Avalanche Forecast
Regions: South Rockies.
On the BC side where surface hoar exists at treeline, conservative decision making will be essential. Otherwise, look out for windslabs in unusual places due to variable wind directions and read our latest forecaster blog "Managing Moderate".
Confidence
Moderate -
Weather Forecast
SUNDAY NIGHT - A few clouds / light north west wind / low of -21
MONDAY - Overcast, trace of new snow / light south west wind / -9
TUESDAY - Partly cloudy, light westerly wind, high of -7
WEDNESDAY - Decreasing cloud, light westerly wind, high of -6
Avalanche Summary
A skier accidentally triggered a size 1.5 wind slab in a reverse loaded feature on the Alberta side of the region on Saturday.
There are recent reports in the South Rockies region of human triggered avalanches on a persistent weak layer of feathery surface hoar. One of the groups made a MIN report for us, check it out.Â
Skiers triggered a large (size 2.5) avalanche on a south facing slope in K-Country (forecast region to the north of us) on Thursday. Facets over an old sun crust may have played a role. You can read the MIN report here.
Ski cuts have been producing small avalanches avalanche in reverse loaded terrain.Â
Snowpack Summary
Variable winds have redistributed loose snow developing wind slabs in lee features, especially in the alpine and open areas at treeline. In sheltered zones the surface snow is becoming faceted and sugary and sluffing should be expected in steep terrain.
A persistent weak layer lurks 40-65 cm below the surface. In some places it consists of surface hoar, in other places just facets, or crust/facet combinations. Reports suggest the surface hoar interface at treeline in the Elk Valley is the biggest repeat offender, and things have been most reactive on northerly and easterly aspects, but don't let your guard down elsewhere.Â
A solid mid-pack sits above deeply buried decomposing crust and facet layers near the bottom of the snowpack. Though unreactive under the current conditions, steep rocky slopes and shallow snowpacks should still be approached with caution.
Terrain and Travel
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- 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.
- If triggered, loose dry avalanches may step down to deeper layers resulting in large avalanches.
Avalanche Problems
Persistent Slabs
40-65 cm snow sits above a buried weak layer of surface hoar, facets, and a crust (depending on elevation and aspect). Reports suggest the surface hoar interface at treeline in the Elk Valley is the biggest repeat offender, and things have been most reactive on northerly and easterly aspects, but don't let your guard down elsewhere.
Small terrain features are producing small avalanche results, bigger features could produce larger more dangerous avalanches. These kinds of avalanches can happen in surprisingly mellow terrain and be triggered from a distance away.
Aspects: All aspects.
Elevations: Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Wind Slabs
Look out for wind slabs in unusual places. There have been some localized moderate to strong winds from variable directions. 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 layer in isolated areas .
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2