Avalanche Forecast
Issued: Dec 7th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Loose Wet.
dsaly,
Avalanche Canada
More snow, wind, and rain to load an already stressed snowpack. Stick to simple terrain and keep your distance from overhead hazards.
Summary
Confidence
Moderate - Uncertainty is due to rapidly fluctuating freezing levels.
Weather Forecast
MONDAY NIGHT: Wet snow, 25-45 cm / Strong, southwest ridgetop wind / alpine low temperature -1 / Freezing level spiking above 2000 m
TUESDAY: Snow and flurries, 10-20 cm / Moderate, gusty southwest ridgetop wind / alpine high temperature -2 / Freezing level 1600 m
WEDNESDAY: Isolated flurries, 5 cm / Light, west ridgetop wind / alpine high temperature -3 / Freezing level 1000 m
THURSDAY: Cloudy with isolated flurries / Light, southeast ridgetop wind / alpine high temperature -6 / Freezing level 800 m
Avalanche Summary
Other than of a few small loose-wet avalanches from steep terrain, there have been no avalanche observations since last Wednesday (Nov 2) when natural widespread wet loose avalanche cycle up to size 3 was triggered by warming.
Have you been out and about in the mountains? If so please submit to the Mountain Information Network (MIN). It doesn't have to be technical it can be as simple as a photo. Photos are especially helpful! Sending out a big thank you to the already submitted MIN's this season. Thanks everyone!
Snowpack Summary
Rain and warm temperatures produced moist snow to 1700 m. Above the rain/snow line, 10-15 cm new snow has accumulated through Monday.
Prior to the storm, a melt-freeze crust covered most surfaces. A variety of wind affected surfaces covered more northerly, alpine terrain. Large surface hoar growth was observed around treeline, but was likely destroyed by this wet and warm storm. A saturated snowpack is found at lower elevations from rain.
Snowpack depths vary with elevation and exposure to sun and wind, before this storm average snowpack depths were 80-100 cm around treeline to over 150 cm in the alpine.
The mid to lower snowpack contains a series of crusts, the most notable of which is also the deepest, sitting just above the ground at elevations above 1500 m. This crust may have a thin overlying layer of weak faceted grains and/or surface hoar crystals, especially in sheltered areas around treeline. Loading and observations from this storm may provide insight on if these layers will be a concern going forward.Â
Terrain and Travel
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
Problems
Storm Slabs
Continuing snow and wind will build storm slabs at upper treeline and alpine elevations (anywhere snowfall accumulates instead of rain). Avalanche hazard may peak overnight Monday/early Tuesday as freezing levels spike. The most reactive slabs will be in wind-loaded areas or around ridges and convex rolls. Be wary of cornices, they may grow quickly under the current conditions.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
At elevations that receive rain (instead of snow) and above 0 temperatures, a wet loose hazard will persist as long as the snowpack is moist or wet.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 8th, 2020 4:00PM
