Avalanche Forecast
Issued: Dec 10th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
bchristie,
Avalanche Canada
Today is a good day to avoid avalanche terrain. Heavy snowfall, wind and warm temperatures are making avalanches very likely.
Snowfall is forecast to be the heaviest in the Lizard Range. If your area sees less than 30cm of snow through the day, reduce hazard to considerable.
Summary
Confidence
Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system. We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.
Weather Forecast
FRIDAY NIGHT: Overcast. 5-15 cm of snow expected. Strong to extreme southwest wind. Temperature rising in the alpine to warmer than -10.
SATURDAY: Overcast. Heavy snowfall. 30-60cm of snow expected through early Sunday morning. Strong to extreme southwest wind. Expect wind speed to increase drastically as you gain elevation. Freezing levels climb to between 1000 and 1500m.Â
SUNDAY: Mostly cloudy. 5-10cm of snow expected. Strong southwest wind. Freezing level around 1000m.Â
MONDAY: Mostly cloudy. 0-5cm of snow expected. Moderate to strong south to southwest wind. Freezing level back to valley bottom in the morning, rising through the day. Alpine high around -6.
Avalanche Summary
Expect natural and skier triggered avalanches to be likely if the weather forecast holds true.
Yesterday, avalanche control work continued to trigger wind slabs up to size 2.5.
On thursday, natural trigged storm slab avalanches were observed to size 2 near Fernie. Explosives and skiers in the same area also triggered storm slabs to size 2 yesterday, all failing on the melt freeze crust.Â
Over the last week natural and skier triggered slab avalanches have been reported in wind loaded features at treeline and above.Â
Note there are very few field observations this early in the season. If you venture out into the mountains, please share your observations and/or photos on the Mountain Information Network!
Snowpack Summary
Over the course of the day, 30-60cm of new snow that is falling with strong wind and warming temperatures has the potential to create a reactive, upside-down snowpack.Â
Below 2400m, expect to find a thick and supportive melt freeze crust on all aspects down 40-80 cm.Â
The snowpack holds several early season crusts about 20-30cm above the ground. Last week's heavy rain saturated the snowpack and has begun to break down this crust at treeline and below, creating a cohesive lower snowpack.
Snowpack depths range from 40-130 cm at treeline elevations. The snowpack tapers quickly below 1800m.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of a buried crust.
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
Underneath the new storm snow, there are lingering wind slabs that were bonding poorly to the icy crust below. An avalanche that starts in the storm snow has the potential to step down to these wind slabs. These wind slabs were most prominent at treeline and in the alpine on northwest through south aspects.
If you are unsure where the old wind slabs are lurking, then assume any storm slab avalanche that starts has the potential to get bigger than expected.
Expect storm slabs to be the deepest and most reactive in the Lizard Range. That area is expected to receive significantly more snow than the rest of the region.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 11th, 2021 4:00PM
