Avalanche Forecast
Regions: Glacier.
The weak basal facets and persistent weak layers within the upper snowpack continue their lurking ways around Rogers Pass.
Keep sticking with your conservative program; ride supported terrain, respect others by not dropping in on top of them, and come home safe.
And if you're skiing on glaciers, the thin snowpack is barely hiding open crevasses. Travel with care!
Confidence
Moderate
Avalanche Summary
On Wed a field team today triggered a couple of size 1.0 slab avalanches on small convex rolls at treeline - one of these failed on the Jan 3rd surface hoar layer down 35cm.
In neighboring areas there are continued reports of isolated human triggering of the recently buried surface hoar layers, as well as natural/explosive triggering of the deep persistent facet layer.
Snowpack Summary
Recent warm temperatures have left a melt-freeze crust at or near the surface below ~1600m.
Two surface hoar (SH) layers, present in the upper 40cm, are potential failure planes in areas where the surface snow has become slabby (ridgecrests, immediate lee features).
The mid-pack facets are slowly rounding and gaining strength, while the basal facets and Nov 17 facet/SH/crust weakness are still reactive when isolated in snowpack tests.
Weather Summary
-ahem....- is anyone awake in the weather-making department? A minor blip of snow and gusty SW winds on Sat, but otherwise much of the same mix of cloud, flurries, and light winds.
Fri: clouds with sun, nil snow, Alp high -5*C, 800m FZL, light W ridge winds
Sat: flurries, 10cm snow, Alp high -4*C, 800m FZL, mod/gusting strong SW winds
Terrain and Travel Advice
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Avalanche Problems
Persistent Slabs
The Jan 3 surface hoar (5-10mm) is buried ~40cm and is more reactive at ridgeline or in open lee features, where wind has stiffened the surface. If triggered, this slab has the potential to step down to the deep persistent layer.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 2.5
Deep Persistent Slabs
The Nov 17 layer, which consists of a faceted crust and decomposing surface hoar, highlights a weak basal snowpack.
Be particularly cautious in steep, rocky areas with thin snow coverage, where the majority of the snowpack is weak and faceted.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 2 - 4