Avalanche Forecast
Issued: Feb 5th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
bchristie,
Avalanche Canada
Choose terrain that is sheltered from the wind. In the last few days, riders have triggered wind slab avalanches below ridgecrests, and in crossloaded gullies.
Check out this MIN report from Crowsnest Pass. It's a great example of where the wind slab problem can be found.
Summary
Confidence
Avalanche Summary
On Friday, a large (size 2), rider triggered, windslab avalanche was reported south of Crowsnest Pass. It occured in an open, cross-loaded feature below tree line on a north facing slope.
On Saturday, in neighboring Waterton National park, a similar but smaller (size 1.5) rider triggered avalanche occured on a southeast facing slope below treeline.
Small (size 1) isolated pockets of wind slabs continue to be triggered by riders in lee terrain features, especially when there is a hard sliding surface underneath. Wind slabs may linger directly lee of ridges at high elevations. See this MIN post for an example.
Please continue to share any observations or photos on the Mountain Information Network.
Snowpack Summary
5 to 10 cm of recent snow coupled with moderate to strong southwest winds has built wind slabs in lee and crossloaded features at alpine and treeline elevations, and in open features below treeline. A melt-freeze crust can be found at 2100 m and below at variable depths, on the surface on windward slopes, and buried 15 to 20 cm in lees. Wind slabs may be more reactive where they sit on this crust.
The middle of the snowpack is consolidated. Weak faceted grains exist near the base of the snowpack.
The average snowpack depth is 120 cm. Up to 200 cm can be found in wind-loaded areas.
Weather Summary
Sunday Night
Clearing overnight. No new snow expected. Moderate southwest ridgetop wind, trending to strong at higher elevations. Treeline temperature -3 °C, freezing level rising to 1700 m.
Monday
Mostly sunny, increasing cloud in the afternoon. No new snow expected. Moderate to strong northwest ridgetop wind. Treeline temperatures -5 °C, freezing level 1700 m.
Tuesday
Mostly cloudy. Possible trace of snow expected. Strong southwest ridgetop wind. Treeline temperatures -4 °C, freezing level 1700 m.
Wednesday
Mostly cloudy. 2-6 cm of snow expected. Possibly more in the far south of the region, depending on the track of the storm. Moderate west ridgetop wind. Treeline temperatures around -7 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Approach lee and cross-loaded slopes with caution.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
Problems
Wind Slabs
Recent snow and moderate winds have built new wind slabs over older wind slabs that may still be reactive. Expect these slabs to be most reactive in leeward terrain like ridgetops and cross-loaded features, and where a firm bed surface exists.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 6th, 2023 4:00PM
