Avalanche Forecast

Archived

Nov 28th, 2019–Nov 29th, 2019

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Cariboos.

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.

Confidence

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

Weather Forecast

Thursday night: Partly cloudy, 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 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 90-160 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 drifted the 20-60 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 sudden and repeatable 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 70 to 140 cm). The inactive weather pattern this week also promotes a decreasing trend in reactivity for these layers.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.