Avalanche Forecast
Regions: Northwest Inland.
Certain slopes have potential for large persistent slab avalanches and even brief periods of exposure to the strengthening February sun may have a destabilizing affect. Carefully evaluate the snowpack and terrain before committing to avalanche terrain.
Confidence
Low - Uncertainty is due to the extreme variability of wind effect on the snowpack. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
We’re moving into a period of high winds with dribs/drabs of precipitation.
SATURDAY NIGHT: Freezing level at valley bottom, strong northwest wind, no significant precipitation expected.
SUNDAY: Broken cloud cover, freezing level around 500 m, strong west/northwest wind, trace of snow possible.
MONDAY: Broken cloud cover, freezing level around 500 m, strong west/northwest wind, trace of snow possible.
TUESDAY: Overcast, freezing level around 1000 m, strong west/southwest wind, trace of snow possible.
Avalanche Summary
On Friday some touchy wind slabs were observed, check out the details here. Isolated wind slabs and dry loose avalanches to size two were also reported on northerly aspects. A few natural very large (size 3) avalanches were observed in alpine features in the central portion of the region over the last few days.
Some very large persistent avalanches have been reported over the past week. A size 3 avalanche was triggered by a snowmobiler in the Seaton area on Monday (northeast slope at 1800 m) and a size 3.5 avalanche was remotely triggered by a large snow machine near Kispiox on Saturday (southeast slope at 1700 m). Then on Wednesday, several size 2-3 avalanches were naturally triggered due to strong wind and mild temperatures. These avalanches have ran on both buried surface hoar layers and crust/facets at the bottom of the snowpack.
Some smaller (size 1) wind slabs were also triggered by riders on Wednesday.
Snowpack Summary
Open terrain has been heavily affected by strong wind from the west. Crusts can be found on the surface up to roughly 1200 m and on open south-facing slopes. Some areas continue to have issues with weak layers that formed during cold weather in January. Depending on location these layers may be composed of soft facets or surface hoar and are typically are buried 60-120 cm below the surface. Crust/facet layers also lurk at the base of the snowpack, especially in shallower (eastern) areas. The most recent signs of instability with these deeper layers have been around Hazelton and Kispiox, but persistent weak layers could be a problem on slopes anywhere in the region.Â
Terrain and Travel
- Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Be alert to conditions that change with elevation and sun exposure.
Avalanche Problems
Persistent Slabs
Previous storms have agitated buried weak layers, resulting in some very large persistent slab avalanches. Although these avalanches are only possible in isolated locations, the consequences are severe. Recent areas of concern have been around Kispiox and Hazelton, but any large steep slope should be approached with caution.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 2.5 - 3.5
Wind Slabs
Recent storm snow is gradually gaining strength, but may remain reactive on steep wind loaded and sun-exposed slopes. Watch for the formation of fresh wind slabs as strong northwest winds begin to blow Sunday.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2