Powder & Persistent Weak Layers
Last weekend winter roared back into our local mountains with 30-60cm's of new snow across our local mountains. We couldn't be happier about the return of winter, but with it comes some elevated avalanche hazard that could be challenging to manage. Let's get into it.
Ahead of last weekend's storms we had a prolonged drought through most of January. This set up a widespread crust and facet layer across much of the mountains that is now buried beneath fresh and wind distributed snow. This weak layer was reactive in various zones, with reports of propagating cracks and reactive wind slabs last weekend. The temperature also plummeted and the combination of weather and avalanche hazards has kept us skiing pretty conservative terrain.
Looking Ahead
As of today, we have two major avalanche problems in our local mountains. The first is a persistent slab problem where last weekend's storm snow has formed slabs overtop of the crust and facets from the previous weather. We also have a wind slab problem from the strong winds that have ripped through the Fraser Valley this week. And, this cold weather has also promoted surface hoar formation in protected areas, which means we could find the persistent slab problem in some unexpected places below tree-line.
While we're hopeful these problems will start to stabilize, the continued cold temperatures we're experiencing could slow that process down.
Looking ahead to this weekend, we're still going to be carrying a cautious mindset into the mountains. The big issue is the Persistent Slab problem, which can be very challenging to manage. I like the way Jeremy Jones talks about it, differentiating between Moderate avalanche hazard with and without a persistent slab, referring to the latter as "spooky moderate".
The issue becomes a low probability/high consequence scenario where, as Jones says, it "means a slide is unlikely, but if it does slide it will slide huge".
We'll be heading into this weekend looking at exploring a bit further, but very cautiously. This is a great time to dial in your terrain and snowpack evaluation skills before heading into any consequential terrain and to plan trips with plenty of Plan B's and Plan C's in safe, supported terrain.
In terms of the weather, the forecast is for a slight warm-up this weekend, but with temperatures still colder that we often see out here. We talked last week about thinking about cold as kind of terrain trap, which we're still going to be thinking about this weekend.
Upcoming Events
- Tonight we're holding a Winter Camping & Ski Traverse Workshop at Mt.Waddington in Chilliwack. Tickets are $10 with all proceeds to Chilliwack SAR.
- There are only a handful of winter courses still on deck, don't miss out if you want to build or refresh your skills!
