The Good and Bad of Crusts.

Can the Dreaded November Raincrust Actually Be a Good Thing?

It’s a magical time every year when Calgarians first look west and notice the Rocky Mountain peaks are once again white. It’s a time when mountain bikers are hammering their final rides of the season, and skiers are starting to dig out Goretex, wax up skis, and generally get fidgety. The earlier it snows in the hills, the better, right? Not so fast.

The young and the stoked get excited whenever that first flake flies, but the old and jaded wonder if it isn’t’ a bit too early. They know that a layer of snow that sits for too long, waiting to get covered by more white, runs the risk of becoming an avalanche hazard that could last the entire season. One way or the other, it has a direct impact on your ski season regardless of whether you ski the backcountry or the ski resorts.

Lake Louise by Reuben Krabbe / SkiBig3


This year, like in most years, the Rockies had a few unremarkable dustings of snow in October. Sometimes these early snows melt away in warm autumn lulls. Other years they stick around long enough to be covered by November storms and become preserved for the entire winter. That’s what happened this year when approximately 20 centimetres lay on the local slopes as a storm approached during the first week of November 2020. 

That storm blasted in from the coast, warm and wet. It rained right to the top of the local ski hills, melting the surface snow into slush. As the storm moved on, that surface froze hard. By Nov. 5, fresh snow blanketed this ice layer and mummified it; to haunt, or help, skiers later.

Any layer in the snowpack gets named on the day it becomes buried. Depending on what report you look at, this crust of ours is called the Nov. 4, Nov. 5, or Biden crust. 

On the good side, a hard crust that carries a skier’s weight keeps them from wrecking their skis (or bodies) by dry-docking or scraping rocks. This year skiers have been able to ski many runs that usually could not open with such little snow thanks to the Nov. 5 crust. For example, ER 3 at Lake Louise is a scree and boulder field that would typically need well over a metre of snow to open safely. This season it opened early, with much less than a metre, and it skied well! Sunshine Village has seen similar benefits from the crust, allowing them to open big swaths of terrain earlier than usual.

Early season bootpacking with M-T-N Guiding

The ease of travel afforded by our friend the Nov. 5 rain crust has been a boon for backcountry skiers as well. Creeks and forests are typically the barriers adventurous skiers must break through to gain the good early season skiing in the alpine. This year those character-building experiences have been much more manageable. Even in areas with only 30 centimetres on the ground, a careful skier can travel fairly easily right now.

So what’s the downside, you might ask? Avalanches.

A sheet of ice buried below creates a sliding surface ripe for repetitive avalanche cycles. It’s the kind of layer that isn’t likely to truly disappear until the summer, and any new storm or weather change runs the possibility of producing avalanches on it. The Dec. 3 Parks Canada Avalanche Bulletin warns, 

“The Nov 5 crust has facets above and below it, and exists up to 2500m on shady aspects and higher on solar aspects. We have seen a few isolated avalanches on this layer so use caution.”

photo: Scott Thumlert

Backcountry skiers can expect to see this “Deep Persistent Avalanche Problem” listed in bulletins for much of the winter. It’s the type of avalanche problem that is hard for experts to predict, leading to a lot of uncertainty. That kind of uncertainty leads to fear instead of fun. There will be many backcountry skiers scared of steeper slopes as the season goes on, and many more that probably should be. 

But even skiers who spend their entire season inbounds at the ski resorts will be affected by the Nov. 5 crust. Up to this point, it has had a positive impact and led to some fantastic November turns! But as it gets buried deeper and deeper, patrol and avalanche teams will need to throw more bombs and wait longer to open or re-open terrain due to the uncertainty it creates.

Having an early-season rain crust is nothing new in the Rockies. It’s almost the norm, to be honest. This Nov. 5 friend of ours is just an excellent example of it. In other seasons where a crust like this exists at the base of the snowpack, these layers have awoken and produced big avalanches later in the year—even into late spring.

So, don’t be surprised if in April, on a warm, beautiful spring skiing day, you arrive ready to ski your favourite bowl or steep run at the resort only to find it closed for avalanche danger. If you take the time on that day to research conditions (say at avalanche.ca), you may see your new friend, the Nov. 5 rain crust, blamed for the danger. Feel free to curse him at that point, but don’t forget the great season we’ve been having so far, thanks to his presence!

Banner photo: Sunshine Village by Reuben Krabbe / SkiBig3