Avalanche Forecast
Issued: Dec 25th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
Mark Herbison,
It's a tricky snowpack in many parts of the forecast region with a lot of variability with recent winds, snowfall and multiple weak layers.
There is a Special Avalanche Warning in effect. Click Here to access.
Happy Holidays!
Summary
Weather Forecast
Saturday will be cloudy with snow accumulations between 2-10cm over the region. The temperature inversion will dissipate as temps gradually get cooler over the next few days, ranging from -8 to -14. Winds will taper off Friday evening and remain light through the weekend. Cool temps, light winds and no snow in the 5 day forecast.
Snowpack Summary
Recent 25-45km/hr SW-W winds have blown the 30-60cm of snow from the past week into wind slabs at higher elevations. The Dec 13 and Dec 7 sun crust/surface hoar/facet layers are down ~ 50cm and ~80 cm respectively. The decomposing Nov crust/facets sits at the bottom of the snowpack. Height of snow at tree line is 120-170cm.
Avalanche Summary
Avalanche control this week produced mixed results, from no result to size 3.0. Control on Mt. Dennis on Thursday produced numerous size 2.0 avalanches, initiating in pockets of alpine wind slab and entraining additional snow in the tight gullies below, see MIN. These results are easily produced due to the steep and tight nature of the terrain.
Confidence
Problems
Wind Slabs
New wind slabs were formed from strong SW-W winds on Wednesday into Friday. These are mainly found in the alpine but have been reported at tree line as well.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
There are a variety of weaker layers down ~50-80cm depending on the area. These are the Dec 7 and 13th layers of facets, suncrust, and isolated surface hoar. Their reactivity is a bit sporadic but treeline seems to be the biggest culprit.
- Dig down to find and test weak layers before committing to a line.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 26th, 2020 4:00PM
