Avalanche Forecast
Issued: Dec 29th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
jleblanc,
Avalanche Canada
Persistent slab avalanches remain a concern anywhere the snowpack is thin and/or variable.
Keep up good travel habits and cautious route-finding.
Summary
Confidence
Avalanche Summary
On Friday, very large persistent slabs were naturally triggered (up to size 3) near Blackcomb Glacier and Whistler, with wide propagation from shallow rocky alpine northern slope. On Thursday, explosive control triggered numerous large storm slabs and cornice falls (size 2) and very large persistent slabs (size 2.5), some being remote-triggered. These avalanches involved up to 100-120 cm deep persistent weak layers that resulted in wide propagations.
Snowpack Summary
The snow surface is moist up to 2000 m where the recent 15-30 cm storm snow is rapidly settling due to warm temperatures on Friday. Between 50 and 100 cm of soft snow and heavily wind-affected snow overlies a layer of poorly bonded crusts and surface hoar. These have shown sensitivity to human triggers and snowpack tests recently, as well as recent natural and remote triggering avalanche activity. The lower snowpack is strong and bonded, and total snow depths remain below average.
Weather Summary
Friday Night
Cloudy with up to 5-10 cm of snow, alpine wind south 30 to 50 km/h, treeline temperature around 0 °C, freezing level lowering to 1600 m.
Saturday
Cloudy with 10-15 cm of snow, alpine wind south 50 to 70 km/h, treeline temperature around 0 °C, freezing level around 1600 m.
Sunday
Cloudy with isolated flurries, 1-3 cm of snow, alpine wind south 20 km/h, treeline temperature around -1 °C, freezing level around 1200 m.
Monday
Mostly sunny, no precipitation, alpine wind southwest 20 to 40 km/h, treeline temperature around -3 °C, freezing level at valley botom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
Problems
Wind Slabs
Fresh developing wind slabs will likely be reactive to human triggering. If triggered, wind slabs avalanches may step down to deeper layers resulting in larger than expected avalanches.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Avalanches could be bigger than expected, as some recent avalanches have propagated widely on 50 to 100 cm deep crust and surface hoar layers. Be especially cautious anywhere the snowpack is thin and/or variable.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 30th, 2023 4:00PM
