- Date
- Friday, November 20, 2020
Storms over the past week exceeded expectations in many areas and have gone a long way to helping build up our early season snowpack.
Most of our forecast regions now show some variation on the theme of 15-50 cm of lower density new snow sitting on a temperature crust that formed during the recent march of storms across the province.
In the Northwest, a group of backcountry travelers has been doing a great job of tracking avalanche activity on a layer of surface hoar that managed to grow on the aforementioned temperature crust before being buried. This is definitely one to watch for if you are recreating in these regions. Check out the recent MIN reports and the local social media groups for details and images. Our most recent info on this problem is a few days old now, but I’d operate under the assumption this layer is still reactive to human triggering and choose low consequence terrain to investigate the situation. Keeping the spatial variability of surface hoar distribution in mind should prevent you from drawing any broad conclusions. Observers in the Northwest Inland have additionally noted significant wind loading on west and southwest aspects in exposed areas as a result of recent winds.
Surface hoar glimmering on the bed surface of an avalanche in the Shames backcountry
Photo: Travis Carter
Folks in the South Coast regions have been producing encouraging descriptions of 25-30 cm of new snow bonding well with the crust below it at lower, warmer elevations. This picture seems to worsen at higher elevations where wind loading has been a significant contributor to snowpack structure and where surface snow was less likely to be warm, moist, and sticky when it was buried by the latest snowfall. Recent reports that give a good indication of conditions in all three of these regions can be found on the MIN.
Interior regions are sporting some of the greatest snowpack depths in the province, with snowfall hotspots in the central Monashees and high Selkirk zones like Rogers Pass edging gradually toward a two metre-deep snowpack. Snowpack depths reduce toward the northern Cariboos, the Purcells, and the Kootenay Boundary. Across all interior regions,15-50 cm storm slabs can be found on the surface, they have shown reactivity to human triggering and in snowpack tests, and the more deeply buried early November crust is still very much on the radar. Up to 120 cm of storm snow has been observed over this layer in deeper snowpack areas and it too continues to react in snowpack tests. Shallower storm slabs have also been observed stepping down to this layer in Rogers Pass. I’d have it at the top of my mind when traveling anywhere near big, steep alpine features.
As for the Rockies, the southern portion around Fernie was a bit warmer during the recent storms and only holds about 10 cm of new snow above a rain crust. Snowpack depths here hover around 70 cm, not unlike shallower parts of the Purcells and Kootenay Boundary. The North Rockies seem more in line with the northern interior ranges with snowpack depths around 80-120 cm, but observations here are few and far between. Be sure to check existing MIN reports in this part of the world to get a baseline understanding of snowpack conditions before heading out and to travel with a mindset of ‘initial assessment’.
The Yukon is a clear outlier among these regions. Brutal winds recently blasted surface snow in White Pass into a moonscape of sastrugi and boilerplate crust. These conditions are likely to keep you away from any terrain steep enough for an avalanche.
Big storms to weekend clearing
Taking a look at Friday’s Mountain Weather Forecast, we can see there is a good chance for skies to clear on Saturday and Sunday as a ridge of high pressure pushes over the province. This should make for a beautiful couple of days to be in the mountains, but it will be essential to keep in mind that even if the mountains are in the clear, backcountry travelers are most certainly not. We’re currently operating in increasingly complex snowpack conditions without one of the key decision-making tools that is normally available to us - an avalanche forecast.
Lacking certainty in the snowpack, we need to reach for that certainty elsewhere. The surest place to find it is in our analysis of terrain. Choosing terrain where avalanches are unlikely to occur and where the consequences of an avalanche are low stacks the odds in your favour. There’s another big storm pulse on the way before our November 25 forecast launch, so keep your guard all the way up as we head into the last week of the month.
Teamwork makes the dream work
I doubt I’m the only one who has noticed that the Mountain Information Network has been in top form in the past two weeks. Reports from all over western Canada have been showing up on the MIN in record numbers. We have never seen it this busy at this time of year before!
Along with quality conditions reports and images, we are seeing excellent avalanche incident reporting. This is not a time to be shy about sharing your run-in with unstable snowpack conditions and looking at the MIN today shows that AvCan users get it. Your decision to share this information is potentially life-saving for the party that has a chance to check it out before heading out to the same area. Keep it up! This is the kind of collaboration we’re going to need all season as we head into a winter of limited data flow and as we battle the COVID-19 pandemic together.
Having a safe season this year is going to take more team spirit than it ever has before. If we’re diligent about working together, sticking to public health orders, and minimizing the need for SAR callouts, there’s a lot to look forward to this season. If we ease up on these practices, the consequences loom large.
Colin Garritty