Avalanche Forecast
Issued: Dec 30th, 2021 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
JSmith,
Avalanche Canada
Conditions in this region are "Tricky" right now. Numerous very large persistent slab avalanches failing on a crust have been reported in recent days.
Check out the latest Forecasters' Blog for tips on managing the ongoing Persistent Slab problem in this region.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
THURSDAY NIGHT: Partly cloudy / Light northwest wind / Low of -25
FRIDAY: Sunny / Light northwest wind / High of -17
SATURDAY: Mix of sun and cloud / Moderate northwest wind / High of -17
SUNDAY: Cloudy with flurries; 3-5 cm / Strong southwest wind / High of -12
Avalanche Summary
A naturally triggered size 3 persistent slab was reported near Rossland on Wednesday. See MIN.Â
A skier triggered size 2 storm slab which stepped-down to the early December crust was also reported at Kootenay Pass on Wednesday.
Explosive control work at Kootenay Pass on Tuesday produced numerous persistent slab avalanches failing on the early December crust, up to size 3.5.
A rider triggered size 2.5 persistent slab avalanche involving several riders was reported near Nelson on Monday. The avalanche occurred on a southeast aspect at approximately 1900 m. It failed on the crust formed in early December. The treeline slope was heavily wind effected and the rider triggered the avalanche from a thin spot where the layer was only around 60 cm deep. There is a MIN report of the incident.
Snowpack Summary
Recent storm totals reached over 100 cm. There is a lot of snow available for transport which will form fresh wind slabs when wind speeds increase to moderate.
A crust formed in early December has been responsible for numerous very large persistent slab avalanches in recent days. The depth of the crust ranges widely from 50-150 cm and is most likely to be triggered in wind affected terrain below ridgetops.Â
Nearly all of the recent avalanches have been triggered from shallow spots in the snowpack where the crust is less than 100 cm deep. Avoid steep, rocky slopes with a shallow or thin to thick snowpack.
The lower snowpack is composed of several early-season crusts. Snow depths at treeline average 150-300 cm.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
Problems
Persistent Slabs
A persistent slab problem formed by a crust down 50-150 cm has created a low likelihood, high consequence scenario that is difficult to forecast. This layer is most likely to be triggered in windy areas where the depth of the snowpack is highly variable.
Avoid likely trigger spots such as steep, rocky or convex slopes with a shallow or thin to thick snowpack.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Expect the storm slabs formed from last weekend's storm to be most reactive in wind affected terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 31st, 2021 3:00PM
