Avalanche Forecast
Issued: Mar 19th, 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
Warm sunny weather continues. Use increased caution when slopes and cornices warm up throughout the day. Deeper weak layers may still persist. Make observations and assess conditions continually as you travel.
Summary
Confidence
Moderate - Uncertainty is due to limitations in the field data.
Weather Forecast
Thursday night: Decreasing cloud, light northwest wind, alpine temperature -11 C, freezing level valley bottom.
Friday: Mostly clear, light northwest wind, alpine temperature -5 C, freezing level 1700 m.
Saturday: Increasing cloud, light southwest wind, alpine temperature -7 C, freezing level 1600 m.
Sunday: Increasing cloud, light southwest wind, alpine temperature -7 C, freezing level 1600 m.
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 in the alpine. 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, was 40-80 cm deep and ran on depth hoar near the base of the snowpack.
The number of data sources for the region is diminishing as professional operations close. If you're spending time in the mountains, consider sharing your observations via the Mountain Information Network. Heightened diligence and conservative risk management is recommended at this time.
Snowpack Summary
On Wednesday, temperatures reached 0 C up to 2000 m with strong solar radiation. You can expect to find either moist surface snow or crust on sun-exposed slopes.Â
New snow from last week may sit on a weak surface hoar layer and a sun crust on steep solar aspects. Moderate to strong northeast and east wind redistributed snow and formed wind slabs that may remain possible to trigger in isolated areas.Â
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. There is a low likelihood of triggering an avalanche on this layer, but the consequences of doing so would be high. Read more about surface hoar on our forecaster blog.
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. Additionally a weak layer of surface hoar sits 50-100 cm deep, within the range for human-triggering.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 20th, 2020 5:00PM
