Avalanche Forecast
Issued: Apr 19th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Cornices and Wind Slabs.
astclair,
Avalanche Canada
Anticipate a return to spring-time avalanche concerns with sunny weather and rising freezing levels. Stay alert to steep, sun-exposed slopes and cornices during peak daytime warming.
Summary
Confidence
Weather Forecast
Monday night: Partly cloudy, light northeast winds, alpine temperature -6 C, freezing level dropping to valley bottom.
Tuesday: Sunny, light variable winds, alpine high temperature -2 C, freezing level 2200 m.
Wednesday: Sunny, light southwest winds, alpine high temperature -2 C, freezing level 2600 m.
Thursday: Cloudy, 10-20 cm of snow, moderate northeast wind, alpine high temperature -6 C, freezing level dropping throughout the day to valley bottom.
Avalanche Summary
On Friday and Saturday during peak warming and sunny weather, there were reports of natural wet loose avalanches ranging from size 1-2.5.
Snowpack Summary
An upslope storm brought a trace to 5 cm of new snow to the region, with up to 15 cm accumulating in favored areas. Moderate northeast winds with strong ridgetop gusts have formed fresh wind slabs in exposed areas at upper elevations that may still be reactive to triggers.
Sunny weather and rising freezing levels returns, which may initiate wet loose avalanches as the snow loses cohesion. Cornices are large and looming along ridgelines. Sun and warm temperatures will increase the chances of cornice failures, which could trigger avalanches on the slopes below. Check out the Forecaster's Blog for information on how to manage these spring conditions.
The snowpack is overall strong and settled in most areas. However, steep and rocky alpine slopes with a shallow or thin to thick snowpack may still harbor deeply buried weak layers. Glide cracks releasing as full depth glide slab avalanches become more common in the spring and are extremely difficult to predict. Best practice is to avoid slopes with glide cracks.
The snow line is slowly creeping up the mountains, making some access areas snow-free.
Terrain and Travel
- Extra caution is needed around cornices under the current conditions.
- Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
Problems
Loose Wet
Expect wet loose avalanches to run naturally when steep slopes are exposed to the sun. Activity will start on east-facing slopes in the morning, south-facing slopes throughout the day, and continue on west-facing slopes into the evening.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are large and fragile. Cornice falls could trigger avalanches on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Wind Slabs
New snow totals varied across the region, with anywhere from a trace to 15 cm of accumulation. Where higher accumulations of new snow have combined with moderate northeast winds, there may be reactive wind slabs in lee terrain features.
Aspects: North, East, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 20th, 2021 4:00PM
