Avalanche Forecast
Issued: Nov 24th, 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
20 to 30 cm of snow with strong wind has left us with two problems:
A potentially touchy storm slab.
A persistent slab that may remain sensitive to triggering.
Watch for signs of unstable snow and gather more info, especially if you're pushing beyond simple terrain.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations.
Weather Forecast
After a stormy weekend we’re transitioning to clearing skies, colder temperatures and no significant precipitation for the foreseeable future.
SUNDAY NIGHT: Freezing level dropping to valley bottom, moderate west/northwest wind, trace of snow possible.
MONDAY: Broken cloud cover, freezing level at valley bottom, light NW breeze, no significant precipitation expected.
TUESDAY: Broken cloud cover initially,scattered clouds in the afternoon, freezing level at valley bottom, light variable breeze, no significant precipitation expected.
WEDNESDAY: Clear skies, freezing level at valley bottom, moderate east wind, no significant precipitation expected.
Avalanche Summary
We're flying nearly blind here with very limited observations, but we suspect there was a natural avalanche cycle Saturday night into Sunday. If you were out this weekend please let us know what you're seeing by submitting to the MIN.
Snowpack Summary
Winter is slowly descending to the valleys with about 70 to 90 cm of snow at 1220m and 90 to 150 cm at treeline. Cornices are reportedly bigger than normal for this time of year.
Our data suggests the weekend storm produced 20 to 30 cm of snow accompanied by strong west/southwest wind, but there could be bigger accumulations of storm snow in favored locations. On steep south facing slopes in the alpine the new snow rests on a crust. A crust is also present on all aspects below 1600 m and many locations have surface hoar on top of the crust.
There are a variety of crusts in our young snowpack, but a problematic rain crust down about 50 to 100 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 surprise users who are getting out onto snow for the first time this season. There's a great "pre-storm" summary of conditions at Allan Creek here.
Problems
Storm Slabs
The weekend storm produced 20 to 30 cm of snow accompanied by strong west/southwest wind forming widespread storm slabs. These slabs rest on a variety of weak layers which will likely keep them susceptible to human triggering Monday, especially in bigger terrain near ridge crest.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Crusts that formed in late October are now buried 50 to 100 cm deep. We're working off of a short list of observations, but this late October layer is highly variable and may be associated with both surface hoar and facets. This is a layer to test and watch over the next week as good visibility and travel begin to sing the Alpine's siren song.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 25th, 2019 5:00PM
