steep slopes in parts of the Olympics with more than 6" of snow above the recent crust.

    Example: D1 wet loose on a sun-affected aspect near Hurricane Ridge.

    Photo: ONP Rangers

Avalanche Discussion

ONP Rangers traveled in Klahanie Bowl on Thursday. The 3/25 storm deposited 3-4" of low-density snow that is well bonded to a very slick (knife+ hard) crust. This crust presented the greatest hazard in the terrain and long, sliding falls were a real concern on anything steep. The crust is not bulletproof, and they rangers were able to boot back up to the ridgeline. There was plenty of wind-affected snow in the terrain, but slabs were localized to the lee sides of ridgelines at middle elevations and increased at upper elevations. They were able to easily initiate small slabs D0.5 in steep terrain, mostly running on the 3/25 crust. On some aspects, they encountered a sandwhiched crust, likely formed on 3/24 as snow fell on a warming trend and ended with a brief period of rainfall. Thursday started cloudy at Hurricane Ridge, but the sun came out through the early afternoon hours and initiated rollerball activity on sun-affected slopes before clouds increased in the afternoon.

We're not quite sure how 0.5" of water equivalent translated into only 3-4" of snow in the Klahanie Bowl area. This could be the nature of the wind direction. If you find areas with greater average snow depth, expect the size of wet loose and wind slab activity to increase.

We're expecting pleasant conditions and a spring-like day (warmer) day on Friday. Cold snow should remain on shaded aspects while south-facing aspects need another day or two to fully transition into a melt-freeze cycle.

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