Avalanche Forecast
Issued: Nov 22nd, 2019 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
ghelgeson,
Avalanche Canada
Considerable alpine danger is based on storm snow totaling 20+ cm by Saturday afternoon which is expected to do two things:
1. Create a touchy storm slab problem.
2. Potentially wake up the persistent slab problem.
Prepare for rapidly changing conditions and increasing hazard.
Summary
Confidence
Low - Uncertainties in both the snowpack structure and the weather forecast limit our confidence.
Weather Forecast
It’s late November and this weather pattern looks to bring winter to our doorsteps this weekend. The region should get a nice re-fresh from the system.
FRIDAY NIGHT: 5 to 20 cm of snow possible with greater accumulations in the north of the region, freezing level holding around 1400 m, strong southwest wind.
SATURDAY: Storm day, visibility is likely to be poor, freezing level around 1500 m, strong west/southwest wind, 5 to 20 cm of snow possible, with another 10 to 20 cm possible Saturday night.
SUNDAY: Broken cloud cover, freezing level around 1300 m, moderate west wind, 5 to 20 cm of snow possible.
MONDAY: Broken cloud cover, freezing level near valley bottom, light northwest breeze, no significant snowfall expected.
Avalanche Summary
No recent avalanche activity has been reported. A natural avalanche cycle is possible late Saturday as storm snow begins to stack up on a weak and variable snowpack.
Snowpack Summary
Winter is slowly descending to the valleys with about 90 to 120 cm of snow present around 2000 m.
There are likely a variety of crusts in our young snowpack, but a problematic rain crust down about 50 cm is beginning to stand out. This "October Crust" is showing sudden & repeatable results when subjected to snowpack tests. Avalanches failing on this interface have the potential to be large and could easily suprise users who are getting out onto snow for the first time this season. There's a great summary of conditions at Allan Creek here.
Problems
Storm Slabs
Storm totals could easily exceed 20 cm Saturday afternoon and this system has a fair amount of wind associated with it too. Conditions will likely change rapidly over the next 24 hours and storm snow is not expected to bond well to the old surface, avalanches in motion could step down to more deeply buried weak layers too. Frankly, we don't know much about this snowpack right now, and we don't trust it. Keep it conservative on Saturday people.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A problematic crust can be found about 50 cm below the surface. This "October Crust" is showing sudden & repeatable results when subjected to snowpack tests. This weekend's storm cycle will be a great test for this interface and should reveal a lot. That being said, we don't trust it and conservative terrain choices are the best defense this weekend.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 23rd, 2019 5:00PM
