Avalanche Forecast
Issued: Dec 21st, 2020 4:21PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Deep Persistent Slabs and Loose Dry.
Ian Jackson,
Avalanche control on Mt. Stephen, Mt Field and Mt. Dennis in Little Yoho. No access to these areas on Tuesday Dec. 22.
Summary
Weather Forecast
An early christmas present of 15-40 cm has started to fall as I write this bulletin. The highest amounts are on the south and east sides of the bulletin area. Mostly light S winds switching to N becoming strong at the end of the storm. Tuesday: cool with clearing skies. Wed and Thurs: sunny and cold with lows near -20 and increasing alpine winds
Snowpack Summary
30-60 cm over the last week have been blown into windslabs in the alpine and down into tree line from strong West winds. The Dec 13 and Dec 7 sun crust/surface hoar/facet layers are down ~ 35cm and ~65cm respectively. The decomposing Nov crust/facets sits at the bottom of the snowpack. Height of snow at tree line is 80-150cm.
Avalanche Summary
Minimal activity in the Lake Louise Ski Hill area but Sunshine Village ski patrol had some notable observations. A size 2.5 -3 was triggered with explosives in the "Wheelers" path above the ski out which stepped down to ground (2m in spots) and ran full path. They also reported a size 1.5 failing on surface hoar down 50 cm BTL in the Wild West area
Confidence
Intensity of incoming weather systems is uncertain
Problems
Storm Slabs
15-40 cm is expected overnight Monday. We expect this to slide easily until it has had time to settle. These storm slabs could potentially trigger the deep persistent or persistent slab problem.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The new load will likely awaken either the Nov. 5th facet/crust layer at the bottom of the snowpack or the Dec. 7th surface hoar/facet/sun crust layer ~50cm down. Stay out of avalanche terrain!
- Avoid avalanche terrain.
- Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Dry
With the incoming snow, loose dry avalanches will run in gully features and steep terrain.
- Minimize overhead exposure during periods of heavy loading from new snow, wind.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 22nd, 2020 4:00PM
