Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

A fresh coating of snow will cover the saturated snowpack, with about a foot of new snow at higher elevations, and closer to a few inches in below treeline areas. Evaluate the snow as you travel and pay attention to obvious indicators like recent avalanches as hints to stay off steep slopes, as we're not quite sure how well the new snow will stick to the old snow layer. Wind will have redistributed snow into drifts, which is where you're most likely to trigger an avalanche so steer around steep, wind-loaded pockets of snow. 

Lawinenprobleme

  • Wind Slabs

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

    There are a lot of different ways that this new snow avalanche problem could play out, so it's important to start the day conservatively and assess the snow as you travel. The most likely avalanche problem that you'll encounter is wind slabs, as strong winds will quickly shift new snow into reactive drifts overnight and into the day. These drifts are expected to be larger and more reactive the higher you go. Depending on how much snow ends up falling at higher elevations, drifts could be two or more feet deep.  Smaller wind slabs at lower elevations could be the only areas where snow is deep enough to produce a large enough avalanche to take you for a ride.

    Feel for changes in the snow as you travel. If snow quickly gains depth, or becomes firmer you've probably stumbled across a wind drift. You can also spot thicker, pillowed-looking snow deposits. You may see active wind loading, as winds will decrease but continue throughout the day. Search for these drifted locations around rocky outcroppings, just below ridgelines, and in gullies.  Avoid wind loaded pockets on terrain greater than 35 degrees during your outing. 

     

    Expect to find reactive wind loaded pockets beneath ridgelines and on steep convexities on Wednesday. 

    Photo: Greyson Herdman

Avalanche Discussion

Wednesday is the first day of a shift back to winter, and we don't really know how things are going to be looking out there. A highly variable 8 inches of rain fell in the West Central zone since Dec 23, saturating the snowpack thoroughly. Lingering wet snow concerns could continue to exist for the next few days. Large glide avalanches may still release on smooth rock or low shrub surfaces. If you see glide cracks near the top or middle of a slope, water is still moving through the snowpack and weakening bonds and an avalanche could release.  Avoid traveling beneath glide cracks.  Wet loose avalanches may run in damp lower elevation snow as well.  

We suspect that the wet snow surface and initial moist snow falling will hopefully mean that the interface between the new and old snow layer will be strong, and the continuing cooling temperatures will lead to a right side up, more stable new snow layer. We're not certain about this however, and the new snow may end up sliding easily on the soggy interface. If this is the case, any areas where the new layer is nearing 6 inches deep could slide in steep areas. Using small test slopes and pushing snow down to see if it slides easily on the old snow layer would be the best indicator of whether this might be a concern for your day. If it is, avoid steep slopes where enough new snow exists to cause a problem. 

Conditions will be out of the ordinary on Wednesday. At lower elevations where the snowpack is only a few feet deep you can expect to sink to the ground on feet. Even as you gain elevation you'll still probably sink pretty far into the snowpack. Creeks will be raging, and unsuspecting holes will be present in the snow. The new snow layer will likely insulate the "warmer" snow beneath it, keeping the wet layer soft at least for a few days. Eventually the old surface should firm up a bit. As temperatures cool, water drains from the snowpack, and snowfall intensity backs off during the day we may finally be seeing a downward trend in avalanche activity after a wild and busy period in the last week. 

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