Avalanche Forecast
Issued: Jan 27th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
astclair,
Avalanche Canada
Lingering pockets of wind-drifted snow at higher elevation remain a concern for Tuesday. Seek out sheltered slopes and watch for reactive wind slabs around steep rolls and ridge features.
Summary
Confidence
Weather Forecast
Monday night: Cloudy, isolated flurries, light to moderate southwest winds, alpine temperature -7 C.
Tuesday: Mix of sun and cloud, isolated flurries, light southwest winds, alpine high temperature -4 C, freezing level around 1400 m.
Wednesday: Mix of sun and cloud, moderate southwest winds, alpine high temperature -3 C, freezing level around 1400 m.
Thursday: Mostly clear, light southwest winds, alpine high temperature -1 C, freezing level around 1500 m.
Avalanche Summary
Several recent natural, large (size 2-2.5) wind slab avalanches were reported on over the past 48 hours on northwest through northeast aspects.
On January 16th, a natural, size 2 wind slab stepped down to the deep persistent basal facets below a rock band, details here.
Snowpack Summary
Recent strong west and southwest winds have formed stiff wind slabs on lee and cross-loaded terrain features at upper elevations.
A crust can be found up to treeline and on solar aspects in the alpine due to previous warming and sun exposure.
A well consolidated mid-pack overlies a generally weak basal snowpack. The bottom 10-20 cm of the snowpack consists of facets and deteriorating crusts. Although inherently weak, the benign weather pattern this week will likely promote a decreasing trend in reactivity for this avalanche problem. Areas that are most likely to harbor this problem are shallow, rocky start zones.
Terrain and Travel
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Wind Slabs
Strong southwest winds have blown recent snow into stiff wind slabs in lee and cross-loaded features at alpine and treeline. Natural activity may have subsided but human triggering remains possible.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Mild temperatures are helping the basal weak layers to adjust and the snowpack to strengthen. Deep persistent slab avalanches on these layers are unlikely but may still be triggered from shallow snowpack areas near rocky outcroppings.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 28th, 2020 5:00PM
