This past week has been wintery in the west, with overnight lows in the alpine nearing -20°C and little storms bringing in small but constant amounts of snow in the Rockies and Columbia mountain ranges. In the Rockies, treeline snow depths are now above threshold for avalanches (50 cm+) and in the Rogers Pass area you can expect up to double that. Alpine snow depths are over a meter in the Rockies and over 150 cm around Rogers Pass.
Avalanche hazard is steadily rising and is a real concern now. The weak layer that everyone is talking about is the Oct 25/26 melt-freeze crust and the underlying facets.
In all areas this layer has been producing whoompfing and sudden collapse test results below a slab of anywhere from 20 to 60+ cm which is concerning. More concerning is the fact that it is now producing skier triggered avalanches up to size 2.5 or even 3.0, which are considered large/very large and deadly.
It is a thick (4+cm) facetted layer that will not heal on it own and will only present less of a hazard after avalanche cycles and bridging from future snowfalls over a long period of time (likely weeks+) -- the textbook definition of the term "Persistent Weak Layer" and now in many places more of a "Deep Persistent Weak Layer" (>100 cm deep). It will continue to be a problem for a while yet, getting worse before it gets better. During this transition time, the frequency of avalanches will become less but the destructive power and uncertainty will increase: a time for using restraint and caution.
A newer layer from around November 2 is also present, about 4 cm thick crust in the Rogers Pass area and less prevalent in the Rockies.
In short, we have a long winter ahead of us, so please be especially careful in the coming weeks.
Other hazards include early season nuisances like rocks and logs that are thinly covered by faceted snow (below treeline skiing is still grim) as well as crevasses that may be lightly bridged with faceting snow. For hikers on popular trails, it's getting really slippery and crampons or cleats are mandatory on the well-frequented steep paths. And of course days are getting shorter and colder, requiring different planning and gear.
WHAT TO DO
Ski quality has improved with the snowfall over the past few days and especially overnight. Getting to the goods will still require effort as below treeline there isn't enough snow for reasonable travel. Expect to deal with lots of thin and facetted snow until you get at least to treeline. Reports of alpine skiing have been positive, with the expected caveats.
Ice climbing is starting to pick up momentum, but again it's early season and we've got a long winter ahead of us. Climbs are coming into better and better condition, and meanwhile avalanche hazard in the snow belt is dubious. While you're waiting for the Sign, there's lots of mixed climbing that is relatively safe and will get you strong for your big projects. Alternately, there are many front range ice climbs coming in where avy hazard is still below threshold.
Hiking and mountain biking are pretty much out now with the continued snowfalls. Fat tire biking and cross country skiing are better bets.
MOUNTAIN INFORMATION NETWORK
I'd like to close with a plug for the Mountain Information Network. You can access the MIN at www.avalanche.ca. There you will find a wealth of information on current conditions (via MIN reports as well as remote weather stations) and avalanche summaries all in one incredibly easy map interface.
Many of us use the MIN as a source of information, but Avalanche Canada would like to encourage each and every one of you -- yes, YOU! -- to also submit your observations. The submissions interface is simple and streamlined and doesn't have to take you much time at all. Your observations are extremely valuable, especially during data-scarce periods like the autumn shoulder season. So please -- go to the site right now and try it out! Thank you in advance for your help with advancing public mountain safety in western Canada.
This is the last weekly summary report we'll be putting out for the season. Guides will still be submitting periodic reports to the MCR, and of course yur best source for conditions summaries in the winter, as always, will be found at avalanche.ca
Mountain Guide ACMG/IFMGA