Avalanche Forecast
Issued: Jan 24th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Reactive wind slabs will continue to form in lee and cross-loaded areas, but our main concerns remain with several buried weak layers that continue to produce large human-triggered avalanches.
Adjust your goals to match conditions and stay disciplined in your terrain choices. Rather than ticking off objectives or seeking out fresh, untracked slopes enjoy the simplicity of riding lower-angled terrain and getting exercise outdoors while spending time with friends.
Summary
Confidence
Avalanche Summary
On Monday, a serious skier-triggered avalanche incident occurred in the Selkirks near Revelstoke. The avalanche was on an east aspect at 1900 m. It occurred on a steep, unsupported open slope below treeline and failed on a weak layer of surface hoar buried in early January. This large avalanche (size 2) had a crown depth of 50 cm. Details are still emerging about this event.
Numerous natural and human-triggered wind slabs were also observed on Sunday and Monday throughout the region. One of these avalanches in the south of the region resulted in a partial burial and details are still emerging about the severity of this event. These avalanches mainly occurred on east and northeast aspects in the alpine and treeline.
On Saturday in the neighbouring region to the north, a serious avalanche, resulting in a fatality, occurred in the Oasis riding area south of Valemont. The avalanche was on a north-northwest aspect at 2100 m. It was remotely triggered and ran on the November facets near the bottom of the snowpack. This large avalanche (size 2.5) had a depth of 80 to 120 cm. There were several other reports of human-triggered avalanches from nearby areas.
Large and highly consequential avalanche activity has been ongoing for several weeks and is likely to persist for some time. Your best defence at this time is to stay diligent in choosing conservative and low-consequence terrain. Stick to slopes that have been heavily trafficked throughout the winter and avoid venturing into untouched zones. Adjust your goals to match conditions. This is not a time to tick off objectives, but rather to enjoy lower-angled riding, get exercise, and spend time outdoors with friends. Stay disciplined and adjust your expectation for this winter.
Snowpack Summary
New snow continues to gradually accumulate. A layer of surface hoar may be found below 5-15cm of recent snowfall as well as a sun crust on steep solar aspects. Westerly winds will continue to affect exposed terrain and form wind slabs near ridge tops. At lower elevations, a rain crust exists down 10 to 40cm, with reported elevations extending up to 1700 m around Revelstoke and closer to 2000 m further south.
Two persistent weak layers in the middle of the snowpack may remain reactive to human triggering. They are both surface hoar layers that formed in early January and are typically found 40 to 90 cm deep throughout the region. There are also some deeper facet and surface hoar layers that formed in December, but recent snowpack observations suggest they are strengthening.
The bottom of the snowpack is made up of large weak facets buried in late November, which has caused an atypical deep persistent slab problem for this region.
Weather Summary
Tuesday night
Cloudy with isolated flurries, up to 5 cm of accumulation. Alpine temperatures rise to around -5 C. Ridge wind west 20-50 km/h. Freezing level 500-1000 m.
Wednesday
Mainly cloudy with isolated flurries. Alpine temperatures rise to -4 C. Ridge wind northwest 30-70 km/h. Freezing level rises to 1000 in the south and 1500 m further north.
Thursday
A mix of sun and cloud with flurries. Alpine temperatures remain elevated around -4 C. Ridge wind northwest 30-70 km/h. Freezing level 1000-1500 m.
Friday
Mainly cloudy with flurries, up to 5 cm of accumulation. Alpine temperatures drop to -8 C. Ridge wind west 25-40 km/h. Freezing level drops to 500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer has most recently been problematic in upper treeline/lower alpine elevations.
Avoid thin and rocky start zones where weak layers sit closer to the surface, riders are most likely to trigger an avalanche on this layer in steep, shallow previously undisturbed terrain or by first triggering a layer further up in the snowpack.
Remote triggering is a concern for this layer, avoid traveling below steep slopes.
The likelihood of avalanches will increase on slopes with active wind-loading.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Northwesterly winds will continue to form fresh wind slabs in the alpine and treeline.
Be aware that wind slabs could step down to deeper layers.
Aspects: North, North East, East, South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Numerous problematic weak layers exist in the top meter of the snowpack, with recent observations suggesting the most likely of these to trigger are surface hoar layers found 40 to 90cm deep. Be especially cautious around steep convex openings at treeline and below.
Remote triggering is a concern for this layer, avoid travelling below steep slopes.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 25th, 2023 4:00PM
