Avalanche Forecast
Issued: Dec 12th, 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
Take careful steps as you venture into the backcountry, and back off if you find signs of instability.
Natural avalanche activity should taper off, but storm slabs remain reactive to riders.
Summary
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
We are heading into a less stormy period with cooler temperatures, but light to moderate snowfall continues.
SUNDAY NIGHT: Overcast. Possible trace of snow. Moderate to strong southwest wind. Freezing level dropping.Â
MONDAY: Mostly cloudy with possible clear periods. 3-7 cm of snow expected. Light to moderate southeast wind, trending towards strong southwest at higher elevations. Freezing level at valley bottom in the morning, rising to 750m through the day.
TUESDAY: Mostly cloudy. 5-15 of snow expected overnight, and another 2-5cm through the day. Light southwest wind, trending to moderate west at higher elevations. Alpine low around -12 C.
WEDNESDAY: Mostly cloudy. Possible trace of snow. Light southwest wind trending to strong westerly at higher elevations. Warming through the day, alpine high around -10 C.
Avalanche Summary
Expect storm slabs to remain reactive to riders as the heavy snowfall eases. Light snowfall continues, and the snowpack still needs time to adjust to the new load.Â
Reports from Saturday and Sunday indicate that the storm slab was touchy. Avalanche control with explosives produced many avalanches size 1.5-2, with one size 2.5 reported.Â
On Saturday, there was a report of avalanches being remotely triggered by skiers in the backcountry.Â
Another backcountry rider reported whumpfing and shooting cracks in 30-60cm deep slabs around treeline, causing their group to retreat to wind sheltered terrain.
Snowpack Summary
Storm slabs remain at the top of the snowpack, and snowfall has eased, but winds continue. There is a lot of new snow available for wind transport. Expect to find deeper and more reactive slabs in leeward slopes. Â
Below 2400m, expect to find a thick (20 cm or more) melt freeze crust on all aspects down 50-100 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
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
An avalanche that starts in the storm snow has the potential to step down to the Late November/Early December rain crust.
This crust is widespread across the province, and many operations have been watching it for signs of reactivity as the load on top of it increases. It may also get more reactive as cold temperatures promote faceting above the crust.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 13th, 2021 4:00PM
