Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

New snow and strong winds will increase the avalanche danger on wind-loaded slopes. Fortunately, the storm will give you clues to help you anticipate areas you want to avoid. Look for blowing snow, fresh cornices, and sharp drift that all point toward the potential hazard.

Lawinenprobleme

  • Wind Slabs

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

    Strong and gusty W-NW winds will easily build fresh slabs in some unusual spots. In some cases, they may overlay firm crusts. This could cause slides to trigger easily or run quickly. So, pay attention below sharp ridgelines, in the tops of chutes, near the base of cliffs, or along mid-slope gullies where you’re most likely to find a smooth pillow-like drift. Steer around these wind-loaded pockets and seek out less wind-affected areas. While we expect these avalanches to stay relatively small, you could encounter slabs 1ft thick that could easily flush you down a couloir or over a cliff. 

    (1/20/2023)

    Example: A  Wind Slab avalanche that was observed on Mt. Adams on 1/20. Note its location below a ridgeline and originating at the base of rocks.

    Photo: Paris Gore

Avalanche Discussion

This isn’t a very big storm, but when you combine the new snow and wind, it’s easy to see how the avalanche danger will increase. The West South zone could receive 4-10 in of snow, with the highest totals near the volcanoes. Since the storm will be at its worst during the overnight and morning hours, expect the most dangerous conditions over that same time period. 

This new snow will fall on a variety of surfaces including crusts, surface hoar/facets, and settled powder that were observed on Thursday by NWAC forecasters and avalanche professionals. Use small slopes and hand pits to test the bond of the old and new snow. Since we’re expecting temperatures to cool, outside of wind-affected terrain, the snow should become mostly right-side-up. This could result in a few small loose slides running on the underlying crusts but should limit slab avalanche activity. 

Prior to this storm, the upper snowpack consisted of 1.5-2.5 ft (45-75cm) of settled snow over the very prominent and stout MLK crust. While you can still find older layers (1/21 and 1/18 interfaces), we’re mainly concerned with avalanches failing at or near the base of the new snow (1/26). At the lowest elevations, rain will fall and could continue to produce a few rollerballs and small loose wet slides. However, the snowpack in these areas has been through a lot and should easily handle the additional water without much issue.

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