Avalanche Forecast
Issued: Apr 12th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Cornices, Loose Wet and Wind Slabs.
shorton,
Avalanche Canada
Danger will elevate throughout the day as slopes warm up. Plan your day around avoiding cornices and sun-exposed slopes. Read more in this Forecasters' Blog.
Summary
Confidence
Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.
Weather Forecast
MONDAY NIGHT: Mostly cloudy skies, 30 km/h southwest wind, freezing level around 1200 m with treeline temperatures around -2 C.
TUESDAY: Mix of sun and cloud, 20 km/h southwest wind, freezing level climbs from 1200 to 1900 m throughout the day, treeline temperatures climb to +1 C.
WEDNESDAY: Sunny, light wind, freezing level climbs from 2000 to 2700 m throughout the day, treeline temperatures climb to +5 C.
THURSDAY: Sunny, light wind, freezing level steady around 2800 m, treeline temperatures around +5 C.
Avalanche Summary
Warm sunny weather this week will likely cause wet loose avalanches on sun-exposed slopes and large cornice falls. After several days of warm weather natural slab avalanches will become a concern.
There were many small (size 1) wet loose avalanches on south-facing slopes at all elevations on Sunday and a few size 2 cornice failures on north and east facing slopes. On Saturday there were a few naturally triggered wind slab avalanches (up to size 2) on northeasterly aspects in the alpine.
Snowpack Summary
Sunny skies and rising freezing levels will result in melting surfaces on solar aspects and lower elevations. 5-20 cm of snow is quickly settling and strengthening, although some wind slabs could linger at upper elevations. The recent snow has covered a variety of snow surfaces, including wind affected snow, crusts on solar aspects and at lower elevations, and soft snow on sheltered slopes at upper elevations.
The lower snowpack is reported as well settled and strong in most areas. However, weak facets exist at the base of the snowpack in the more shallow snowpack zones across the region. Where it exists, this layer has the potential to be triggered on steep, rocky slopes with a shallow or thin to thick snowpack; especially with large loads such as a cornice fall.
Cornices are large, looming, and capable of triggering large avalanches when they fail.
Terrain and Travel
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Avoid exposure to slopes that have cornices overhead.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
Problems
Cornices
Cornices are large and looming along many ridgelines and have likely grown with the recent wind. Strong solar radiation and warming are common triggers for cornice failures which could trigger avalanches on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
Small wet loose avalanches may start to run naturally on steep solar aspects when the sun comes out.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Lingering wind slabs formed by 10-20 cm of recent snow and previously strong winds from shifting directions may remain reactive on lee features in the alpine.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 13th, 2021 4:00PM
