Avalanche Forecast
Issued: Dec 19th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Dry and Deep Persistent Slabs.
mark herbison,
Parks Canada
High snowfall amounts and strong winds will elevate the avalanche hazard for the next few days. Avalanches have potential to run full path down to valley bottom, especially in gully features.
Avoid overhead hazard and avalanche terrain.
Summary
Weather Forecast
The infamous 'atmospheric river' (I wonder who coined that term??) is flowing through our region for the next two days. Forecasts along the Divide predict snow accumulation up to 25cm on Friday, 25+cm on Saturday and another 10cm by Sunday morning. Temperatures will rise as the freezing level reaches 1600m. Winds will be strong from the SW.
Snowpack Summary
Recent strong winds have formed wind slabs in the alpine and exposed tree line areas. The snowpack structure is generally weak, consisting of facets and depth hoar and will be stressed by the incoming storm snow. The Nov crust is present up to 2500m and ~30 cm up from ground. Snowpack depths at treeline range from 80-160 cm.
Avalanche Summary
No new natural avalanche activity in the past few days, though there have been reports of skier triggered wind slabs up to sz 1.5.
Explosive avalanche control at local ski areas have produced sz 1.0 windslabs in steep, wind loaded areas.
Confidence
Problems
Wind Slabs
As the storm intensifies on Friday, expect the incoming snow and strong South West winds to build touchy wind slabs on lee aspects in the alpine and exposed areas at tree line.
- Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
As the snow accumulates, expect sluffing and point releases from steep, rocky terrain and gullies.
- Choose ice climbs that are not exposed to avalanches from above.
- Be careful of loose dry power sluffing in steep terrain..
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The incoming storm snow will stress the weak, faceted snowpack. Lots of uncertainty surrounds this layer, but if triggered it could result in a large avalanche.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 20th, 2019 4:00PM
