Avalanche Forecast
Regions: Kootenay Boundary.
Warming temperatures and periods of sun will likely help keep storm slabs reactive. Avoid terrain traps and use caution around wind loaded features and convexities in the alpine and upper treeline.
Confidence
High -
Weather Forecast
Wednesday night: Cloudy periods. Moderate northwest wind. Freezing level 1000 m.
Thursday: Mostly cloudy with isolated flurries early in the morning. Moderate west wind. Freezing level 1500 m.
Friday: Mix of sun and cloud. Light to moderate southwest wind. Freezing level 2000 m.
Saturday: Up to 5 cm new snow. Moderate southwest wind. Freezing level 1400 m.
Avalanche Summary
On Tuesday, size 1.5-2 storm slabs were reactive to skier traffic and solar input on convex features. A few small loose wet avalanches ran on steep solar features. A couple of skier triggered wind slab avalanches size 2-2.5 were reported on reloaded crust bed surfaces on northeast aspects just below ridgetop.
On Sunday and Monday, numerous natural, explosive, skier triggered, and remotely triggered storm slab avalanches were observed size 1-2 on all aspects at alpine and upper treeline elevations.
Snowpack Summary
15-30 cm of recent snow is settling over a layer of surface facets, surface hoar in sheltered shady aspects or sun crusts on solar aspects. Warming temperatures and the sun are speeding up settlement in the slab and keeping things touchy on the recent storm interface. In the alpine and exposed treeline, recent snow has been redistributed by strong southwest to northwest wind, loading deep and reactive deposits into lee features.
An older layer of surface hoar now sits 30-50 cm deep. This weak layer produced significant avalanche activity focused in the east of the region prior to the last storm. While it is likely bonding over time, there is uncertainty around remnant reactivity. The remainder of the snowpack is well settled.
Terrain and Travel
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Avalanche Problems
Storm Slabs
Storm slabs are expected to remain sensitive to human triggering, as warming temperatures and periods of sun promote rapid settlement of the slab over a weak interface. Storm slabs will be deepest and most reactive where wind has loaded lee terrain features in alpine and exposed treeline areas. Recent winds have varied in direction from south to northwest, wind loading a variety of aspects.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2
Persistent Slabs
An older layer of surface hoar now sits 30-50 cm deep. This weak layer produced significant avalanche activity focused in the east of the region prior to the last storm. While it is likely bonding over time, there is uncertainty around remnant reactivity. It has not been active in the recent avalanche cycle. If it remains triggerable, it will require large loads.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 2.5