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. Stay tuned in terms of the forecast for the incoming storm.
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 (up to 30 cm depending on the weather model)
Saturday - expect another15 cm
Snowpack Summary
Strong winds have formed new wind slabs at alpine and tree line. In thin snowpack areas (Mt. Dennis), the snowpack consists of recent storm snow over a weak base of facets and depth hoar. In thicker areas (140 cm +) the snowpack is more settled and less faceted. The Nov Crust is present upto 2500 m and ~30 cm up from ground.
Avalanche Summary
No new reports in the Little Yoho region. In BYK region, On Tues 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. Ski areas report ski cutting windslabs again today, but less sensitive.
Confidence
Problems
Wind Slabs
Strong wind values Tuesday have created thin wind slabs predominantly on East aspects directly below ridge top. Expect the new load to be reactive to light loads for the near future.
- Caution on open steep slopes at treeline that have been exposed to wind loading.
- Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
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
