Avalanche Forecast
Issued: Mar 14th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Conservative terrain selection will be critical as riders have been surprised in recent days by large avalanches failing on a weak layer of surface hoar.
Choose low consequence features and watch for signs of instability like whumpfing, shooting cracks or recent avalanches.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast. Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
A series of frontal systems impacting the coast will bring continued snowfall throughout the week.
Monday Overnight: Overcast to obscured skies. Rain at lower elevations and snowfall above ~1500 m, trace to 10 cm of accumulation, heaviest in the Kakwa. Moderate to strong southwest winds at ridge top. Freezing level around 1700 m.
Tuesday: Mainly cloudy with continued precipitation, trace to 10 cm of new snow accumulation at higher elevations. Moderate to strong southwest winds. Freezing level around 1500 m.
Wednesday: Mix of sun and cloud with light flurries. Moderate to strong westerly winds. Freezing level around 1500 m.
Thursday: Mainly cloudy with light precipitation, 1-5 cm of new snow accumulation at higher elevations. Moderate to strong westerly winds. Freezing level around 1600 m.
Avalanche Summary
Numerous natural and sledder-triggered avalanches were reported throughout the weekend in the Pine Pass area down 25-70 cm, all failing on surface hoar. The most reactivity occurring on wind-loaded, north-east aspects. Most notably, a size 2.5 sledder-triggered avalanche occurred near Bijoux Falls. The full report can be seen here.
A few sledder-triggered avalanches up to size 2 were reported in the Renshaw area on Sunday. These storm slabs were failing on a weak layer of surface hoar down 25-40 cm.
Snowpack Summary
Last weekend's 15-30 cm of new snow and moderate southwest winds formed wind slabs in areas exposed to southwest winds in the alpine and treeline.Â
This new snow is sitting on various surfaces, including hard wind-affected snow, sun crusts on southerly slopes, and most notably large surface hoar on shady or sheltered slopes. This layer of surface hoar is expected to remain problematic in the coming days, with the most reactivity observed in the Pine Pass and Renshaw area.
The mid and lower snowpack is generally well-settled and strong in most areas, with multiple crusts throughout. No recent persistent slab avalanches have been reported on these layers.
Terrain and Travel
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
Problems
Wind Slabs
15-25 cm of recent snow and moderate southwest winds formed fresh wind slabs in lee areas in the alpine and treeline. These slabs may propagate widely where they are sitting on a weak layer of surface hoar or a sun crust.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
The most recent storm buried a weak layer of surface hoar. This layer has produced large and surprising human-triggered avalanches in the past few days and reactivity is expected to persist into the week.
The most reactivity on this layer has been seen on wind-loaded, east-facing slopes in the alpine and treeline, but caution should be taken on all aspects as this problem unfolds.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 15th, 2022 4:00PM
