Avalanche Forecast
Issued: Mar 21st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet and Deep Persistent Slabs.
astclair,
Avalanche Canada
Clouds may temper day-time warming. Minimize exposure to cornices and steep slopes that face the sun during the warmest part of the day. A deep weak layer remain a concern.
Summary
Confidence
High - Confidence is due to a stable weather pattern with little change expected.
Weather Forecast
Saturday night: Clear, light northwest wind, alpine temperature -12 C, freezing level valley bottom.
Sunday: Increasing cloud, light southwest wind, alpine temperature -7 C, freezing level 1600 m.
Monday: Mostly cloudy, scattered flurries with up to 5 cm of snow, light southwest wind, alpine temperature -6 C, freezing level 1500 m.Â
Tuesday: Mostly cloudy, scattered flurries with up to 5 cm of snow, light southwest wind, alpine temperature -8 C, freezing level 1200 m.Â
Avalanche Summary
Over the past several days, avalanche activity was reported as natural loose wet avalanches (size 1-2.5) running in steep, sun-exposed terrain. One large (size 2.5) cornice failed as a result of explosive mitigation.
On Monday, there was a report of a skier remotely triggering (from a distance) a large (size 2) deep persistent slab avalanche at 2600 m on a northwest aspect. The avalanche was triggered from a thin spot, released 40-80 cm deep, and ran on depth hoar near the base of the snowpack.
If you decide to travel in the backcountry, consider sharing your observations via the Mountain Information Network (MIN) to supplement our data stream as operators are shutting down. A conservative mindset and margins are recommended at this time.
Snowpack Summary
With snow on the way, Sunday's surface conditions will comprise the next interface. Recent reports indicate that conditions are highly variable with a mix of sun crusts, moist snow, hard wind slabs, and soft faceted snow. Observers have noted that surface hoar may be forming on sheltered, shady slopes. These conditions will be important to track across aspects and elevations if you're spending time in the mountains on Sunday.
Cornices are large, looming, and weakening with warm temperatures and strong solar radiation.
A weak layer of surface hoar buried February 22 may be found 50-100 cm deep. Sheltered north, northeast, and east facing slopes near treeline are the most likely locations to find this layer. Avalanche activity on this layer was last reported March 11th.Â
Deeply buried facets lurk near the bottom of the snowpack. This layer has been responsible for sporadic deep persistent slab avalanches, usually triggered from shallow, rocky start zones.
Terrain and Travel
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Make observations and assess conditions continually as you travel.
Problems
Loose Wet
Small loose dry or wet avalanches are possible in steep terrain facing the sun during the heat of the day. Cornices may also warm and weaken and could act as triggers for large slab avalanches.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak faceted snow near the base of the snowpack continues to be a concern. Treat wind-scoured, rocky, shallow terrain as suspect and avoid big alpine slopes that are threatened by cornices overhead.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 22nd, 2020 5:00PM
