Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Reports of small natural and triggered slab avalanches from the past few days emphasize you can cause a slide if you travel onto steep wind-loaded features. Steer around smooth pillow-like drifts you see below sharp cornices, in the tops of chutes, or along the base of cliffs.

Lawinenprobleme

  • Wind Slabs

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

    Several days of snow and wind formed slabs on the lee sides of exposed features at mid and upper elevations. Unfortunately, a few inches of new snow may hide some of our normal visual wind slab observations. So, look for large clues like cornices and drifts to help anticipate wind-loaded aspects. If you notice one area has deeper snow, a firmer surface, or looks “fat” with a pillow-like drift, you’ve found the problem. You’re most likely to see these clues below cornices, along the base of cliffs, or in rock-walled gullies. Steer around these wind-loaded pockets by finding wind-stripped or lower-angled terrain. Even though we expect most of these slides to stay small, many could be large enough to take you for a ride, flush you down a couloir, or carry you over a cliff.

    (1/15/2023)

    A small human triggered wind slab from the Crystal backcountry Sunday. 

    Photo: Public Observation

Avalanche Discussion

The snow has started to stack up over the 1/14 crust around the West South zone. While it’s by no means deep, you may find 8-15 in (20-35cm) of snow at mid and upper elevations. Outside of wind-affected terrain, cooling temperatures and low snowfall rates should create a generally right-side-up structure that’s bonded well to the firmer crust. With this setup, you could see a few small loose avalanches in steeper terrain. Any slide (loose or slab) running on this crust could have the ability to move quickly and travel far downslope. 

On Monday, travelers in the Cyrstal backcountry reported a few small natural slab avalanche below a steep rocky rollover. These fresher wind slabs sit amongst older crowns and debris from wet slabs that failed last week. As the sun unexpectedly made an appearance around the zone, the new snow responded predictably with rollerballs and a few small loose wet slides. While we aren’t expecting sunshine Tuesday, if it pops out, you could see more of the same. 

A few additional inches of snow Monday night into Tuesday won’t do much to increase the hazard. Instead, it will only add to the upper snowpack, continue to improve travel conditions (hopefully), and potentially further hide frozen piles of avalanche debris. 

The upper snowpack consists of the new snow over the strengthening 1/14 crust. Below a layer of wetter grains dry snow continues to exist. Information about the recent 1/4 surface hoar layer is limited, but indications are that it became wet during last week’s rain event. So, while you may still find this interface in the snowpack, we don’t expect any avalanches on it at this time.

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