Avalanche Forecast
Issued: Mar 25th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Loose Wet.
jpercival,
Avalanche Canada
Watch for new snow and southwest winds building fresh thin wind slabs that may be reactive to skier traffic on north and east facing terrain.
Even small wet loose avalanches have the potential to push a skier over a cliff or into a terrain trap. Be cognizant of an increase in sensitivity to triggering and size when temperatures begin to rise and direct sunshine is on steep slopes and features.
Summary
Confidence
Avalanche Summary
On Friday a few loose wet avalanches were reported on south aspects in the alpine. These avalanches occurred when the sun appeared and were large (size 2).
On Thursday a few loose dry avalanches were reported on all aspects in the alpine. These avalanches were small (size 1.5).
This past week there have been no reports of natural or human trigger avalanches.
Backcountry users may see evidence of a large avalanche cycle from the weekend as they travel through the terrain. These avalanches may have occurred during last week's storm or due to solar input and elevated freezing levels through the weekend.
If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.
Snowpack Summary
Warming daytime temperatures and strong winds have redistributed 50 cm of storm snow creating hard wind affected surfaces in alpine and exposed treeline terrain. In protected areas in the alpine up to 30 cm of relatively undisturbed snow exists. This overlies previously wind affected snow (sastrugi) in exposed areas, faceted snow in sheltered features and in some places old stiff wind slab.
Specific to Haines pass and below 1300 m the 50 cm of storm snow now has a stout and supportive melt freeze crust that has capped it. An additional 5 to 15 cm of new snow now overlies this melt freeze crust.
A buried weak layer of surface hoar can be found about 80 cm deep in Powder Valley, Tutshi, Paddy Peak and Haines pass areas, 150 to 200 cm around White Pass. This layer is most prominent on northerly slopes sheltered from the wind. On other aspects, this layer is a hard melt-freeze crust with weak facets around it. This layer has been most problematic in alpine terrain.
The remainder of the middle of the snowpack is consolidated and strong. Weak faceted grains are found near the base of the snowpack, particularly in thin snowpack areas.
Weather Summary
Saturday Night
Cloudy, isolated very light flurries, trace to 2 cm of accumulation. Light north ridgetop winds. Alpine temperature high -8°C. Freezing levels falling to valley bottom.
Sunday
Cloudy with afternoon clearing, no new precipitation. Moderate north ridgetop winds. Alpine temperature high -8°C. Freezing levels valley bottom.
Monday
Mostly clear, no new precipitation. Light west ridgetop winds. Alpine temperature high -5°C. Freezing levels rising to 500 m.
Tuesday
Mostly clear, no new precipitation. Light west ridgetop winds. Alpine temperature high -4°C. Freezing levels rising to 700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Problems
Wind Slabs
Strong southwest winds and up to 15 cm of fresh snow will create fresh wind slabs in lee north and east facing terrain. Watch for wind slabs formed by last week's storm snow and southeast winds as they may linger on north and west facing terrain features.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar and/or faceted grains around a hard crust sit in the mid snowpack. This layer is buried around 80 cm in the eastern portions of the region and up to 200 cm around White Pass and Haines Pass.
This layer has previously produced widely propagating avalanches in alpine terrain and it is capable of being remotely triggered from a distance. The most likely area for riders to trigger it is in wind-sheltered, north-facing terrain, and in rocky terrain where the snowpack is thin.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
The potential for a small wet loose to push a skier over a cliff or into a terrain trap is the main concern with this avalanche problem. Be cognizant of an increase in sensitivity to triggering and size when temperatures begin to rise and direct sunshine is on steep alpine slopes and features.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 26th, 2023 4:00PM
