Avalanche Forecast
Regions: Glacier.
Wind slabs, on top of persistent slabs, on top of a deep persistent slab...this isn't a delicious layered cake from your local bakery.
This "house of cards" snowpack cannot be treated like a normal year. With so many lingering weaknesses, sticking to supported slopes with limited overhead exposure is paramount.
Confidence
Moderate
Avalanche Summary
A field team on Connaught/Lookout triggered a sz 1 wind slab on Monday, which stepped down to the Jan 3 surface hoar. They also observed several sz 1 loose/dry avalanches on the N Face of MacDonald, running in extreme terrain.
Cheops North 4 ran sz 2 Monday morning, while Frequent Flyer ran sz 2 on Sat into the creek.
Crossover ran sz 2.5 onto its fan Tues morning.
Snowpack Summary
Reactive wind slabs are popping out at Tree-line and Alpine elevations, stepping down into the Jan 3 persistent weak layer.
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
Cloudy skies, gusty winds, flurries, and a slight warming Wed/Thurs summarize the weather picture.
Tonight: mainly cloudy, Alp low -8*C, moderate gusty W winds
Wed: mainly cloudy, isolated flurries, Alp high -4*C, 1500m FZL, moderate gusty W winds
Thurs: flurries, 5-10cm snow, Alp high -3*C, 1300m FZL, moderate gusty W winds
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Avalanche Problems
Wind Slabs
Strong S/SW winds from Sun/Mon formed wind slab at Tree-line and Alpine elevations.
These slabs are particularly reactive on convex rolls at ridge-line, lee areas, and cross loaded features.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Persistent Slabs
This layer is buried ~40cm and will be most reactive at ridgeline or in open lee features where new wind slab has formed on top of it. If triggered, this slab has the potential to step down to the deep persistent layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
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 cautious in steep, rocky areas with thin snow coverage, where the majority of the snowpack is weak and faceted.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 2 - 4