Avalanche Forecast
Issued: Jan 22nd, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
dsaly,
Avalanche Canada
Avalanche hazard is improving, but triggering avalanches in specific or isolated terrain remains possible. Be wary of lurking wind slabs and large cornices.
Summary
Confidence
Weather Forecast
Friday night: Cloudy with starry breaks / light north winds / alpine low temperature -18
Saturday: Mix of sun and cloud / light southwest winds / alpine high temperature -10
Sunday: Mix of sun and cloud, isolated flurries / light variable winds / alpine high temperature -12
Monday: Cloudy with sunny breaks / light variable winds / alpine high temperature -12
Avalanche Summary
Recent winds have formed stiff wind slabs in lee features at upper elevations that may be possible to human trigger.
On Wednesday, operators in neighboring Glacier National Park reported several large (size 2-2.5) wind slabs releasing naturally on a variety of aspects (north, east, and south). Two natural cornice failures were reported in Glacier National Park on Wednesday releasing above north-facing slopes.
This MIN from Clemina Creek last weekend reports that the Jan 11th surface hoar was cracking and propagating in sheltered treeline and below treeline areas where it was buried 40-50 cm deep. Now less reactive, this is a layer we will continue to monitor.
Since field observations in this region are limited, please consider submitting your observations to the Mountain Information Network.
Snowpack Summary
Recent winds have scoured snow surfaces, loaded cornices, and formed stiff wind slabs in alpine and upper treeline areas. These wind slabs sit over a variety of surfaces, including isolated surface hoar, sun crusts, and settling storm snow. Clear skies and cold temperatures are encouraging surface hoar growth and surface faceting.
A new sun crust may be forming on steep solar aspects, and there here have been reports of surface hoar growing on the snow surface.
40-70 cm of snow from the past week has buried a weak of layer of surface hoar that has shown reactivity in the north of the region. A MIN from Canoe Mountain on Tuesday reported a sudden pop or drop on this layer in snowpack test results. Observations are limited, so the distribution and sensitivity of this layer is uncertain and warrant careful assessment. Below 1600 m, 20-30 cm of snow is settling above a decomposing melt freeze crust.
Deeper in the snowpack, a couple of older persistent weak layers may still be identifiable from late and early December, consisting of surface hoar and a crust with faceted snow and buried anywhere from 100-200 cm deep. Prolonged periods of inactivity and unreactive snowpack test results suggest that these layers have trended towards dormancy.
Terrain and Travel
- Carefully evaluate steep lines for wind slabs.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Avoid exposure to slopes that have cornices overhead.
Problems
Wind Slabs
Recent winds have redistributed recent snow into hard wind slabs on lee features at upper elevations that may be possible trigger. Give cornices space, large cornices may trigger avalanches on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar buried Jan 11 may be found 40-70 cm deep on open, sheltered slopes near and below treeline. There is uncertainty as to the distribution and reactivity of this persistent slab problem across the region.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Jan 23rd, 2021 4:00PM
