Quick report
- Red Flags
- Recent Avalanches, Cracking, Collapsing, Poor Snowpack Structure
- Red Flags Comment
- <p>We experienced very localized cracking and collapsing from 8000' - 8400' and went looking for a more cohesive slab. More below -</p>
Snowpack
- Instability Comment
- <p> </p> <p><strong>We remotely triggered a 10-16" deep and 60' wide soft slab avalanche on a NE facing slope at 8700' that failed on the PWL</strong>. The slope was less than 35 degrees and so the "avalanche" ran perhaps a foot downhill at most. </p> <p> </p> <p><strong>It's likely that there may be a "sweet spot" for instability on northwest to east facing slopes at the mid-elevations. </strong> (West may also be at play but there is some uncertainty here.)</p> <ul> <li>At the <strong>low elevations</strong>, <em>very weak</em> <em>faceted snow exists</em> but there doesn't seem to be much of a snow/wind load above to create a cohesive slab except in isolated terrain (that perhaps has seen more wind).</li> <li>At the <strong>high elevations</strong>, <em>weak faceted snow exists</em>, but there is a lot of uncertainty as it is capped by spatially variable wind crusts.</li> <li>At the <strong>mid elevations</strong>, <em>very weak faceted snow exists</em> and there are increasingly more places where the overlying slab has consolidated due to wind and settlement. </li> </ul> <p> </p> <p>As we know, you need a few ingredients for an avalanche: a slab, a weak layer, a slope steep enough to slide, and a trigger. </p> <p>Extended Column Tests - ECTPV (full propagation on isolation) from 8200-8400'.</p> <p>Now the set-up is that the weak layers are easy to find: Jan/Feb drought layer facets (PWL) are buried 6"-2' (wind drifted areas) down and are LOOSE, grey, angular - the photos below make them easy to spot. Sometimes they sit above a crust, sometimes they don't. </p> <p>Looking for a slab, however, can be very tricky for many reasons. </p> <ul> <li>It may appear that there is no slab because much of the top snow is "powder snow"; but in reality it may be the couple/few inches of snow directly above the facets may have consolidated enough to propagate a slab avalanche. </li> <li>Wind loading and snowfall patterns have been erratic and it is not necessarily possible to extrapolate one northeast facing slope at a certain elevation with another....even in the same drainage. </li> <li>In essence, the weak layer hunting is easy and obvious - it's now that the slab hunting is tricky...and potentially dangerous. </li> </ul> <p> </p> <p>Again, it may be that the mid-elevation polar aspects may be the sweet spot for avalanche activity. </p> <p> </p> <p><strong>Last point: </strong> conditions are variable, tricky, and dangerous in some areas. Collapsing and cracking may not be evident until you trigger the avalanche. Low angle skiing/riding (with no overhead hazard) is excellent without all the uncertainty and avalanche danger. </p>
Best skiing and riding in two months, and not by a little. 10-14" of settled snow sits above the Jan/Feb drought layer PWL. Best and safest skiing exists on low angle shady aspects with no overhead hazard.