Avalanche Forecast
Issued: Dec 12th, 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.
swerner,
Avalanche Canada
Reduce your exposure to avalanche terrain if the temperature is above 0°C. Choose conservative terrain, weak layers in the mid and lower snowpack remain primed for human triggering.
Summary
Confidence
Moderate
Avalanche Summary
On Tuesday, explosive control continued to produce numerous deep persistent slab avalanches up to size 2 and above 2300 m. These slabs failed in the basal facets and a surface hoar melt freeze crust interface.
Natural avalanche activity has tapered since the storm, but with forecast warming, human-triggered avalanches remain likely at treeline and above.
Snowpack Summary
The recent 30 cm of storm snow has likely been redistributed into deeper deposits on north and east-facing slopes at higher elevations. This sits over a rain crust that has been observed up to 1900 m near Golden and 2200 m near Invermere.
A concerning layer of surface hoar is now buried 40-70 cm deep.
The middle and base of the snowpack holds large, weak snow crystals. A hard crust may be found near the ground.
Treeline snowpack depths are variable and generally range between 60 and 100 cm. Snowpack tapers rapidly as you move lower in elevation.
Weather Summary
Tuesday night
Mainly clear. Alpine wind 10 to 20 km/h from the southeast. Treeline temperature around -5 C with an alpine temperature inversion in many areas, expected to last for 24 hours.
Wednesday
A mix of sun and cloud. Alpine wind 25 to 35 km/h from the southeast. Treeline temperatures are around -8 C . Alpine temperatures are near +2 C with a weak temperature inversion. Freezing level 1500 m.
Thursday
Cloudy with snowfall, 5 - 10 cm. Alpine wind 10 to 20 km/h from the southwest. Treeline temperature around -9 C. Freezing level back to the valley bottom.
Friday
A mix of sun and cloud. Alpine winds are light from the south with alpine temperatures near -4 C. Freezing levels valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Extra caution for areas experiencing rapidly warming temperatures for the first time.
- Make conservative terrain choices and avoid overhead hazard.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
Problems
Wind Slabs
Recent winds have built reactive wind slabs in north and east-facing terrain features.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Surface hoar is most likely to be found at treeline elevations, and most triggerable where the rain crust (40-60 cm deep) disappears
Weak facets sit at the base of the snowpack, recent avalanches have failed on or stepped down to this layer
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 13th, 2023 4:00PM
