Avalanche Forecast
Regions: North Columbia.
Recently formed storm slabs are expected to remain reactive to human triggers on Sunday.
These slabs will be most reactive on wind-loaded slopes where the slabs are sitting on either a sun crust or a weak layer of surface hoar.
Confidence
Moderate - Uncertainty is due to whether buried persistent weak layers become active, triggering avalanches, with the arrival of the forecast weather.
Weather Forecast
SATURDAY NIGHT: Cloudy with flurries; 3-10 cm / Light southwest winds / Low of -6 / Freezing level valley bottom.
SUNDAY: Flurries; 5-10 cm, and another 5-10 cm overnight / Light west wind / High of 0 / Freezing level 1500 m.
MONDAY: Flurries; 5-10 cm / Moderate southwest wind / High of 1 / Freezing level 1600 m.
TUESDAY: Snow; 15-20 cm / Moderate southwest wind / High of 1 / Freezing level 1600 m.
Avalanche Summary
Numerous skier triggered storm slab avalanches up to size 1.5 were reported on Saturday. The storm slabs were most reactive were they were sitting on a sun crust or a weak layer of surface hoar.
Additionally, a size 2.5 naturally triggered wind slab avalanche was reported on a northeast aspect.
Snowpack Summary
10-15 cm of new snow and moderate southwest winds on Friday night formed fresh storm slabs that will be most reactive in wind affected terrain.
The 15-25 cm of recent snow is sitting on a variety of surfaces including hard wind affected snow, sun crusts on southerly slopes, and surface hoar on shady or sheltered slopes. Expect storm slabs to be most reactive where they are sitting on either a sun crust or surface hoar.
The late February persistent weak layer combination of crust, facets and surface hoar is down 30-40 cm. Reports suggest this layer is becoming less reactive in most areas.
Two persistent weak layers from mid February and late January are buried 50-120cm deep. No recent avalanches have been reported on these layers but they continue to produce the occasional notable result in snowpack tests.
The most likely triggers of these persistent weak layers are large triggers such as smaller avalanches in motion, cornices, or snowmobiles.
Terrain and Travel
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Be especially cautious as you transition into wind affected terrain.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
Avalanche Problems
Storm Slabs
10-15 cm of new snow and moderate southwest winds on Friday night formed fresh storm slabs that will be most reactive in wind affected terrain, especially where the recent snow is sitting on a weak layer of surface hoar.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1.5 - 2.5