Avalanche Forecast
Issued: Nov 28th, 2019 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
astclair,
Avalanche Canada
Where there is enough snow to recreate, the snowpack is highly variable. 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, light northeast wind, alpine temperature -16 C, no precipitation.
Friday: Clear skies, light northeast wind, alpine temperature -12 C, no precipitation.
Saturday: Mix of sun and cloud, light variable wind, alpine temperature -10 C, no precipitation.
Sunday: Mix of sun and cloud, light southwesterly wind, alpine temperature -8 C, no precipitation.
Avalanche Summary
There have been reports of human and explosive-triggered avalanches on north-facing alpine terrain in the past few days and releasing to the ground. 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
With this week's clear, cold, and dry 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 10-30 cm of recent snow into wind slabs that may still be possible to trigger. These slabs could be particularly touchy where they overlay 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.
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 the weekend storm here.Â
Problems
Wind Slabs
Since the weekend storm, strong and variable winds have redistributed the 10-20 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
Expected Size
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, Treeline.
Likelihood
Expected Size
Valid until: Nov 29th, 2019 5:00PM
