Avalanche Forecast

Issued: Nov 28th, 2019 4:00PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada astclair, Avalanche Canada

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Clear and cold for the next few days. The most likely place to trigger avalanches is where the wind has formed slabs at higher elevations.

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

Thursday night: Clear skies, alpine temperature -15 C, light northeast wind, no precipitation.

Friday: Mostly sunny, alpine temperature -10 C, light northeast wind, no precipitation.

Saturday: Mostly sunny, alpine temperature -8 C, light variable wind, no precipitation.

Sunday: Mostly sunny, alpine temperature -8 C, light southerly wind, no precipitation.

Avalanche Summary

The most likely place to trigger avalanches right now is where the wind has drifted snow into stiff slabs in the alpine. This is a great MIN report from the neighboring South Columbia region that helps to paint the picture of these wind slab avalanches. 

Observations are limited this time of year, so there is a fair bit of uncertainty about the extent of current avalanche activity. If you see anything while out in the field, please consider sharing that information with us and the backcountry community via the Mountain Information Network.

Snowpack Summary

Snow line sits around 1200 m, and snow depths range from 90-140 cm at treeline elevations.

With this week's clear and cold weather, the weekend storm snow is losing strength, except where it has been drifted into wind slabs in the alpine. Variable winds have redistributed the 20-30 cm of recent snow into wind slabs that may still be possible to trigger. These slabs could be particularly touchy where they overly a weak layer of surface hoar (feathery crystals) that formed last week. This "Nov. 23 crust" has produced repeatable sudden or propagating results in snowpack tests. With few field observations, uncertainty remains on the distribution and reactivity of these layers.

A variety of crusts from late October are buried deeper in the snowpack (down 60 to 100 cm). The inactive weather pattern this week also promotes a decreasing trend in reactivity for these layers.

Problems

Wind Slabs

An icon showing Wind Slabs

Since the weekend storm, strong and variable winds have redistributed the 20-30 cm of snow into cohesive slabs that may still be possible to trigger in the alpine. These slabs could be particularly touchy where they overly a weak layer of surface hoar that formed last week.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Nov 29th, 2019 5:00PM

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