Avalanche Forecast
Issued: Dec 7th, 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.
ghelgeson,
Avalanche Canada
We're flying blind with no recent observations, but 15 to 20 cm of storm snow has likely been formed into fresh slabs, especially in north facing terrain. Best bet is to craft conservative travel plans while watching for clues of instability. And then submit to the MIN :) Thx!
Summary
Confidence
Weather Forecast
The storm is expected to leave us with a few more centimetres of snow Tuesday night.
TUESDAY NIGHT: 2 to 10 cm of snow overnight with strong southwest wind at ridge top, temperature steady at -10 C.
WEDNESDAY: Broken cloud cover, daytime high temp around -10 C, light wind generally out of the south, trace of snow possible.
THURSDAY: Broken cloud cover, daytime high temp around -12 C, light wind generally out of the west, no significant snow expected. It looks like there could be an extreme wind event in store for the region Thursday night with extreme wind out of the southwest, a few cm of snow are expected Thursday night too.
FRIDAY: Broken cloud cover, daytime high temp around -10 C, strong to extreme south/southwest wind, no significant snow expected.
Avalanche Summary
We do not have any recent avalanche observations. There may have been some avalanche activity during the day Tuesday. The amount of new snow is right at that threshold where there may have been some activity, or maybe not. If you're out and about, please send us your observations via the Mountain Information Network (MIN).
Avalanche control work on Saturday produced many large wind slab avalanches on NE facing features around 1700 m. Most of these avalanches stepped down to weak facets and rocks.
On Nov 30, a size 2.5 skier-remote persistent slab was reported on the MIN (see report here). The avalanche was triggered from around 100m away, by a group of 5 riders on an east aspect at 1400m. The avalanche was suspected to have failed on an early-season facet/crust layer.
Snowpack Summary
The storm was a bit less productive than expected, we've picked up 15 to 20 cm of settled storm snow from the system as of Tuesday afternoon. The weather stations aren't showing much wind, but we got one observation of some ridge top transport. We're very short on observations right now, but Tuesday's storm snow probably rests on a combination of heavily wind effected surfaces and maybe some facets.
A facet/crust layer can be found near the bottom of the snowpack. This layer was reactive to human triggering last week with a notable skier-remote avalanche on November 30th.
Snow depth at treeline is approximately 80-120 cm, depths in the alpine range from 100-200 cm.
Terrain and Travel
- Start with conservative lines and watch for clues of instability.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Storm Slabs
The region picked up 15 to 20 cm of new snow Tuesday with enough southerly wind to form fresh and potentially sensitive storm slabs that are going to be most problematic in north facing terrain where it has likely been formed into slabs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Tuesday's storm didn't come through with enough snow to have any meaningful effect on the deeply buried weak layer in our snowpack, so this one continues to be a bit of a mystery, as there is very little recent information about the sensitivity and distribution of this layer. This much uncertainty should push you into forming pretty conservative travel plans.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 8th, 2021 4:00PM
