Avalanche Forecast
Issued: Dec 14th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
lbaker,
Avalanche Canada
We now have two concerning persistent weak layers within our snowpack.
Be aware that if triggered, avalanches may step down to deeper layers resulting in large, destructive avalanches. Keep your terrain choices conservative and be prepared to back off quickly if you find signs of instability like whumpfing and shooting cracks.
Summary
Confidence
Avalanche Summary
On Tuesday, explosives control in the Monashees produced a few avalanches below treeline up to size 2.
On Monday, several, size 2.5 natural persistent slab avalanches were observed in the Kaslo region. Explosives control throughout the Selkirks triggered size 2.5 avalanches on the mid-November weak layer.
On Sunday, numerous surprise human-triggered avalanches were reported on the persistent weak layer between 2200 and 1700 m. The spookiest reports on this layer are of a skier remote avalanche, size 3, at Kokanee Glacier and a skier sympathetic avalanche, size 2.5 in the Kaslo region. These avalanches either failed on the November weak layers or 'stepped down' from a smaller avalanches onto these deeper instabilities.
Snowpack Summary
Snowpack depths average 80-160 cm in the alpine.
Surface: 5 - 10mm surface hoar has formed on the surface of the snowpack. A sun crust is found on steep solar slopes. Previous southerly winds have created wind slabs in exposed lees and cross-loaded features at higher elevations.
Upper-pack: A 30 - 40 cm soft slab overlies a small layer of surface hoar in sheltered and shaded terrain and a sun crust on sunny south-facing slopes.
Mid-pack: A weak layer of large surface hoar crystals, facets and a melt-freeze crust sits 50-80 cm deep, buried in mid-November. This layer has been very reactive at treeline between 1700-2200 m, on all aspects producing large remotely triggered avalanches. This layer will likely continue to be reactive through the week as northerly winds build wind slabs adding additional load to the weak layer.
Lower-pack: Below the mid-November layer is a generally weak, faceted snowpack.
Weather Summary
Wednesday Night
Partly cloudy skies. Northerly ridge wind 20 - 30 km/hr. Alpine temperatures, high of -10. Freezing levels valley bottom.
Thursday
Scattered clouds. Northerly ridge winds 20 km/h gusting to 40 km/hr. Alpine temperatures, high of -7. Freezing levels 600 m.
Friday
Partly cloudy skies. Northwesterly ridge winds 30 km/h gusting to 50 km/h. Alpine temperatures, high of -9. Freezing levels valley bottom.
Saturday
Cloudy skies. Light flurries, 2 cm accumulation. Northeasterly ridge winds 20 km/h. Alpine temperatures, high of -9. Freezing levels valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
- Don't let the desire for deep powder pull you into high consequence terrain.
- Minimize exposure during periods of heavy loading from new snow and wind.
Problems
Persistent Slabs
There are now two persistent weak layers within the snowpack.
A 30 - 40 cm soft slab sits above a weak layer of surface hoar on shaded aspects and crust on steep solar aspects. Although natural avalanche activity has tapered off on this layer, human-triggered avalanches are possible.
A second weak layer of surface hoar and facets from mid-November is buried down 50 to 80cm in the region. This layer continues to catch professionals and recreationists off guard with numerous large human-triggered avalanches.
Read our featured blog to learn more about how to manage a persistent slab problem when traveling in the backcountry.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 15th, 2022 4:00PM
