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Avalanche Forecast

Archived

Feb 14th, 2021–Feb 15th, 2021

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

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. 

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. 

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. 

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.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.