Avalanche Forecast
Issued: Dec 17th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
Danger ratings have decreased but concern still remains for deeper weak layers and wind loaded features.
Maintain your awareness as you transition through aspects and elevations.
Summary
Confidence
Avalanche Summary
Over the last 3 days, activity has been limited to small human triggered slabs specific terrain features, mostly on west facing slopes.
During the storm last Friday, explosive control produced persistent slab avalanches that failed on the mid-Nov crust down about 50cm. No avalanches have been reported on this layer since - however it remains a concern.
If you head out into the mountains, please share your photos or observations on the Mountain Information Network. Your information helps us understand local conditions!
Snowpack Summary
Pockets of wind slabs have developed from northerly winds at higher elevations, sitting over a thin crust. On north facing slopes, dense wind pressed snow can be found.
Two weak layers of concern sit in the snowpack:
A layer of surface hoar from early December is buried 30-50 cm deep below wind affected snow. This layer can be found in sheltered and shaded terrain features.
A widespread crust and facet layer from late November is buried 40-80 cm deep, found on all aspects and elevations.
Total snow depths remain low for December with 90 to 140 cm at treeline and up to 200 cm in the alpine. Much of the below treeline elevation band is below the threshold for avalanches.
Weather Summary
An Arctic front dominates the weather over BC. Light snowfall is expected Saturday night as a low south of Vancouver Island briefly competes with the cold air.
Saturday Night
Mainly cloudy with isolated flurries bringing up to 4 cm of snow. Freezing level at valley bottom. Moderate to strong northwest winds.
Sunday
A mostly cloudy day with another 5 cm possible, with heavier accumulations possible in Garibaldi Park. Moderate southwesterly winds. Alpine high of -15°C, freezing level below valley bottom.
Monday
Mostly cloudy with moderate westerly winds. Temperatures drop further, expect a high of -20°C. Isolated flurries.
Tuesday
A mix of sun and cloud with moderate to strong westerly winds. Light to moderate snowfall. Freezing level below valley bottom. Alpine highs of -20 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Wind slabs are most reactive during their formation.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Wind Slabs
Wind slabs formed earlier in the week may still be reactive to human triggers. Small but reactive new wind slabs are likely form with snowfall overnight Saturday and into Sunday. Expect to find wind loading on all aspects as winds switch from north to southwest. Slabs may be poorly bonded to the crust below.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of facets and a crust sits 40-70 cm deep in the snowpack. This layer is most likely to be found in sheltered and shaded locations.
Small avalanches or large cornice falls could step down to this layer resulting in large, consequential avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 18th, 2022 4:00PM
