Avalanche Forecast
Issued: Mar 11th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
cgarritty,
Avalanche Canada
Analyze the snow surface for patterns of wind redistribution to navigate around wind slab problems at higher elevations, but approach steep, sheltered openings with caution. A potentially touchy layer of surface hoar was buried with the last snowfall.
Summary
Confidence
Weather Forecast
Wednesday night: Clear periods. Moderate northwest winds.
Thursday: Mainly sunny with cloud increasing in the afternoon. Light northwest winds. Alpine high temperatures around -12.
Friday: Mainly cloudy. Light to moderate northeast winds. Alpine high temperatures around -13.
Saturday: Becoming sunny. Light to moderate northeast winds easing over the day. Alpine high temperatures around -17.
Avalanche Summary
Reports from the Whistler area on Wednesday showed numerous small (up to size 1.5) storm slabs releasing with ski cutting. Here, 10 cm of new snow with strong to extreme winds resulted in slab depths of up to 80 cm.
Similar reactivity with greater slab depth and destructive potential was likely in southern parts of the region where up to 30 cm of new snow fell. These recent wind slab formations may remain reactive to human triggering on Friday.
Snowpack Summary
10-30 cm of new snow fell over the region during Tuesday's storm, with the greatest amounts found at higher elevations and toward the south of the region. Strong to extreme winds were a notable feature of the storm. The new snow - wind-affected at higher elevations - has buried variable surfaces that include surface hoar in sheltered areas, sun crusts on southerly slopes, and yet more wind-affected surfaces in exposed areas.
A weak layer of surface hoar crystals and/or faceted grains may be found around 100 cm deep on northerly aspects at treeline and lower alpine elevations. For some of the region, the layer may have been destroyed by strong wind immediately before burial on February 22nd, but it may still exist in sheltered terrain features in parts of the region. In these areas, larger avalanches composed of new snow may cause isolated step down avalanche activity at this layer.
Weak faceted snow and melt-freeze crusts exist near the base of the snowpack in some of the region, particularly the eastern and northern parts. This layer is considered dormant, as it hasn't produced an avalanche since February 20th. This layer may require a very large load, such as a cornice fall, or rapid weather changes to reactivate.
Terrain and Travel
- Be carefull around freshly wind loaded features.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
Tuesday's storm brought 10-30 cm of new snow and strong to extreme winds. Expect to find new wind slabs perched in steep leeward features throughout the region, with the greatest depths and associated avalanche danger found in southern areas and high elevations. Keep your guard up in steep, sheltered lower elevations with more than 15 cm of new snow - it may overlie a touchy layer of surface hoar.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 12th, 2020 5:00PM
