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 Wind Slabs.
shorton,
Avalanche Canada
New snow and strong wind will make triggering avalanches likely, especially on wind-loaded slopes near ridges.
Summary
Confidence
Weather Forecast
A cold front will bring gusty winds and 15-40 cm of low density snow on Wednesday.
TUESDAY NIGHT: Cloudy with flurries bringing 10-20 cm of low density snow, strong with from the southwest with gusts to 80 km/h, treeline temperatures around -10 C.
WEDNESDAY: Flurries continue with 5-20 cm of low density snow, moderate to strong wind from the west with gusts to 80 km/h, treeline temperatures around -10 C.
THURSDAY: Another 5-10 cm of low density snow by the morning then mostly cloudy skies throughout the day, moderate wind from the west, treeline temperatures around -12 C.
FRIDAY: Mostly cloudy, no significant precipitation, moderate wind from the southwest with gusts to 60 km/h, treeline temperatures around -10 C.
Avalanche Summary
Recent avalanche activity has mostly been small sluffs (aka loose snow avalanches) and thin soft slab avalanches running above the shallowly buried crust.
Last Thursday and Friday, there were a few very large deep persistent slab avalanches in the northern edge of the region near Blue River and Kinbasket Lake. These avalanches occurred in steep rocky north-facing terrain and failed on a deeply buried crust layer. One of the avalanches was triggered by a cornice collapse.
Looking forward, be on the lookout for low density snow becoming a more cohesive slab above the crust, especially in wind-affected areas.
Snowpack Summary
With 15-40 cm of fresh snow in the forecast, we can expect a total of 30-60 cm of low density snow above the crust that formed during last week's atmospheric river. This crust extends into the alpine (as high as 2400 m), and there is some concern about the bond of the recent snow to this crust. The surface snow should remain loose in sheltered terrain, but with strong winds in the forecast, we expect extensive blowing snow and the formation of fresh wind slabs at upper elevations.
The snowpack structure is relatively simple beneath the crust. Treeline snow depths are roughly 150-200 cm with an early November crust layer in the lower snowpack. While some faceting has been reported around this crust, it does not appear to be problematic at this point. The snowpack decreases rapidly below 1600 m.
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Avoid areas where the snow feels stiff and/or slabby.
- Closely monitor how the new snow is bonding to the crust.
- Be alert to conditions that change with elevation and wind exposure.
Problems
Wind Slabs
A frontal system crossing the region will form unstable wind slabs. These conditions will most likely be found on the leeward side of ridges, but pay close attention to the look and feel of the surface snow as slab formation could be more widespread. If slabs develop they could be poorly bonded to the underlying crust.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 8th, 2021 4:00PM
