Avalanche Forecast
Issued: Feb 26th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
swerner,
Avalanche Canada
New storm and wind slabs will start to build Saturday with the bulk of the storm hitting the region Sunday. If more than 25 cm of snow falls in your local riding area the avalanche hazard may be HIGH by Saturday afternoon.
Summary
Confidence
Weather Forecast
Yet another approaching Pacific frontal system will unleash Saturday through Monday. This will bring strong to extreme wind, rising freezing levels, and a bunch of precipitation.
Saturday: Snow starting in the morning and accumulations of 10-20 cm by the afternoon. Ridgetop wind strong from the southwest and alpine temperatures near -1. Freezing levels rising 700-900 m.
Sunday: Heavy snow expected 25-40 cm. Ridgetop wind strong to extreme. Freezing levels 1000-1200 m.
Monday: Mix of sun and cloud with some flurries. Ridgetop wind light from the southwest and alpine temperatures near -5. Freezing levels falling to 500 m.
Avalanche Summary
On Friday, numerous avalanches up to size 3 were triggered with the use of explosives. Many being size 1-2 storm slabs, however; one reported was a size 3 with the suspect failure plane being the mid-February facet interface described in the snowpack summary. A widespread natural avalanche cycle occurred on Thursday and overnight into Friday up to size 3. Additionally, This MIN from earlier this week shows excellent photos of slab avalanches around treeline elevations, potentially releasing on the surface hoar.
With another storm system on the horizon, I expect a widespread direct action avalanche cycle this weekend, especially on Sunday.
It's a good time to stay very conservative, stick to simple terrain, and be aware of overhead hazards like large avalanches and cornices.
Snowpack Summary
Storm after storm, after storm! Another storm yet to arrive…
30-60 cm of new storm snow fell by Friday morning. This came with strong southwest to northwest wind building fresh wind slabs and storm slabs at upper elevations. Below 800 m mixed precipitation of snow and rain likely fell leaving moist snow surfaces on a snowpack that was recently wet.
This now brings 80-200 cm over the plethora of old snow surfaces buried mid-February including hard wind-packed snow, feathery surface hoar crystals especially in areas sheltered from the wind, sugary faceted snow that developed during the cold snap, and a hard melt-freeze crust below treeline. Another storm and some time will tell if these old interfaces develop into a greater concern.
The mid-pack has been reported as being well-settled. There are presently no deeper concerns.
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Keep in mind that human triggering potential persists as natural avalanching tapers off.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Avoid exposure to slopes that have cornices overhead.
- Choose conservative terrain and watch for clues of instability.
Problems
Storm Slabs
40-60 cm of new snow fell by Friday morning, forming new storm slabs. This brings 80 to 200 cm of snow above a mixed bag of old snow surfaces buried mid-February. In places where a weak bond exists, deeper and bigger slab avalanches may occur. The wind is forecast to howl from the northwest to southwest, so wind slabs will rapidly build at treeline and alpine elevations too. All of this stacks up to another natural avalanche cycle, especially on Sunday. Once the natural activity tapers you can expect human triggering to be likely.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 27th, 2021 4:00PM
