Avalanche Forecast

Issued: Nov 29th, 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 and Persistent Slabs.

Avalanche Canada astclair, Avalanche Canada

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Where there is enough snow to recreate, the snowpack is highly variable. The most likely place to trigger an avalanche is where the wind has formed slabs at higher elevations.

Share what you see in the mountains this weekend via the MIN!

Summary

Confidence

Moderate - Confidence is due to a stable weather pattern; little change is expected for several days. Uncertainty is due to the limited number of field observations. Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

Friday night: Few clouds, light easterly wind, alpine temperature -12 C, no precipitation.

Saturday: Mostly sunny, light variable wind, alpine temperature -9 C, no precipitation.

Sunday: Mix of sun and cloud, light southwest wind, alpine temperature -7 C, no precipitation.

Monday: Mostly cloudy, west wind increasing to moderate, alpine temperature -8 C, isolated flurries with 1-3 cm of accumulation possible.

Avalanche Summary

There have been reports of human and explosive-triggered avalanches on north-facing alpine terrain in the past few days releasing to the ground. The most likely place to trigger avalanches is where the wind has drifted snow into 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

With this week's clear and cold weather, last weekend's storm snow is losing strength, except where it has been drifted into wind slabs in the alpine. Variable winds previously redistributed the 10-30 cm of recent snow into wind slabs that may still be possible to trigger. These slabs could be more reactive where they overlay a weak layer of surface hoar (feathery crystals). With few field observations and substantial spatial variability, uncertainty exists as to the distribution and reactivity of these layers. 

Snowpack depth is highly variable, ranging from 10 cm to 100 cm. Expect to find weak facets (sugary, cohesion-less snow) in the thin areas. Elsewhere, you may find a melt-freeze crust from late October above faceted snow near the base of the snowpack. There's a great summary of conditions in Golden after last weekend's storm here.

Problems

Wind Slabs

An icon showing Wind Slabs

Strong and variable winds have redistributed the 10-20 cm of snow from last weekend's storm into cohesive slabs that may still be possible to trigger in the alpine. These slabs could be more reactive where they overly a weak layer of surface hoar that formed on a crust.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

Very little is known about some of the crusts and facets (weak, sugary snow) in the lower snowpack at this time. Current riding conditions are likely to push folks into the upper elevations where there is potential for riders to initiate avalanches failing on one of the more deeply buried crusts.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Nov 30th, 2019 5:00PM

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