Avalanche Forecast
Issued: Mar 23rd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
jpercival,
Avalanche Canada
Watch for new snow and southwest winds building fresh thin wind slabs that may be reactive to skier traffic in north and east facing terrain through the day.
Summary
Confidence
Moderate
Avalanche Summary
No new avalanches of note were reported in the region this week.
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.
On Sunday, a suspected skier triggered avalanche was reported. This was a size 1 storm slab avalanche that likely occurred on Saturday.
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
Warm temperatures and strong winds have redistributed 50 cm of storm snow creating hard wind affected surfaces in alpine and exposed treeline terrain. This overlies previously wind affected snow (sastrugi) in exposed areas and faceted snow in sheltered features.
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
Thursday Night
Cloudy with light flurries, 1 to 5 cm accumulation. Strong southwest ridgetop winds easing to moderate . Alpine temperature low -8°C. Freezing levels valley bottom.
Friday
Cloudy with some afternoon clearing, isolated light flurries, 1 to 5 cm of accumulation. Light south ridgetop winds. Alpine temperature high -5°C. Freezing levels rising to 500 m.
Saturday
Cloudy with afternoon clearing, isolated very light flurries, trace to 1 cm of accumulation. Light south ridgetop winds. Alpine temperature high -6°C. Freezing levels rising to 300 m.
Sunday
Cloudy with afternoon clearing, no new precipitation. Moderate becoming strong north ridgetop winds. Alpine temperature high -7°C. Freezing levels rising to 200 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
- 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
Valid until: Mar 24th, 2023 4:00PM
