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Avalanche Forecast

Archived

Feb 23rd, 2025–Feb 24th, 2025

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

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Powell River, Spearhead, Tantalus.

The parade of storms has woken up a nasty persistent slab and more snow is coming. The consequences of triggering an avalanche could be much higher than surface instabilities suggest.

Confidence

Moderate

Avalanche Summary

An increasing number of natural and controlled avalanches have been reported since the parade of storms began. Wind slabs and storm slabs to size 2 were not unexpected, however Saturday saw a marked increase in avalanches failing on or stepping down to the late-Jan/early Feb persistent layers around 60 cm deep (and counting) in the snowpack. This problem remains a serious concern as the next storm takes aim at the coast Sunday night.

Snowpack Summary

15 - 25 cm of new snow should accumulate overnight Sunday, bringing storm totals to ~50 - 80 cm, all of it affected by strong southerly winds. These storm totals overlie problematic faceted snow, or surface hoar in sheltered terrain. In exposed terrain, sun crust (an excellent bed surface for avalanches) or previously wind-affected snow are more likely.

A weak layer that was buried at the end of January is now 60 to 100 cm deep in the snowpack. This may present as a crust on sunny slopes, sugary facets in most places, and surface hoar in sheltered spots. Saturday's storm woke this layer up decisively and both natural avalanches and human triggering on this layer are a serious concern.

The snowpack below is strong.

Weather Summary

Sunday Night

Cloudy with snow showers bringing 15 - 25 cm of new snow, increasing with elevation, rain below about 1000 m. 30 to 50 km/h southwest ridgetop wind. Freezing level 1300 m.

Monday

Clearing over the day, clouding over in the afternoon. 20 to 50 km/h southeast ridgetop wind. Freezing level 1200 m - 1500 m.

Tuesday

A mix of sun and cloud after about 5 cm accumulation overnight. 5 - 15 km/h variable ridgetop wind. Freezing level 1200 m - 1600 m.

Wednesday

Becoming sunny. 30 - 50 km/h southeast ridgetop wind. Freezing level shooting to 2400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
  • Approach lee and cross-loaded slopes with caution.
  • Storm slabs in motion may step down to deeply buried weak layers and result in very large avalanches.
  • Even brief periods of direct sun could produce natural avalanches.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.