Avalanche Forecast
Issued: Feb 22nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
mconlan,
Avalanche Canada
Storm slabs will build over the day with snowfall and strong wind. Use added caution on steep slopes in open trees, as a slab may rest on surface hoar, particularly in the east of the region. Conservative decision-making is recommended.
Summary
Confidence
Moderate - Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.
Weather Forecast
SATURDAY NIGHT: Cloudy with light snowfall, accumulation 1 to 3 cm, light to moderate southwest wind, alpine temperature -6 C.
SUNDAY: Cloudy with snowfall, accumulation 10 to 20 cm, moderate to strong southwest wind, alpine temperature -5 C, freezing level 1200 m.
MONDAY: Mix of sun and cloud with isolated flurries, accumulation 1 to 3 cm, light to moderate northwest wind, alpine temperature -7 C, freezing level 1000 m.
TUESDAY: Partly cloudy, light northwest wind, alpine temperature -7 C, freezing level 800 m.
Avalanche Summary
No new avalanches were observed on Friday. Avalanche activity may increase on Sunday during the stormy conditions.
Snowpack Summary
Storm slabs are expected to build over Sunday with around 10 to 20 cm of snow and strong southwest wind. The snow will accumulate onto a widespread layer of feathery surface hoar crystals or a melt-freeze crust on southerly aspects. The surface hoar was reported as being around 6 to 12 mm in size before being buried.
A 20 to 30 cm thick slab has been reactive to human traffic since last weekend, where the snow overlies another weak layer of surface hoar. The slab has been most reactive in open trees in the eastern part of the region.
The remainder of the snowpack is well-settled.
Terrain and Travel
- Watch for fresh storm slabs building throughout the day.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
Problems
Storm Slabs
Storm slabs are expected to build over the day as the storm passes. Snowfall rates could reach 3 to 5 cm per hour and winds are expected to be strong from the southwest. The snow will fall onto a weak layer of surface hoar and may not bond to it.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A 20 to 30 cm slab has been reactive to riders over the past week. The slab has been touchiest in open trees in the east of the region, where the slab rests on a layer of weak and feathery surface hoar crystals that was buried mid-February. The spatial distribution of the surface hoar layer is unclear and may be spottier in the west of the region.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 23rd, 2020 5:00PM
