Avalanche Forecast
Issued: Dec 1st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
wlewis,
Avalanche Canada
As avalanche hazard decreases backcountry travel may be challenging. Keep an eye out for lingering storm slabs as you move to higher elevations and into wind effected terrain.
Summary
Confidence
Weather Forecast
After a final wave of moisture Wednesday night, we move into cold and clear conditions. The next round of precipitation arrives Saturday morning.
WEDNESDAY NIGHT: Precipitation tapers off early afternoon with a trace expected overnight. Freezing levels fall to 1800m by Thursday morning. Strong westerly winds.
THURSDAY: Flurries over the day, to partly cloudy skies. Winds ease to moderate westerlies. Alpine high of -7, freezing levels at 1500m, dropping to valley bottom overnight.
FRIDAY: Clear with light northerly winds. Freezing level remains below 1000m, alpine high of -10.
SATURDAY: Light to moderate accumulations, winds ramp back up to strong southwesterlies. Freezing levels remain below 1000m.
Avalanche Summary
Several size 2 wind slab were explosively triggered in the Okanagan region on eastern aspects in lee alpine features. These were reported as sliding on a melt freeze crust, 30-50cm deep.
On Saturday November 27, a size 2 storm slab was observed near Whitewater in a steep north facing treeline feature, unknown trigger.
On Friday, an avalanche cycle size 1-2 was observed from north facing alpine start zones. A size 1.5 skier accidental storm slab was also reported on the Mountain Information Network near Nelson.
Note that there are very few field observations in the Kootenay Boundary this early in the season. Backcountry users need skills in assessing conditions and decision making. If you go out in the mountains, please share your observations and/or photos on the Mountain Information Network.
Snowpack Summary
Storm totals of up to 60mm of mixed precipitation and heavy snow over the last week have landed on an already wet upper snowpack that is rapidly settling with mild temperatures. A series of rain crusts formed over the last week exist in the upper snowpack, each separated by around 10cm of moist snow.
The mid-November crust is down 40-90cm and is up to 10cm thick. The lower snowpack is a series of crust and facet layers. At the bottom of the snowpack, up to 20 cm of faceted snow sits on the ground.
Snowpack depths at treeline range from 50-100 cm, with alpine depths exceeding 150 cm in areas. Below 1700m, snowpack depths decrease rapidly with poor coverage in many below treeline areas. The entire snowpack is saturated at lower elevations.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Be alert to conditions that change throughout the day.
Problems
Storm Slabs
Storm slabs may be found at higher elevations. Investigate the bond between the slab and the old snow surface, they may still be reactive to a human trigger.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 2nd, 2021 4:00PM
