Avalanche Forecast
Issued: Dec 20th, 2018 4:50PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
kdevine,
Avalanche Canada
As the storm eases off and temperatures drop, the snowpack is beginning to gain some strength. However, storm slabs are still likely to be encountered at upper elevations and could be reactive to human triggering, especially in wind loaded areas.
Summary
Confidence
Low - Due to the number of field observations.
Weather Forecast
THURSDAY NIGHT: Cloudy with clear periods, northwest winds, 30-50 km/h, alpine low temperature near -12°c. FRIDAY: Cloudy with sunny periods and isolated flurries, 5-10 cm on Friday overnight, southwest winds, 10-30 km/h, alpine high temperature near -8°c. SATURDAY: Cloudy with sunny periods, southeast winds, 30-40 km/h, alpine high temperature near -5°c, low temperature near -8°c. SUNDAY: Cloudy with flurries, up to 5 cm, southeast winds, 30-50 km/h, alpine high temperature near -5°c, low temperature near -8°c.
Avalanche Summary
On Wednesday a natural size 3.5 avalanche was reported north of Stewart on a south to southeast aspect at approximately 2000m. Also on Wednesday, a size 2 human triggered avalanche was reported on a northwest aspect at 1350 m near Ningunsaw. This avalanche was remotely triggered (triggered from a distance) and failed on the surface hoar layer that formed in early December.
Snowpack Summary
5-10 cm of new snow likely sits on a rain crust to approximately 1000m. Above 1000 m this new snow is sitting on the 100-150 cm of storm snow that came in over the past week. Previous strong winds have likely affected open terrain at higher elevations and formed thick wind deposits in lee terrain. All of this recent storm snow sits on an interface that was a concern during the start of the storm, but the strength of this layer has likely improved substantially over the past week. The interface is composed of surface hoar (feathery crystals), facets (sugary snow), and crusts that formed during the dry spell in early December. The surface hoar is most prevalent and is still showing reactivity in more northern portions of the region, and is something to keep in mind if you plan to travel to areas like Ningunsaw. Deeper in the snowpack, there are several crusts, including an early season crust with facets near the bottom of the snowpack.
Problems
Storm Slabs
Storm slabs have been building for the past week and could still be reactive to human triggering at upper elevations, especially on steep slopes in lee terrain.
Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.The new snow will require several days to settle and stabilize.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 21st, 2018 2:00PM
