Lawinenlagebericht

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Northwest Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

At upper elevations, maintain caution around shallow wind drifts or where loose snow could push you into unintended terrain. At lower elevations, milder temperatures improved stability over the past 24 hours, but continued warming will reverse that trend on Sunday. Reduce your slope angle if you encounter sticky snow where you can trigger a shallow avalanche on slopes steeper than 35 degrees.

Lawinenprobleme

  • Wind Slabs

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

    Winds picking up into the moderate range will transport limited amounts of snow at upper elevations and on shaded aspects where the snow stays colder and drier. Milder temperatures have been reducing the snow available for transport through consolidation and crust formation (S aspects). As you transition into colder, drier, and lower-density snow, pay increasing attention to signs of active or recent transport. These include blowing snow, drifts covering your tracks, denser layers that crack as you travel, or cornices with a fresh, sharp lip. Steer around steep terrain features near ridgelines, the base of cliffs where snow may pile up, or unsupported mid-slope features where the snow looks especially rounded and thick. These slabs may lose reactivity as temperatures continue to warm throughout the day.

    Dry loose avalanches were moving in very steep terrain on Saturday although warming temperatures may limit this potential by the afternoon.

  • Loose Wet

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

    Recent snow above the 2/13 crust will susceptible to warming temperatures on Sunday. The freezing level could be above the Ridge by the late morning with moist snow surfaces developing on all aspects. As the snow becomes sticky and wet or you start to see rollerball activity on surrounding slopes, wet avalanches become a possibility. These avalanches could entrain the 3-6" of consolidating snow on the 2/13 crust and could run effectively on the crust. Terrain traps, creeks, cliffs, or other obstacles on the slope below you would amplify the impact of a small avalanche.

    (2/18/2023)

    Wet loose from Snoqualmie Pass. Similar avalanches are possible at Hurricane Ridge on Sunday.

    Photo: Irina Kopyeva

Avalanche Discussion

Snowfall has been trickling in over the last few days at Hurricane Ridge. Saturday featured cloudy skies and light snowfall. Temperatures warmed during the mid-day hours with several inches of snowpack settlement helping reverse some of the faceting snow near the surface and improving the bond with the 2/13 crust. This interface remains worth checking before moving into more committing terrain, because consolidation of the top 4-6" of snow may have formed a slab.  Expect a thin crust on SW-S-SE aspects by Sunday and a temperature skin may extend around the dial.  

On Thursday, professional observers found 4-5" of low-density, right-side-up, and faceting snow sits above the 2/13 crust complex.  Winds were effectively redistributing the snow (see video) into drifts up to 15" deep, while isolated slopes were scoured to ice. Ridgelines were scoured bare in many places while trees had lost most of their snow. The 2/13 crust complex has a breakable 1 cm upper crust, 2 cm of faceting dense snow, and a 2 cm fully supportable lower crust.  This faceted sandwich could come into play in a future loading event. The 2/3 crust/facet interface sits 35 inches or more below the snow surface. Avalanche professionals continue to get some reactivity in test results under this crust, but it is not currently a concern for human-triggered avalanches given the thickness of the 2/13 crusts.

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