Avalanche Forecast
Issued: Feb 12th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Cornices and Wind Slabs.
TRettie,
Avalanche Canada
Use extra caution at treeline where triggering a persistent slab avalanche is most likely. Avoid slopes with large cornices above.
Summary
Confidence
Moderate -
Weather Forecast
Saturday night: no new snow expected. Light to moderate northwest winds and a low of -11 at 1600m.Â
Sunday: mostly Sunny with light northwest winds. Freezing level rising to 1800m with the possibility of a temperature inversion.
Monday: light precipitation bringing around 5cm of snow. Moderate southwest winds and a high of -2 at 1600m.
Tuesday: light flurries bringing trace amounts of snow. Light northwest winds and a high of -3 at 1600m.
Avalanche Summary
On Thursday a snow biker triggered a size 1.5 persistent slab avalanche on a south aspect at treeline. This avalanche ran on the late January layer. See the MIN report for more details.
On Wednesday a size two natural wind slab avalanche was observed in steep alpine terrain on a east aspect.
On Monday explosives triggered numerous cornices, with some subsequently triggering slabs on the slope below. Explosives also triggered a size 3 on the early December crust, this was a reloaded bed surface at 1900m that had previously avalanched.
Snowpack Summary
A new melt-freeze crust is expected on solar aspects into the alpine and on all aspects below treeline. This crust will likely break down and become moist as the freezing level rises and the sun comes out. Previous strong wind from the southwest through northwest have formed wind slabs at higher elevations and over hanging cornices on some ridge features.
The January 30 interface is now typically down 15-40 cm and consists of a melt-freeze crust at lower elevations and on solar aspects extending into the alpine and surface hoar in sheltered areas at and below treeline.Â
The widespread January 18 rain crust is now around 40-100cm deep with weak faceted snow above. It is most prominent in the Lizard range. In heavily wind scoured areas at and above treeline this crust can be found on the surface.Â
The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous large avalanches in January but is now considered dormant. See this forecaster blog on how to manage this layer as it may come into play again later this season.Â
Terrain and Travel
- Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Cornices become weak with daytime heating or solar exposure.
- Be careful as you transition into wind affected terrain.
Problems
Persistent Slabs
Two buried weak layers remain a concern. The late-January crust/surface hoar is down 15-40 cm and the mid-January crust/facets is down 50-70 cm. The likelihood of triggering these layers could increase as the freezing levels rise. Ongoing mild temperatures could promote slab formation and increase the potential for propagation.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Large cornices are reported with the ongoing strong wind over the past week. A cornice failure has the potential to trigger a slab avalanche on the slope below.
Aspects: North, North East, East, South East, South.
Elevations: Alpine.
Likelihood
Expected Size
Wind Slabs
Recent strong winds from the SW through NW have formed wind slabs in exposed terrain at higher elevations.
Aspects: North, North East, East, South East, South, South West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 13th, 2022 4:00PM
