Avalanche Forecast
Issued: Mar 17th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.
mconlan,
Avalanche Canada
Wind slabs may still be found and the snowpack will weaken during the heat of the day, particularly on sun-exposed slopes. This warming is capable of triggering large avalanches.
Summary
Confidence
High - Confidence is due to a stable weather pattern with little change expected.
Weather Forecast
TUESDAY NIGHT: Cloudy with isolated flurries, moderate northeast wind, alpine temperature -10 C.
WEDNESDAY: Cloudy with afternoon clearing, light to moderate northwest wind, alpine temperature -4 C, freezing level 1600 m.
THURSDAY: Cloudy, light southwest wind, alpine temperature -12 C, freezing level 600 m.
FRIDAY: Clear skies, light to moderate northwest wind, alpine temperature -5 C, freezing level 1500 m.
Avalanche Summary
Many wind slab avalanches were observed in the region over the past few days caused by the reverse loading pattern. They may have been triggered from warm air temperature and sunny skies heating them up on sun-exposed slopes.
Snowpack Summary
Sunny skies have formed a melt-freeze crust on sun-exposed slopes. Recent strong easterly wind has produced wind slabs on lee terrain features. This wind direction is atypical, so you may find wind slabs in terrain features that don't usually have them.
A layer of faceted grains overly a melt-freeze crust from early February. This layer currently sits 40 to 80 cm below the surface.Â
The base of the snowpack contains basal facets that are most prominent in shallow, rocky start zones.
Terrain and Travel
- Carefully evaluate steep lines for wind slabs.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
Problems
Wind Slabs
Wind slabs formed during a reverse loading pattern from strong easterly wind. The most suspect terrain features are steep slopes near ridges. Should a wind slab be triggered, there is a potential that it could step down to a weak layer of faceted grains above a melt-freeze crust buried 40 to 80 cm.
Aspects: East, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Modest air temperature and sunny skies combine to weaken the snow surface. As this occurs, loose wet avalanche activity may result. The highest likelihood of this occurring is during the heat of the day on sun-exposed slopes. Note that the same warming trend also weakens cornices, so best to stay well back from them on ridges and avoid travelling beneath them.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak snow at the bottom of the snowpack hasn't gone away. Evidence of deep persistent slab avalanches has been focused in the Sparwood-Elkford area over the past month. Human triggering is most likely around steep, rocky terrain features or anywhere the snowpack is thin and weak. A failing cornice could initiate a deep persistent slab when it impacts the slope below.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 18th, 2020 5:00PM
