The Bottom Line:  Friday we are expecting to see increasing NW winds around 15mph, gusting to 30. This will cause the new snow to drift into fresh sensitive wind slabs 1-2ft thick which are likely to be triggered by a human (Especially in cross-loaded gullies, and also S and SE aspects). These surface wind slabs could also step down to rain crusts or the ground in particularly weak areas, causing deep and deadly avalanches.

Thoughts on Risk Reduction:

Let’s take a step back. We now have a few serious weak layers deep down in our snowpack that you do not want to trigger. Your best bet to avoid a deadly avalanche is to reign in your expectations and lower your risk tolerance. Keep a wider-than-usual margin of safety by sticking to low-angle terrain, and giving dangerous areas a wide berth. There will be times later this spring when you can be more ambitious with the terrain… this is not the time.

Midpack Melt Layers and Crusts:

There is a serious weak layer about 60cm deep (The “Big Warmup” Layer, Formed Nov 17th). It is a thick refrozen crust with weak facets above and below. With the low predictability of this unusual weak layer, a wide safety margin is necessary. Slides could propagate further than expected.

Observations from the Chilkat Pass zone on 12/4 found moderate strength but easy propagation on failures within this layer. We know it to exist at all elevations above 1000ft — even up to the highest summits. We expect this layer (or other midpack crust-facet layers) to be an ongoing issue going forward.

Depth Hoar Formation (Above 3000ft in the Lutak zone):

October snow followed by long cold snaps created depth hoar at the ground in most areas above treeline. As the snow gets deeper, the load over this weak layer increases, as does the likelihood that you could trigger a full-depth slide. This is becoming a high-consequence early-season snowpack that deserves respect and should drive conservative decision making. Even “small” slides could have large blocks of hard slab and bury a person quite deep in a terrain trap.

Snow pit photo from Lutak zone 12/1, and profile from 11/26.

Wind loaded slopes and cross-loaded gullies should be avoided. You can tell if a slope is wind loaded by the filled-in, or rounded shape of the snow. Probe around for hollow, slabby surface snow. Minimize your exposure to these slopes, and always travel one-at-a-time through any suspect areas. Rocks will be a major safety hazard as well, so take it slow and easy, and keep your avalanche eyeballs on, especially in wind loaded areas and convexities. Be careful to avoid terrain traps!