Avalanche Forecast
Issued: Dec 12th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
bchristie,
Avalanche Canada
Continue to make conservative terrain choices. The recent storm left lots of snow available for wind transport. Moderate to strong winds have formed rider triggerable slabs.
Summary
Confidence
Weather Forecast
Temperatures are generally dropping, and winds are easing, but spotty precipitation continues, with the possibility of waking up to a pleasant refresh on Tuesday morning.
SUNDAY NIGHT: Mostly cloudy, with localized areas of clearing. 0-4 cm snow expected. Moderate to strong southwest wind. Freezing levels below 1000m. Alpine temps around -10
MONDAY: Mostly cloudy, possible breaks in cloud. 0-5 cm snow expected. Light to moderate south winds. Warming through the day, alpine high around -6 C.
TUESDAY: Partly cloudy. 2-10 cm of snow expected overnight, with a possible trace through the day. Light to moderate southwest winds. Alpine high around -8 C.
WEDNESDAY: Increasing cloud over the day. Possible trace of snow. Light to moderate southwest winds. Alpine temps around -13
Avalanche Summary
A size 1 skier remote triggered avalanche was reported that failed near the base of the snowpack on a north aspect in the alpine. This avalanche is small, but there were other deep failures reported in this region about a week ago. This is consistent with a deep persistent problem that may be difficult to trigger. We're not done worrying about this one yet.
Several size 1 and 2 natural avalanches were observed in the north end of the region yesterday. They seem to have failed within the storm snow.
On Wednesday, natural and skier triggered slab avalanches were observed at treeline and above to size 1.5.
Snowpack Summary
Moderate to strong southwest winds continue to redistribute 30-45cm of recent storm snow, forming reactive slabs. After the winds ease, these slabs will still need time to settle and become less reactive.
The new storm snow overlies about 50cm of settling snow from the last storm. This sits on a thick, supportive melt freeze crust on all aspects up to 2400m (December 2nd).
Where the December 2nd crust does exist, facets may be forming on top, making this a layer to watch.
A late October facet/crust layer of concern sits at the bottom of the snowpack above 1900m. This layer has been reactive to human triggers, producing large avalanches. This layer is widespread and will likely continue to be a layer of concern.
Average snowpack depth at treeline is 100-180cm, with the deepest snowpack found near the Bugaboos.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
Problems
Wind Slabs
Recent moderate to strong southwesterly winds have formed the recent storm snow into slabs that are deeper and more reactive in leeward features.
Aspects: North, North East, East, South East, North West.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A widespread weak layer of facets and depth hoar exists at the base of the snowpack above 2200m.
Avoid thin and rocky start zones where this layer may sit closer to the surface, and big open slopes capable of producing large avalanches.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 13th, 2021 4:00PM
