Avalanche Forecast
Issued: Jan 22nd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Storm Slabs and Persistent Slabs.
zryan,
Avalanche Canada
This is a good time to take a big step back from avalanche terrain. New snow and wind are adding load to a weak and volatile snowpack. It's uncertain when the tipping point will be reached for large, destructive avalanches to occur and this uncertainty demands a conservative approach and low-consequence terrain selection.
Summary
Confidence
Avalanche Summary
On Saturday In the neighbouring region to the south, a serious avalanche, which resulted 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.
Looking forward to this week, reactive storm slabs are expected to form but concern for large natural and human-triggered avalanches is at the forefront of our minds. A series of incoming storms are adding load to shallow, weak snowpack with multiple layers of concern. It is uncertain when the "tipping point" for large destructive avalanches will be reached, but this uncertainty demands conservative and low-consequence terrain selection.
Snowpack Summary
Overnight snowfall will continue throughout the day bringing 10-25 cm of new snow. The accompanying northwest winds will affect wind-exposed terrain and build fresh wind slabs in lee terrain features. Below the new snow, a sun crust may be found on steep solar aspects.
Snowpack depths are shallower than normal, and several buried weak layers have been a concern over the past few weeks. One is a recently buried surface hoar layer found 30 to 60cm deep in sheltered terrain features at treeline and above. At this same depth, a crust exists on steep south-facing slopes. Another layer of facets, crust, and surface hoar was buried around Christmas and is now 50 to 90cm deep. Finally, a layer of large, weak facets buried in November is found near the bottom of the snowpack. This layer is likely most problematic in alpine terrain, where shallower avalanches could scrub down to these basal facets.
Weather Summary
Sunday night
Cloudy with increasing snowfall, 5-15 cm of accumulation. Alpine temperatures drop to a low of -10 C. Ridge wind northwest 40-60 km/h. Freezing level at valley bottom.
Monday
Mainly cloudy with continued snowfall, 5-15 cm of accumulation. Alpine temperatures rise to -7 C. Ridge wind northwest 45-70 km/h. Freezing level rises to 1100 m.
Tuesday
Cloudy with snowfall, 5-10 cm accumulation. Alpine temperatures reach a high of -6 C. Ridge wind northwest 40-60 km/h. Freezing level rises to 1100 m.
Wednesday
Mainly cloudy with snowfall, 5-15 cm of accumulation. Alpine temperatures reach a high of -1 C. Mostly light westerly ridge wind occasionally gusting to 35 km/h. Fre
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- 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 as wind and snowfall add load to a fragile snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
New snow and northwest winds are expected to form fresh storm slabs that will be deepest and most reactive in wind-loaded terrain at upper elevations.
Keep in mind the very real potential of these slabs stepping down to deeper instabilities creating large and consequential avalanches.
Aspects: All aspects.
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 traveling below steep slopes.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 23rd, 2023 4:00PM
