Avalanche Forecast
Issued: Jan 23rd, 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.
trettie,
Avalanche Canada
Avoid avalanche terrain, dangerous avalanche conditions exist in this region.
A fatal avalanche incident occurred south of Valemont on Saturday.
Summary
Confidence
Avalanche Summary
On Saturday a serious avalanche Incident occurred, 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.
Rider triggered avalanches continue to Occur in this region. This MIN describes a close call on Saturday.
Over the past week, there have been numerous reports of large human-triggered avalanches on both a 50 cm deep surface hoar layer in the middle of the snowpack and weak facets at the bottom of the snowpack. See photos of some of these avalanches here and here. A very large deep persistent slab avalanche (size 3) occurred naturally in alpine terrain in the western Cariboos on Jan 18.
All of these very large avalanches occurred at upper treeline/lower alpine. Avalanches like these are most likely to be triggered on steep, shallow and previously undisturbed slopes.
Snowpack Summary
New snow continues to gradually accumulate. Westerly winds will continue to affect exposed terrain and form wind slabs near ridgetops. 20 to 60cm of recent snowfall sits above a layer of surface hoar as well as a sun crust on steep solar aspects. Below 1600 m, recent snow is accumulating above a rain crust.
A prominent layer of buried surface hoar can be found roughly 40 to 80cm deep. It has shown ongoing signs of instability in the Valemount area, and could potentially be problematic throughout the Cariboos and Northern Monashees. The bottom of the snowpack is made up of large weak facets buried in late November, which has caused a deep persistent slab problem across much of interior BC.
Weather Summary
Monday Night
Cloudy with up to 15cm of new snow expected. Strong northwest wind and a low of -7 at 1800m.
Tuesday
Mostly cloudy with up to 10cm of new snow expected. Moderate to strong northwest winds and freezing levels rising to 1200m, high of -3 at 1800m.
Wednesday
A mix of sun and cloud with flurries bringing a few centimeters of new snow. Strong northwest winds and a high of -4 at 1800m.
Thursday
Cloudy with up to 5cm of new snow expected. Strong northwest winds and freezing levels rising to 1500m.
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.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- 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 reactive 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 travelling below steep slopes.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
New snow and west winds are expected to form fresh, reactive storm slabs that will be deepest in wind-loaded terrain at upper elevations. Reports suggest that the new snow overlies surface hoar in some areas. We'd be particularly suspect of sheltered areas at treeline where this weak layer is most likely to be preserved.
Keep in mind the very real potential of these slabs stepping down to deeper instabilities creating large and consequential avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A reactive surface hoar layer is found 40 to 70 cm deep throughout the region. Be especially cautious around steep convex openings at treeline and below. Remote triggering is also a concern for this layer.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 24th, 2023 4:00PM
