Avalanche Forecast
Issued: Feb 8th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
MBender,
Avalanche Canada
Wind slabs at upper elevations are the main concern. The forecast calls for a stable weather pattern in the next few days.
Summary
Confidence
Weather Forecast
Saturday Night: Cloudy with clear periods. Light northwest wind. Alpine high temperatures around -10.
Sunday: Mainly cloudy with sunny breaks and isolated flurries. Light to moderate west wind. Alpine high temperatures around -8.
Monday: A mix of sun and cloud. Light west winds. Alpine high temperatures around -6.
Tuesday: Scattered flurries. Light to moderate southwest winds. Alpine high temperatures around -5.
Avalanche Summary
Reports of new avalanche activity Wednesday through Friday were limited to small (size 1-1.5) skier or rider triggered wind slabs along steep ridgetop features.
Reports from Wednesday included three very large (size 3) persistent slab avalanches in the southeastern part of the region, not far from Allan Creek. These avalanches failed naturally on the 150 cm-deep late December surface hoar described in our snowpack summary. They occurred on north and east aspects at around 2300 metres.
Snowpack Summary
20-60 cm of snow from the last week overlies previously wind-affected snow at higher elevations, with diminished depths of about 20-30 cm above a widespread melt-freeze or rain crust up to about 1700 metres. This recent snow has shown variable reactivity, with reports showing a mix of soft wind slabs around treeline, sluffing of low density snow in steep terrain, and poor bonding with the buried crust where it exists.
The mid and lower snowpack are generally well settled, however an aging weak layer of surface hoar from late December, currently buried 70 to 150 cm deep, has shown surprisingly long-lived instability on slopes between 1700-2400 m (above the crust elevation and below the most wind-affected elevations), warranting increased caution around steeper slopes in this elevation band, particularly in the southern half of the region.
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Be alert to conditions that change with elevation and sun exposure.
Problems
Wind Slabs
Recent snowfall combined with elevated and shifting winds will build new wind slabs. Be mindful of areas where wind slab and cornice distribution overlap.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of buried surface hoar may persist deeper in the snowpack in the south of the region. Easier-to-trigger wind slab avalanches or cornice falls could potentially step down to this persistent slab problem resulting in a very large and destructive avalanches.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Feb 9th, 2020 5:00PM
