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 and Wind Slabs.
TRettie,
Avalanche Canada
Keep an eye on the temperatures and snow surface. The potential for warm air aloft could prevent any overnight recovery from taking place. If you are not travelling on a thick crust Then it may be possible to trigger the late January layer.
Summary
Confidence
Weather Forecast
Saturday night: light west winds with a above freezing layer between 1300m and 2500m. no new snow expected.
Sunday: mix of sun and clouds with a above freezing layer between 1500m and 2500m.Light west winds.
Monday: light precipitation bringing up to 5cm of snow. Light west winds shifting to Moderate northwest. Freezing levels rising to 1300m.
Tuesday: a mix of sun and cloud with the possibility of some light flurries bringing trace amounts of snow. Freezing levels rising to 1500m. Light northwest winds.
Avalanche Summary
On Thursday two size 1 persistent slab avalanches were triggered by skiers on east aspects at treeline. In the southern part of the neighboring South Columbia region a vehicle triggered a size 3 avalanche at treeline running on the early December crust. This avalanche was on a northeast aspect and ran full path.
On Wednesday a skier triggered a size 2 persistent slab avalanche just below a ridge top at 2100m on a northeast aspect. This avalanche ran on the late January surface hoar.
On Tuesday explosives triggered persistent slab avalanches up to size 3 on northeast aspects at 2200m. These avalanches ran on the late January surface hoar and showed substantial propagation.
On Monday numerous persistent slab avalanches to size 2.5 were observed in the treeline and below. triggers included cornice falls, ski cuts and naturals. Avalanches were observed on all aspects.
Snowpack Summary
A crust has formed on all aspects and elevations except high north terrain. This crust could soften throughout the day with rising temps and sun exposure. Recent strong wind from the southwest have formed wind slabs in exposed terrain at higher elevations.
The January 30 interface is now typically down 20-40cm 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.
The mid-January interface is now down around 40-70 cm and consists of a crust, facets, and/or surface hoar.
The early-December crust/facet persistent weak layer is buried down 100-200 cm. It had been responsible for significant avalanche activity in this region during the first half of 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.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of buried weak layers.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
- Be careful as you transition into wind affected terrain.
Problems
Persistent Slabs
20-50 cm of settling snow sits over the January 30 surface hoar. This layer was responsible for numerous natural and human-triggered avalanches earlier in the week. Treat open slopes at and below treeline with extra caution where the surface hoar is most prominent.
The weak layer from mid-January down 40-70 cm remains a concern in isolated areas and avalanches may still have the potential to step-down.
The likelihood of triggering these layers could increase as the freezing levels rise and the sun comes out. Ongoing mild temperatures could promote slab formation and increase the potential for propagation.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Recent strong winds from the south have formed wind slabs in exposed terrain at higher elevations. These slabs are particularly reactive where they overlie buried surface hoar.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 13th, 2022 4:00PM
