Avalanche Forecast
Issued: Dec 2nd, 2018 3:46PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
cgarritty,
Avalanche Canada
Waiting for a persistent slab problem to stabilize isn't great fun, but it's better than getting caught pushing the conditions. Check out our Forecasters' Blog here for advice on managing current conditions.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Sunday night: Mainly cloudy. Light west winds. Monday: A mix of sun and cloud. Light northwest winds. Alpine high temperatures around -10.Tuesday: A mix of sun and cloud, becoming more clear over the day. Light to moderate northwest winds. Alpine high temperatures around -9. Wednesday: Mainly sunny with some valley cloud. Light northeast winds. Alpine high temperatures to around -8 under a mild temperature inversion.
Avalanche Summary
No new avalanches were reported in the last week. Two MIN reports from November 24th are worth your consideration though:This one describes a rider getting caught and carried in a small storm slab in the Ymir bowl area. This one details a group of riders triggering a large deep persistent slab avalanche in Meadow Creek which is in the neighboring South Columbia region. Multiple folks were involved, but thankfully everyone survived.Huge thanks to everyone posting to the MIN, please continue to do so here.
Snowpack Summary
The storm last weekend delivered 20 to 40 cm of snow that has settled out to about 30 cm of soft snow on the surface. At treeline, the total height of snow is now between 100 and 140 cm. At 40 to 80 cm below the surface there is a persistent weak layer that was buried on November 21st. This weak layer consists of surface hoar (feathery crystals) in most places, but may present as a sun crust on steep south facing slopes. This layer has been reactive in snowpack tests this week. A MIN report from the Kootenay Pass area (link here) and a social media post (link here) from the Whitewater area on Thursday also show a concerning degree of reactivity at this layer. This surface hoar is thought to be widespread at treeline and it may be found in sheltered alpine features too.At the base of the snowpack is a thick melt-freeze crust that formed near the end of October. This crust has shown limited reactivity thus far, but observations are very limited.
Problems
Persistent Slabs
Storm snow from the past couple of weeks is consolidating into a slab that rests on a persistent weak layer 40 to 80 cm below the surface. This layer seems to be most prevalent at treeline, but likely extends into the alpine in sheltered terrain.
Smaller avalanches in motion may step down to deeper layers resulting in large avalanches.Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.Back off if you encounter signs of instability such as whumpfing, cracking, or recent avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 3rd, 2018 2:00PM
