Avalanche Forecast
Issued: Feb 15th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
ldreier,
Avalanche Canada
Slabs sitting on surface hoar and sugary, faceted crystals still get triggered by humans, especially at the treeline/alpine interface. Continue to use conservative decision-making! Wind slabs on multiple aspects are preserved for human triggering due to the cold temperatures.
Summary
Confidence
Weather Forecast
MONDAY NIGHT: Mostly cloudy, trace of new snow, light westerly wind, temperature low -16 C.
TUESDAY: Sunny with cloudy periods, trace of new snow, moderate west wind, temperature high -10 C.
WEDNESDAY: Mix of sun and cloud, trace of new snow, light westerly wind, temperature high -6 C.
THURSDAY: Mix of sun and cloud, trace of new snow, light westerly wind, temperature high -5 C.
Avalanche Summary
On Monday, skiers triggered a size 1 avalanche in the alpine from a short distance away. On Sunday skiers triggered avalanches up to size 2.5 on open features at the treeline/alpine interface in the Lizard Range and Tunnel Creek. These failed on the late January persistent surface hoar layer (see this MIN as an example).
Despite the lack of snow, there has been an increase in activity on the persistent weak layer. On Thursday and Friday there were human and remote triggered avalanches up to size 2 reported. Locations like Mount Fernie, 2000, Liverwurst and McDermid were a few location examples. Some avalanches were triggered from a distance away.
February has been a busy one for avalanche activity with human triggered avalanches going back well over a week that are too numerous to list. Do some research and check out the MIN reports in our region when planning your trip, you can read them here.
Snowpack Summary
Surface faceting and surface hoar growth is promoted by clear nights and frigid temperatures. Below 1600 m a hard melt-freeze crust is underneath 20-40 cm recent snow.
A persistent weak layer lurks 30-70 cm below the surface. In some places it consists of surface hoar, in other places just facets, or crust/facet combinations. This weak interface has been responsible for the majority of recent avalanches. Reports suggest the surface hoar interface at treeline is the biggest repeat offender, and things have been most reactive on northerly and easterly aspects, but don't let your guard down elsewhere.
A solid mid-pack sits above a deeply buried crust and facet layers near the bottom of the snowpack (150-200 cm deep), which is currently unreactive.
Terrain and Travel
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Persistent Slabs
Human triggering of this layer is likely. Small terrain features are producing small avalanche results, bigger features produce larger more dangerous avalanches. 40-65 cm of snow sits above a buried weak layer consisting of surface hoar, facets, and a crust (depending on elevation and aspect). The surface hoar interface is the biggest repeat offender, and things have been most reactive on northerly and easterly aspects at treeline, but don't let your guard down elsewhere! These kinds of avalanches can happen in surprisingly mellow terrain and can be triggered from a distance away.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Look out for wind slabs in unusual places. There have been some localized moderate to strong winds from variable directions during the weekend. Newer reactive wind slabs will be slow to bond where they sit over cold sugary facets. There is also potential for wind slabs to step down to the late January persistent weak layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 16th, 2021 4:00PM
