Avalanche Forecast
Regions: Howson, Kitimat, Nass, Northwest Coastal, Rupert, Seven Sisters, Shames, Stewart, West Stikine.
The south of the region will be the hotspot for snowfall on Monday. Avalanche danger will increase throughout the day as heavy snowfall and strong northwest wind form increasingly large and reactive storm slabs.
Be prepared to dial back into more conservative terrain as new snow accumulates and avoid overhead exposure to large and fragile cornices.
Confidence
Moderate
Avalanche Summary
Stormy weather has limited observations in the past few days, but evidence of a natural storm and wind slab cycle has been observed throughout the region. One notable size 2.5 skier-remote storm slab was observed in the north of the region. This large avalanche was triggered from ~150 m away and had a crown depth of 100 cm.
Looking forward to Monday, we expect avalanche danger to increase throughout the day as heavy snowfall and wind form increasingly large and reactive storm slabs. A natural avalanche cycle can be expected and human-triggered storm slabs are likely.
Snowpack Summary
Up to 40 cm of new snow can be expected by the end of the day on Monday. This new snow will add to 60 cm of recent storm snow. New storm and wind slabs will form throughout the day on Monday. Large cornices will continue to grow.
Up to 80cm now sits over a layer of small surface hoar, facets and wind-affected surfaces. Below treeline, a new crust could exist up to 1000m.
A layer of facets and a crust from late January can be found down 100 to 200cm. Below this layer, the snowpack is generally well-settled and right-side up.
Weather Summary
Sunday night
Flurries, 5-10 cm of accumulation. Alpine temperatures drop to a low of -3 °C. Ridge wind southwest 20 km/h gusting to 50 km/h. Freezing level 500 metres.
Monday
Cloudy with snowfall, heavy at times, 15-30 cm of accumulation. Alpine temperatures reach a high of -2 °C. Ridge wind southwest 20-30 km/h. Freezing level 600 metres.
Tuesday
Mainly sunny. Alpine temperatures reach a high of -7 °C. Ridge wind northeast 30-45 km/h. Freezing level at valley bottom.
Wednesday
Sunny with cloudy periods. Alpine temperatures reach a high of -13 °C. Ridge wind northeast 20-40 km/h. Freezing level at valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of heavy snowfall.
- Storm slab size and sensitivity to triggering will likely increase through the day.
- As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Avalanche Problems
Storm Slabs
Storm slabs will increase in size and reactivity throughout the day as snowfall intensifies. Strong northwest winds will form deeper deposits in wind-exposed lee areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1.5 - 3
Cornices
This week's 60-80 cm of new snow and westerly winds have built large fragile cornices along ridgelines. Avoid overhead exposure and give cornices a wide berth when travelling on ridges.
Aspects: North, North East, East, South East, South, South West, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1.5 - 3