Triggering avalanches may become more likely throughout the day as new snow piles up. Watch for signs of instability such as whumphing, cracking and recent avalanches.
15-50 cm of snow may sit above a layer of surface hoar and/or crusts. This layer will likely be reactive to human triggers in areas with 30+ cm of snow on top of the weak layer.
MONDAY NIGHT - Cloudy with scattered flurries, up to 5 cm / light southwest wind / alpine low temperature near -10
TUESDAY - Cloudy with flurries, 5-10 cm with another 5-10 cm overnight / southwest wind, 20-40 km/h / alpine high temperature near -6
WEDNESDAY - Mainly cloudy with flurries, 5 cm / southwest wind, 20-50 km/h / alpine high temperature near -7
THURSDAY - Cloudy with flurries, 5-10 cm / southwest wind, 20-40 km/h / alpine high temperature near -7
There have been a few recent reports of small avalanches above the recently buried surface hoar and crust layers. These include several dry loose avalanches in steep terrain, some small naturally triggered slab avalanches on solar aspects, and a few size 1 skier triggered avalanches in the Selkirks. The skier triggered avalanches were 30-40 cm thick (see the photo in this MIN report).
While these avalanches have limited destructive potential, we anticipate this developing into a more concerning problem with the arrival of more snow.
Up to 15 cm of snow is expected between Monday night and Tuesday afternoon, bringing totals up to 15-50 cm of snow now sitting on a weak layer that was buried about a week ago.
This weak layer is variable, in some areas exists as a layer of feathery surface hoar, while in other areas it exists as a crust - either a sun crust on south facing slopes, or a melt-freeze crust at lower elevations.
In western and southern parts of the regions (e.g. the Monashees and Revelstoke area), the melt-freeze crust has been reported to extend into the alpine, with about 5-15 cm of fresh snow above it. Further east and north, 25-50 cm of snow likely sits on the surface hoar layer.
The primary concern is for any area where 30+cm of snow sits on top of the weak layer, regardless of whether it is surface hoar or a crust.
Another buried crust can be found in the lower snowpack (50-150 cm deep) with some reports of weak snow around this crust. There have been no recent avalanches reported on this layer, however occasional test results indicate that it may be reactive to human triggers on shallow rocky features at upper elevations.
