Avalanche Forecast
Issued: Dec 22nd, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
jleblanc,
Avalanche Canada
The current storm will ease off Thursday morning. In areas where there is more than 30 cm new snow, increase the danger rating to HIGH.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain.
Weather Forecast
A low-pressure system over the Gulf of Alaska continues southwards, bringing moderate snow until Thursday evening. Arctic air will return late Thursday night, with bitterly cold and drier conditions for the weekend.
WEDNESDAY NIGHT: Snow 10-15 cm / Strong southerly wind / Low of -7 at 2000 m.
THURSDAY: Flurries 5 cm / Moderate west wind / High of -14 at 2000 m.
FRIDAY: Cloudy / Light southwest wind / High of -18 at 2000 m.
SATURDAY: Cloudy / Light southwest wind / High of -22 at 2000 m.
Avalanche Summary
Few observations were reported Wednesday due to poor visibility, but we suspected that natural avalanches occurred in the alpine. Natural dry loose avalanches were reported out of steep terrain (size 1) in treeline and below treeline.Â
If you go out in the mountains, please consider filling out a Mountain Information Network report.
Snowpack Summary
By the end of this storm, 25-40 cm of very light snow will have formed touchy soft slabs at all elevations/aspects. Recent strong alpine wind has also created firm wind slabs in alpine and open areas at treeline. Prior to this storm, cold temperature in the valley was prone to develop weak surface snow grains (surface hoar) in sheltered areas at treeline and below.
A concerning facet/crust layer, developed in early December, is now buried between 60-100 cm down. This layer generally exists below 1800 m and is most concerning in the area west of Blue River. In some places, the crust starts to decompose and show sporadic test results.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Storm Slabs
By Thursday morning, snow storm (25-40 cm) will have created touchy storm slabs at all elevations, especially behind lee features. These soft slabs will be easily triggered by riders, especially in wind-affected areas. The strong southwesterly flow associated with the storm means lots of heavy snow in the favoured slopes such as the south east part of the region.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A weak layer of facets can be found above a crust from early December, which is now down 80 to 150 cm and most concerning in the terrain West of Blue River at the treeline elevation. Although this persistent weak layer showed sporadic and various test results, keep in mind that the incoming storm may increase the likelihood of triggering it.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 23rd, 2021 4:00PM
