Avalanche risk high for South Coast with atypical weak layers causing major concerns

NORTH VANCOUVER (NEWS 1130) – The potential for large and deadly avalanches in mountains on the South Coast has triggered an extension of a special warning from Avalanche Canada.

The intense rain and snow over the last 48 hours has created a deeply unstable snowpack. Things are expected to be so unstable, on Tuesday, that forecasters are predicting a round of natural avalanches to slide through the region, and they could go big.

A natural avalanche occurs when snow slides without a human trigger such as a snowshoer, snowmobile or skier.

Monday’s warm temperatures resulted in rain and heavy, wet snow in the mountains, above 1200 metres. The precipitation added a ton of weight on top of already-weak layers, one of which is atypical for the region, according to Avalanche Canada.

“As we said in the original warning, this persistent weak layer is a concern because it is not typical for this region,” explains Avalanche Canada forecaster Kate Devine.

Forecasters worry about a buried weak layer that is "generally not found in this warmer climate. The recent snowfall has now put a greater load on that layer, which means it is deeper in the snowpack. When this weak layer is triggered, the resulting avalanche could be deadly."

— Ash Kelly she/her (settler) (@AshDKelly) February 2, 2021

The forecast details reveal a busy week for avalanche activity and search and rescue teams in the South Coast mountains, “with natural and/or human triggered avalanches reported every day since last Monday.”

At least 125 centimetres and up to 175 centimetres of snow is now sitting on top of an old rain crust and the atypical weak layers that could collapse if triggered by skiers or snowshoers.

“This weak layer consists of a crust that also has weak facets and surface hoar on top of it in many areas. This layer will probably take more time to gain strength than what is considered typical for the South Coast region,” says the forecast.

“In the rugged terrain of the North Shore Mountains and the popular backcountry areas of Vancouver Island, there are lots of places where this layer is a really big problem. We urge all recreational backcountry users to be extra diligent in their route finding and give yourselves a large margin for error when travelling in any type of avalanche terrain,” says Devine.

The avalanche risk is high for the alpine, treeline, and below treeline across the South Coast, with forecasters saying the risk is expected to last longer after the most recent storm than usual.

If you've not taken an AST 2 course, and/or lack experienced backcountry partners, if this is your first season or even your second or third… this is not the week for you to be out there. Knowing how to avoid avi terrain is a must today, as are companion rescue skills

— Ash Kelly she/her (settler) (@AshDKelly) February 2, 2021

Avalanche Canada says there have been natural or human triggered slides every single day over the past week, which has kept North Shore Rescue and other south coast SAR teams busy.

The experts say only the most simple, non-avalanche terrain free of overhead hazard is appropriate right now, and this is no time to be out there as a beginner or without avalanche safety training.

-With files from Meteorologist Michael Kuss