Avalanche Forecast
Issued: Mar 27th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Persistent Slabs and Wind Slabs.
zryan,
Avalanche Canada
High overnight freezing levels and rain are expected to make the snowpack weak at lower elevations, with new wind slabs potentially forming up high.
Watch for changing conditions throughout the day and as you move through elevation bands.
Summary
Confidence
Moderate - Uncertainty is due to difficult to forecast freezing levels.
Weather Forecast
SUNDAY NIGHT: Cloudy with snow/rain, 10 cm of accumulation above the rain-snow line. Alpine temperature around -1 C. Ridge winds 25-40km/h southwest. Freezing level 1800m.
MONDAY: Cloudy with flurries, up to 5 cm of accumulation above the rain-snow line. Alpine temperature around -3 C. Ridge winds 15-30 km/h northwest. Freezing level 1700 m.
TUESDAY: Mainly sunny. Alpine high of 3 C. Ridge winds 15-40 km/h southwest. Freezing level rising to 2000 m.
WEDNESDAY: Mainly cloudy with flurries. Alpine temperatures around -3 C. Ridge winds 15-40 km/h southwest. Freezing level rising to 1600 m.
Avalanche Summary
A skier-triggered size 2 persistent slab avalanche was reported on Saturday. This avalanche was remote-triggered, meaning the skier was a distance away from where the avalanche failed. It was in a wind-loaded area at treeline on a southeast aspect.Â
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.Â
Looking forward, riders may be able to trigger wind slabs in lee terrain features in the alpine and treeline and wet loose avalanches in steep terrain at lower elevations. It also may be possible to trigger the weak layer described in the Snowpack Summary, where it still exists.
Snowpack Summary
Up to 20 cm of recent snowfall tapers rapidly with elevation. Southwest wind have formed pockets of windslab in the alpine and exposed treeline. A refrozen crust can be found below the new snow on all aspects as high as 2300 m. This crust is expected to break down throughout the day with rain and warm temperatures. Below the crust, the top 10-30 cm of the snowpack is moist. At very low elevations, the snowpack may become wet and isothermal.
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.Â
The remainder of the snowpack is well-bonded.
Terrain and Travel
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Wind slabs may be poorly bonded to the underlying crust.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Loose Wet
Rain at lower elevations may cause the surface crust to break down. The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
Aspects: All aspects.
Elevations: Treeline, Below 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
Wind Slabs
Wind slabs may be found in steep, lee terrain features in the alpine and exposed treeline. These wind slabs will be most reactive where they overlie a slick crust.
Warm temperatures may cause cornices to become weak. Cornice failures are dangerous on their own, but also have the potential to trigger larger avalanches on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 28th, 2022 4:00PM
