Avalanche Forecast
Issued: Apr 11th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Cornices and Loose Dry.
zryan,
Avalanche Canada
Don't let good weather lure you into dangerous terrain.
Dry storm snow may be seeing its first test of strong sun, and avalanche danger could increase rapidly.
Summary
Confidence
Avalanche Summary
A natural avalanche cycle occurred over the weekend. Storm and wind slabs up to size 3 were observed at treeline and above. Cornice failures initiated large slabs on the slope below. Check out this MCR for a report from the Pemberton Icefield.
On Monday, explosive control in the Whistler area produced numerous large (size 2-3) storm and wind slabs, predominantly from wind-loaded alpine terrain. Check out Wayne Flann's blog for photos of these avalanches.
Looking forward to Wednesday, we suspect that rider-triggerable wind slabs may still be found at treeline and above. Strong sun could rapidly increase avalanche danger. Be cautious during periods of strong solar input, especially on slopes with large cornices overhead.
Snowpack Summary
Up to 70 cm of recent storm snow was accompanied by strong to extreme southerly winds, forming wind slabs on west through east aspects at treeline and above. These winds have also scoured exposed windward slopes. A crust exists on or near the surface at lower elevations and to ridgetop on solar aspects.
A crust from early April can be found down 50 to 80 cm on all solar aspects and at treeline and below on north-facing terrain. Below this crust, the snowpack is generally well-settled.
Weather Summary
Tuesday night
Clear periods. Alpine temperatures drop to a low of -9 °C. Ridge wind light from the west. Freezing level at valley bottom.
Wednesday
Sunny with cloudy periods. Alpine temperatures reach a high of -3 °C. Ridge wind light from the north. Freezing level rises to 1600 metres.
Thursday
Mainly cloudy with scattered flurries, up to 5 cm accumulation. Alpine temperatures reach a high of -5 °C. Ridge wind 15 to 30 km/h from the southwest. Freezing level rises to 1200 metres.
Friday
A mix of sun and cloud. Alpine temperatures reach a high of -3 °C. Ridge wind 10 to 40 km/h from the southwest. Freezing level rises to 1500 metres.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be alert to conditions that change with elevation and sun exposure.
- Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Wind Slabs
30 to 70 cm od recent storm snow and southerly winds have formed wind slabs in lee and cross-loaded terrain at treeline and above.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Recent storms have formed large and fragile cornices. Be especially cautious during periods of strong sun, natural cornice failures have the potential to initiate large slab avalanches on the slopes below.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
Strong solar input may rapidly impact the surface snow, initiating dry loose avalanches from steep terrain.
Aspects: East, South East, South, South West, West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 12th, 2023 4:00PM
