Avalanche Forecast
Issued: Nov 29th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
swerner,
Avalanche Canada
New snowfall amounts will vary across the region on Tuesday. If you see less than 25 cm in your local area the avalanche danger is CONSIDERABLE.
Summary
Confidence
Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.
Weather Forecast
The Interior regions will see the effects of the next atmospheric river by Tuesday. Precipitation will fall as snow at upper elevations and rain lower. Strong to extreme southwest wind will exist and freezing levels will be on the rise from 1400 m to 2500 m Tuesday night through Wednesday.
Monday Night: Periods of snow 5-10 cm. Alpine temperature -4 and freezing level 1500 m. Strong southwest wind.
Tuesday: Snow 10-20 cm at upper elevations. Alpine temperatures near -2 and freezing level 1800 m. Strong to extreme forecast southwest wind.
Wednesday: Heavy snow at upper elevations 20-30 cm. Alpine temperatures near -4 and will slowly climb to 0 degrees in some areas. Freezing level rising to 2300 m. Strong southwest wind.
Thursday: Snow continues 5-10 cm. Alpine temperatures near -4 and freezing level dropping to 1400 m. Strong southwest ridgetop wind.Â
Avalanche Summary
Natural avalanche activity will be on the rise Tuesday with new snow, rain, wind, and rising freezing levels. Pay attention to your localized weather observations as the snow amounts differ across the region. Generally, if you see more than 25 cm and wind consider the hazard to be HIGH. It looks like the Dogtooth Range may see the least amount of snow which may keep the danger at CONSIDERABLE.
On Sunday numerous natural avalanches up to size 2 were observed in the Toby creek drainage. These avalanches ran on a surface hoar layer believed to be widespread in this area above 1600m. Several storm slab avalanches up to size 1.5 were observed in the Northern part of the range.
Snowpack Summary
New storm slabs will build with the incoming snow and bury recent wind slabs found at the treeline and the alpine. A surface hoar layer has been observed down 30 to 40cm in the Toby Creek drainage. The mid-November rain crust is throughout the region and down 30 to 60cm. It generally exists below 1900 m. Several early season crusts exist throughout the lower pack and a late October facet/crust layer sits at the bottom of the snowpack above 1900 m. Warm moist snow exists at lower elevations.
Average snowpack depth at treeline is 100cm to 180cm, with the deepest snowpack found around the Bugaboos.
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Make conservative terrain choices and avoid overhead hazard.
Problems
Storm Slabs
Storm slabs will build through the day with new snow and wind. Natural avalanche activity is likely and storm slabs could run to lower below treeline elevations, especially in parts of the region that receive heavy snowfall.
Loose dry avalanches may be seen from steep terrain features and can catch you by surprise.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of Facets at the base of the snowpack from late October has been observed. We need more information on the distribution of this layer but we suspect it only exists at high treeline elevations and into the alpine.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Nov 30th, 2021 4:00PM
