Avalanche Forecast
Issued: Jan 7th, 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.
dsaly,
Avalanche Canada
Recently formed windslabs may be easily triggered by skiers. Be especially mindful around ridges and steep, convex terrain.
Summary
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
Friday night: Snowfall 5-10 cm. Moderate SW ridgetop wind. Treeline low around -18 °C.
Saturday: Cloudy with isolated flurries, up to 5 cm. Strong to extreme SW to NW ridgetop wind. Treeline high around -8 °C.Â
Sunday: Sunny. Moderate SW wind switching NW. Increasing temperatures with a treeline high around -4 °C.
Monday: Sunny. Moderate SW wind. Treeline high around -2 °C.
Avalanche Summary
On Wednesday, explosive control work produced numerous loose dry and thin wind slab avalanches in alpine terrain. These avalanches started small but entrained mass in tracks, growing to size 2.5 and running up to 1300m. It is worthy to note that no deep slabs were triggered.
On Monday and Tuesday, natural, explosive and skier triggered storm slabs and loose dry avalanches size 1-2 were observed out of NE-SE aspects in the alpine.
The persistent slab problem has produced sporadic and spotty activity in the South Rockies and nearby regions. The most recent avalanche in the region was last Friday, when explosives triggered a size 2.5 wind slab avalanche that stepped down to the persistent slab layer on a SE aspect near treeline. Otherwise, persistent slab activity has not been observed in the region since before Christmas. A few recent notables from surrounding regions feature in our latest blog, Photos of recent persistent slab avalanches in the southern interior.
Snowpack Summary
10-40 cm snow accumulated through Friday. Strong winds during the storm developed more reactive deposits around convex and lee features. An accumulated total of 30-60 cm of new and recent snow now sits over a hard, faceted snow surface from the recent cold conditions, which may make for a weak bond at this interface.
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now typically down 70-130 cm. The most recent avalanche on this layer was a week ago but sporadic activity has been observed in neighboring regions in the past week. This layer has created a tricky low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.
Terrain and Travel
- Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
- 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.
Problems
Wind Slabs
Strong to extreme winds have redistributed fresh snow. More reactive deposits will be found on convex rolls and leeward terrain. The new and recent snow may overlie a weak interface which could result in deeper and touchier than expected slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A persistent slab problem formed by a crust down 70-150 cm has created a low likelihood, high consequence scenario that is difficult to forecast. Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 8th, 2022 4:00PM
