Avalanche Forecast
Issued: Mar 25th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Wind slabs may be reactive to human triggering at upper elevations. Use caution in lee and cross-loaded terrain near ridge crests.
Summary
Confidence
High - The snowpack structure is generally well understood.
Weather Forecast
FRIDAY NIGHT: Cloudy with light snowfall, up to 5 cm accumulation. 15 to 35 km/h southwest wind, alpine temperature -6 C.
SATURDAY: Cloudy with light snowfall, up to 5 cm of accumulation, 15-30 km/h southwest winds, alpine temperature rising to -3 C. Freezing level reaching 1700 m.
SUNDAY: Cloudy with precipitation, 5-10 cm of new snow accumulation at higher elevations. 20-40 km/h southwest winds, alpine temperature rising to -3 C. Freezing level reaching 2200 m.Â
MONDAY: Cloudy with snowfall, 5 cm accumulation. 15-30 km/h northwest winds, alpine temperature rising to -3 C. Freezing level reaching 2000 m.
Avalanche Summary
Two persistent slab avalanches were reported near Blue River on Thursday, both on south-facing alpine slopes. One was a very large (size 3.5) natural avalanche and the other was a small (size 1.5) slab remotely triggered by riders.
Widespread loose wet and wet slab avalanche activity occurred during the warm-up on Wednesday.Â
Looking forward, riders may be able to trigger wind slabs in lee terrain features in steep alpine terrain. It also may be possible to trigger the weak layer described in the Snowpack Summary, where it still exists.
Snowpack Summary
Above 2000 m, 10 to 20 cm of recent snow may have formed wind slabs in lee terrain features from southwest wind. Below 2000 m, up to 10cm of new snow overlies a melt-freeze crust with moist snow below.
A weak layer that is isolated in nature may be found around 40 to 60 cm deep, which has been most prominent in the south of the region (e.g., access points between Clearwater and Valemount). The layer consists of surface hoar crystals in treeline terrain on northerly aspects or weak faceted grains above a hard melt-freeze crust on sun-exposed slopes (i.e., east, south, west). The last avalanche observation on this layer was March 23 near Blue River. The recent warm spell has likely made this layer inactive, but it should still be treated as suspect if you find it in your riding area.
The remainder of the snowpack is well-bonded.
Terrain and Travel
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Carefully evaluate steep lines for wind slabs.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Wind slabs may be found in steep, lee terrain features in the alpine and exposed treeline.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer may be found around 40 to 60 cm deep, particularly in the south of the region (e.g., Wells Gray, Blue River, Valemount). The layer consists of weak faceted grains above a hard melt-freeze crust on sun-exposed slopes and surface hoar in shaded areas sheltered from the wind. This layer is becoming harder to trigger, but a resulting avalanche would be large and destructive.
Most recent activity has been on south aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 26th, 2022 4:00PM
