Avalanche Forecast
Issued: Dec 18th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Lisa Paulson,
Parks Canada
Recent SW winds have stripped the alpine, and loaded lee features with wind slabs. Good skiing can be found in sheltered areas.
Summary
Weather Forecast
Thursday - expect light flurries, moderate SW wind, and mild temperatures in the -5 to -10 range
Friday - the next storm begins elevating the avalanche hazard as it brings warmer temps (freezing levels at 1600 m), strong SW wind, and snow (15-30 cm depending on the weather model)
Saturday - expect another 10-15 cm
Snowpack Summary
Strong winds have formed new wind slabs at alpine and tree line. The distribution of this new load is uncertain. Beneath the recent 40-60 cm of storm snow, the snowpack structure is generally weak, consisting of facets and depth hoar. 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
On Tuesday there was a Skier involvement in a size 2 windslab avalanche triggered on a convex roll at treeline (Paget Peak) and a natural size 2 windslab on a S alpine aspect of Noseum Peak. Local ski hills continue to report small wind slabs reactive to ski cuts, although slightly less reactive compared to Tuesday
Confidence
Problems
Wind Slabs
48 hrs of moderate to strong winds have formed new wind slabs at alpine and tree line elevations. The distribution of the new load is uncertain. Where it is present you can expect the new load to be reactive in the short term.
- Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
- Caution on open steep slopes at treeline that have been exposed to wind loading.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The recent snow sits over weak facet and crust layers. As time goes on the chance of triggering is becoming less likely, but there is lots of uncertainty as to where you could trigger an avalanche and what it will take to get it moving.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 19th, 2019 4:00PM
