Avalanche Forecast

Archived

Feb 24th, 2025–Feb 25th, 2025

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 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.

Regions

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

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

Confidence

Moderate

Avalanche Summary

Evidence of wet natural avalanche cycles was observed after Sunday's storm. Several storm slabs (up to size 3) were released with numerous stepping down to the late-Jan/early Feb persistent layers around 60 to 80 cm deep in the snowpack. This problem remains a serious concern on steep northerly slopes at treeline and above as the next storm brings more snowfalls.

Snowpack Summary

15 to 25 cm of new snow accumulated overnight Sunday along with strong to extreme winds, bringing storm totals to ~50 to 80 cm. These storm totals overlie problematic faceted snow, or surface hoar in sheltered terrain. In exposed terrain, a sun crust is present up to 1700 m while wind-affected surfaces exist at upper elevations.

A weak layer, buried at the end of January, is now 80 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. The last storm woke this layer up decisively and both natural avalanches and human triggering on this layer are a serious concern.

Weather Summary

Monday Night

Cloudy with 10 to 15 cm of new snow. 40 to 60 km/h southeast ridgetop wind. Treeline temperature stable around -4°C. Freezing level around 1200 m.

Tuesday

Cloudy with isolated flurries up to 5 cm of new snow. 10 to 20 km/h northwest ridgetop wind. Treeline temperature stable around -2°C. Freezing level around 1500 m.

Wednesday

Partly cloudy. 40 to 60 km/h southeast ridgetop wind. Treeline temperature stable around +4°C. Freezing level reaching to 2500 m.

Thursday

10 to 15 cm of new snow. 50 to 70 km/h southwesterly ridgetop wind. Treeline temperature 0°C. Freezing level lowering to 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
Storm slabs in motion may step down to deeply buried weak layers and result in very large 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.