Avalanche Forecast
Regions: Purcells.
Be mindful of conditions that change with aspect and elevation, like transitioning from ridgetop into a steep north-facing slope below.
Confidence
Moderate - Uncertainty is due to difficult to forecast freezing levels.
Weather Forecast
Friday night: Unsettled in the wake of the cold front with isolated and localized flurries, 5-20 cm by morning along with moderate to strong southwest winds. Freezing level dropping to valley bottom, overnight low -9 C.
Saturday: Blustery with alpine flurries, up to 5 cm. Light southwest winds. Freezing level near valley bottom, ridgetop high -5 C.
Sunday: A mix of sun and cloud with isolated flurries, trace to 5 cm. Light west winds. Freezing level remaining near valley bottom, ridgetop high -3 C.
Monday: Overnight flurries bringing trace to 10 cm. Light west winds. Ridgetop high -4 C.
Avalanche Summary
A loose wet avalanche cycle from solar slopes began late Thursday afternoon. Explosives also triggered several size 1 wind slabs, all about 20 cm thick.
On Wednesday, a size 3 natural wind slab was observed on a northeast aspect at 2300 m.
Over the past few days ski cutting has produced wind slab avalanches up to size 1.5. These avalanches have generally been on north and east aspects in treeline terrain. Explosive control has produced storm and wind slab avalanches up to size 2.5 on all aspects at treeline and above in the western part of the region where more storm snow was recorded. Several small cornice falls have also been observed.
Snowpack Summary
A crust has formed on all aspects up to 2200m and mountain top on steep, solar slopes. Variable winds have impacted dry snow at upper elevations and formed thin wind slabs in lee features.
A thick rain crust with facets above from early December is buried around 150 cm deep. Large avalanches were naturally triggered on this layer during the last significant warming event in western terrain near the Bugaboos. Avalanche activity on this layer will become unlikely as the freezing level falls.
Terrain and Travel
- Avoid exposure to slopes that have cornices overhead.
- Dial back your terrain choices if you are seeing more than 20 cm of new snow.
- Wind slabs may be poorly bonded to the underlying crust.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Avalanche Problems
Wind Slabs
Wind slabs exist in exposed alpine terrain. Size and sensitivity to triggering could be greater where wind slabs have formed over a crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Cornices
Springtime cornices are large and capricious. Give them plenty of space traveling along ridges and avoid lingering below them.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 2.5