ACMG Mountain Conditions Summary for the Rockies and Columbia Mountains November 20, 2020

Posted on Fri, 20/11/2020 – by Tom Wolfe


The main avalanche problems are windslabs (to size 2) and a deeper Persistent Slab (to size 3 on the Nov 4/5 layer). Avalanche Hazard is Considerable (3 / 3 / 2) which means it’s a tricky, dangerous time to be in the mountains.

The windslabs are big enough to be deadly, and we are right at the critical load point over the November 4 crust for big human triggered avalanches. Another 10+ cm of snow with mild below-freezing temperatures and little wind is in the forecast. I hope that the parks bulletins as well as reports coming in on the MIN of skier triggered avalanches will urge skiers to dial it back a bit and take it easy this weekend.


This past week has been mild and snowy with wind. This new snow is adding mass over top of the November 4 layer which some are calling “Biden Crust” and others the “Trump Persistent Weak Layer”. Regardless of your biases this layer is a problem that’s likely to be with us for a while yet.

This crust was formed by rain and warm weather earlier in the month, and as happens with these crusts there are facets forming above and below it to make it an even weaker layer.

Right now in the interior (Selkirks) the storm snow has buried the Nov crust down 50 to 100 cm. In the Rockies it’s a similar situation, divided roughly in half. The Nov 4 layer is down 30-60+ cm.

Skier triggered avalanches in the interior and the Rockies have been either in the windslabs or the deeper layers. The Nov 4 crust is still being triggered by skier traffic where it is more shallowly buried. There is also the risk of smaller storm and wind slab avalanches stepping down to the Nov 4 crust in deeper snowpack areas making for some very large skier triggered avalanches.


I think we’ve dealt with the avalanche hazard. Be careful out there.

The glaciers are getting covered pretty well for this time of the year and crevasses will be well hidden. But 100 to 150 cm of fresh autumn snow doesn’t make for great bridges and there will be many places where a skier could punch through.

Cornices are getting large and tender, a result of the recent snowfall and wind. Getting hit by even a small cornice would be no fun, and there’s also a risk of a cornice failure causing an unexpectedly large natural avalanche.


Judging by today’s ski conditions and the forecast there should be plenty of good turns to be had across the Rockies and the Interior over the next few days. Finding deep snow will be key. Below treeline it’s still pretty rugged. Stick to lower angled, supported terrain and be cautious of terrain traps and the runouts of larger avalanches overhead in the event of a big natural avalanche.

Ice climbing is in good early season shape now in the Rockies. I would be cautious and avoid routes with overhead hazard and think carefully before crossing above cliffs. Loose snow avalanches and large sluffing will also be a concern for ice climbers this weekend.

This is it for MCR Summaries for 2020. What a crazy year. Stay safe and keep your fingers crossed for things improving in 2021. Avalanche Canada will start publishing bulletins on November 25, just a few days away.

I want to encourage all of you this winter to please take a moment after every ski trip to make a post, however brief, to the excellent Mountain Information Network (MIN) at It is quick to get setup and it’s really easy to figure out.

With the slowdown in the ski guiding industry due to covid, this year more than ever Avalanche Canada needs all of the data it can get to create its bulletins. Whether you get caught in an avalanche or just experienced that best powder skiing of your life, the MIN and Avalanche Canada will benefit from your observations — which means we will ALL benefit.

See you in the spring!

Tom Wolfe
ACMG Mountain Guide

Photo courtesty of Nino Guagliano. Me on Guinness Gully / High Test this past Monday. Both are in great early season condition.

Do you have time for an avalanche course this winter? I have room on my Dec 18-20 Avalanche Skills Level 2 Course for you! Classroom sessions are held earlier in the week in two shorter evening Zoom sessions. If you would like to join us, please use my booking form or the green text widget at the bottom of this page to contact me.

Ski Trip Planning Forms

The most important decisions happen before you even put your skis on. Your goals for the day are a distillation of all that’s important: group composition, current conditions, weather forecast, avalanche problems, avalanche forecast, and the unique combination of skills, aspirations and risk tolerances of your group members. If you miss any of these things you run the risk of having an unsuccessful or risky day.

The guiding industry has learned many lessons from other industries over the years. Surgeons and airline pilots, both experts in risk management, use checklists. We have done likewise, and it’s make a huge positive impact on the quality of our decision making and ultimately the safety of our clients and ourselves. If they are useful for us as guides, they can be useful for everyone and this is the reason that AST courses have useful checklist-style tools like the Avaluator and Trip Planning forms.

Here are a few forms I use that serve as checklists to frame my decision making and conversations with my ski partners, co-guides and clients. I have structured them so that the most important considerations come first: weather, avalanche, and group factors are the starting points and those lead eventually to a solid plan.

If you find these forms useful, or if you have any suggestions on how they can be improved please don’t hesitate to contact me.

Here’s a link to my Resources Page which has a bunch of weather sites, weather datalogger links, equipment lists, and other handy things as you plan to head out into the mountains.

Feel free to contact me if you have any questions about planning your trip this weekend. If you’re looking for a course, I’m offering AST1 & Guided Backcountry Ski Days this winter!