Avalanche Forecast
Issued: Dec 20th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
kdevine,
Avalanche Canada
It's a great weekend to hit the ski hill! Widespread avalanche activity is expected today. Avoid avalanche terrain.
Summary
Confidence
High -
Weather Forecast
FRIDAY NIGHT - Periods of snow, 10-20 cm / southwest wind, 20-40 km/h / alpine low temperature near -5
SATURDAY - Periods of snow, 15-25 cm / southwest wind, 20-40 km/h / alpine high temperature near -3 / freezing level 1000 m
SUNDAY - Cloudy with sunny periods / southeast wind, 10-20 km/h / alpine high temperature near -8
MONDAY - A mix of sun and cloud / northwest wind, 10-20km/h / alpine high temperature near -9
Avalanche Summary
With ongoing snowfall and strong winds expected on Saturday, a widespread avalanche cycle is likely to continue throughout the day.
Observations on Friday were limited due to intense storm conditions, but it is likely that a natural avalanche cycle was occurring throughout the day.
There were numerous reports on Thursday of natural, explosives and human triggered avalanches up to size 3. Many of these were triggered remotely.
Previous heavy snowfall resulted in an avalanche cycle on Tuesday and Wednesday. Numerous natural and human triggered avalanches up to size 2.5 were reported
Snowpack Summary
The storm rages on in the North Columbias with 10-20 cm overnight on Friday, and another 15-25 cm expected during the day on Saturday. By the end of the day on Saturday, this will make for a total of 40-75 cm of snow in 48 hours. Storm slabs are expected to be widespread and very reactive.
There is anywhere from 100-160 cm of snow on top of a widespread layer of large, feathery surface hoar crystals. With more snow continuing to accumulate above this layer, it will likely remain very sensitive to human-triggering.
A weak layer that formed in late November is now over 170 cm deep. This is the layer of concern relating to the persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. Below this, a variety of crusts from late October are buried deeper in the snowpack..
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Avoid the runout zones of avalanche paths. Avalanches could run full path.
Problems
Storm Slabs
Continued intense loading from heavy snow and strong winds will mean that an avalanche cycle is almost certain. Avoid avalanche terrain, and don't underestimate the potential for avalanches to run full path.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A couple of weak layers formed in late November and early December are now over 100 cm below the surface. This layer may present as surface hoar, a crust, facets or a combination of those, depending on elevation and aspect.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 21st, 2019 5:00PM
