Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Feb 19th, 2023–Feb 20th, 2023

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Northwest Coastal, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson, Ningunsaw.

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.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.