Avalanche Forecast
Regions: Boundary, East Stikine, Kispiox, Ningunsaw, Northwest Coastal, Northwest Inland, Stewart, West Stikine.
Avalanche danger will decrease as temperatures cool but wind slabs remain triggerable at upper elevations.
Be sure to verify conditions by making observations as you travel.
Confidence
Moderate
Avalanche Summary
A very large natural avalanche cycle, size 2.5-3.5 was observed this week, with the most recent occurrence near Ningunsaw on Friday. These large avalanches included a combination of fresh wind slabs and persistent slabs failing on buried weak layers. Most were triggered in alpine start zones, entrained wet snow and ran far, many to valley bottom.
By Friday, most avalanche activity was trending smaller; size 1 rider-triggered wind slabs on north to east aspects.
Snowpack Summary
A moist upper snowpack up to 1800 m is refreezing into a crust as temperatures cool. In the alpine, overlying dry wind slabs may slow the refreeze.
Various layers formed in January are now buried 50-100 cm deep. Up to 1600 m this presents as a thick crust, and at higher elevations, facets, sometimes in combination with surface hoar. Large avalanches ran on these layers during the height of the recent warm, wet storm. It is expected that they will strengthen as temperatures drop.
Below treeline, the majority of the snowpack is rain-soaked and starting to refreeze. It diminishes rapidly to dirt below 500 m.
Weather Summary
Friday night
Partly cloudy with up to 5 cm of snow. Southwest ridgetop wind 30-40 km/h. Freezing level at valley bottom. Treeline low around -11 °C. Freezing level drops to valley bottom.
Saturday
Mostly sunny. West ridgetop wind 30-40 km/h. Treeline temperature around -10°C.
Sunday
A mix of sun and cloud. Northwest ridgetop wind 10-20 km/h. Treeline temperature around -8 °C.
Monday
Sunny. Northeast ridgetop wind 20-30 km/h. Treeline temperature around -10 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Make observations and assess conditions continually as you travel.
Avalanche Problems
Wind Slabs
Wind slabs may be triggerable at upper elevations where moderate winds are transporting dry snow into leeward terrain features. Cornices have grown large recently.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Persistent Slabs
Several weak layers buried between late December and mid-January are still a concern in this forecast area. Calmer, cooler weather is making them less reactive, but they might not really lock up until the weekend when it's much colder.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2.5 - 3.5