Avalanche Forecast
Issued: Feb 10th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
MBender,
Avalanche Canada
New snow has gradually accumulated over the past week and has been redistributed by winds blowing from a variety of directions. As a result, wind slabs at upper elevations are the main concern.
Summary
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
Monday Night: Cloudy with scattered flurries. Moderate west wind. Alpine high temperatures around -10.
Tuesday: Scattered flurries. Moderate west wind. Alpine high temperatures around -6. Freezing level 1000 m
Wednesday: Mix of sun and cloud and isolated flurries. Light west wind. Alpine high temperatures around -5. Freezing level 1100 m
Thursday: Flurries. Light to moderate southwest wind. Alpine high temperatures around -8.
Avalanche Summary
Sunday's reports showed a few windslab avalanches running to size 1.5 in alpine terrain from a variety of aspects. There was also a report of a natural failure on a northerly aspect at 2500 m in the north of the region.
On Saturday there was a report of remotely triggered (from a distance) wind slab avalanche size 2.5 avalanche at 2350 m on a southeast aspect. The details can be seen in this MIN post. There were also reports of numerous loose dry avalanches running in steep terrain size 1-1.5.
Snowpack Summary
20-40 cm of snow accumulating last week sits over older wind-affected snow at high elevations, or over a widespread melt-freeze or rain crust with a variable upper extent of 1800-2000 metres in elevation. The recent snow has mainly shown reactivity where winds have had a chance to redistribute it into new slabs. A few reports from adjacent regions have shown poor bonding with the buried crust where it exists.
A weak layer of surface hoar may still be found about 90 cm deep around Golden and Kimberley, 50 cm deep around Invermere, and 130 cm deep along Kootenay Lake. Recent reports from the Golden area suggest a positive stabilizing trend. At lower elevations this layer has likely been bridged over by the above-mentioned crust.
The base of the snowpack contains basal facets. It remains possible to trigger these deep weak layers in shallow rocky start zones or from a heavy trigger such as a cornice fall.Â
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Recent light snowfall combined with elevated and shifting winds have built wind slabs on a variety of aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of weak, sugary facets persists at the bottom of the snowpack at higher elevations. Steep, rocky alpine features where the snowpack transitions from thick to thin are the likely trigger points for this deep persistent slab problem. Easier-to-trigger wind slab avalanches or cornice falls could step down to this layer, resulting in very large and destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 11th, 2020 5:00PM
