Avalanche Forecast
Issued: Jan 20th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
cgarritty,
Avalanche Canada
Watch for new and recent wind slabs in unusual places after rapid shifts between northwest and southwest winds. Surface instabilities aside, the basal snowpack continues to demand thoughtful terrain selection to avoid triggering a very large avalanche. Keep up the safe group management decisions and avoiding shallow rocky start zones.
Summary
Confidence
Moderate
Avalanche Summary
Explosives control in the Fernie area yielded storm slabs to size 2 (large) on Thursday, with depths of up to 15 cm and propagations up to 50 m wide. This is a good indication of surface instabilities you may find lingering in in leeward terrain features near ridgecrests on Saturday.
On Tuesday and Wednesday, more human-triggered wind slabs up to size 1 were reported at treeline and above.
Snowpack Summary
Roughly 10 cm of recent snow has been getting moved into small wind slabs in exposed areas and otherwise blending into older wind-affected surfaces above 1800-2000 m and settling on a crust below this elevation.
A crust/facet layer (2-15 cm thick at TL elevation) is down 50-90 cm. Where it's thickest, it caps the settled and consolidated mid-snowpack.
Another crust/facet layer is down 70-150 cm. Below this crust, the basal snowpack is weak and faceted.
Weather Summary
Friday night
Mainly cloudy. Light southwest or northwest winds, more northerly with elevation.
Saturday
Increasing cloud with isolated flurries, increasing overnight. Moderate to strong southwest winds, increasing over the day. Treeline high temperatures around -6.
SundayCloudy with easing flurries and a variable trace to 10 cm of new snow, including overnight amounts. Light to moderate northwest winds. Treeline high temperatures around -6.
MondayCloudy with scattered flurries bringing less than 5 cm of new snow. Light to moderate southwest winds. Treeline high temperatures around -6.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
Problems
Wind Slabs
Elevated northwest winds have likely formed wind slabs on leeward slopes along ridgecrests at higher elevations. Expect any you encounter to remain reactive to human triggering on Saturday.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Faceted grains make up the basal snowpack and are gaining strength very slowly. Where supportive to riders, a melt-freeze crust may be providing a bridging effect, making it more difficult to trigger deeper layers. Any avalanche triggered this deep will likely be large and destructive.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 21st, 2023 4:00PM
