Avalanche Forecast
Regions: Boundary, East Stikine, Kispiox, Ningunsaw, Northwest Coastal, Northwest Inland, Stewart, West Stikine.
Sun, warm temperatures, and a complex snowpack are causing multiple avalanche problems. Very dangerous avalanche conditions are expected on Wednesday.
Confidence
Moderate
Avalanche Summary
On Monday, several natural persistent slab avalanches were reported up to size 3, several of which failed on the weak layer from early March. Some of these were triggered by cornice failures, and two were remotely triggered from up to 100 m away. Some natural wind slab avalanches were also observed.
On Sunday, a size 2 avalanche was rider-triggered on a northwest aspect in the alpine. This avalanche was believed to have occurred on the February drought layer.
Snowpack Summary
50-100 cm of recent snow has been redistributed by variable winds. This snow fell on previously wind-affected surfaces and crusts on steep south-facing terrain.
Three layers of concern currently exist in the upper-mid snowpack. Surface hoar that formed in mid-March can be found 65-85 cm below the snow surface. Below this, another layer of surface hoar that formed in early March can be found at a depth of 90-125 cm. Additionally, a layer of facets, surface hoar, and/or a crust from mid-February is buried 115-195 cm deep.
The remainder of the snowpack is well consolidated, and there are no current concerns.
Weather Summary
Tuesday Night
Mostly cloudy. 10 to 20 km/h southwest ridgetop wind. Treeline temperature -2 °C.
Wednesday
Mostly sunny. 20 to 30 km/h northeast ridgetop wind. Treeline temperature 0 °C. Freezing levels 1400 m.
Thursday
Mostly sunny. 20 to 40 km/h northeast ridgetop wind. Treeline temperature -1 °C. Freezing levels 1200 m.
Friday
Mostly sunny. 30 to 50 km/h east ridgetop wind. Treeline temperature -3 °C. Freezing levels 1000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, sun-exposed slopes when the air temperature is warm or when solar radiation is strong.
- Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Cornice failures could trigger large and destructive avalanches.
- Recent wind has varied in direction, so watch for wind slabs on all aspects.
Avalanche Problems
Persistent Slabs
Deeply buried weak layers are expected to become reactive with mild temperatures and sun, and very large natural avalanches should be expected on Wednesday.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 2 - 3.5
Loose Wet
Natural wet loose avalanches are expected from steep, sun-exposed slopes.
Cornices are also expected to become weak with mild temperatures and sun, and natural cornice failures are possible.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2
Wind Slabs
Recently formed wind slabs are expected to remain reactive, and human-triggering remains possible.
Cornices are also expected to become weak with mild temperatures and sun, and natural cornice failures are possible.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2