Avalanche Forecast

Archived

Apr 18th, 2023–Apr 19th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Spearhead, Tantalus, Sky Pilot.

Conservative terrain travel is recommended, as the storm snow may need some time to bond to the snowpack.

Confidence

Moderate

Avalanche Summary

Small to large (size 1 to 2) storm slab avalanches were triggered by riders, explosives, and naturally over the past couple days, generally being about 30 cm thick and primarily at alpine and treeline elevations. Some of them were triggered by small pieces of cornices failing.

We anticipate similar avalanches could be triggered by riders on Wednesday. Brief periods of sunny skies could also trigger small loose wet avalanches out of steep, rocky terrain on sun-exposed slopes.

Snowpack Summary

Around 5 to 10 cm of snow over the course of Wednesday will build on the 40 to 50 cm of snow that accumulated since the start of last weekend. The wind has been consistently strong from the south to southeast, likely forming wind slabs in lee terrain features on northerly slopes.

All this snow may sit on a weak layer of surface hoar crystals on sheltered and shaded treeline and alpine slopes. The snow overlies a hard melt-freeze crust on sun-exposed slopes and on all aspects below 1500 m.

The remainder of the snowpack is well-bonded.

Cornices are large and looming and continue to grow during this stormy weather.

Weather Summary

Tuesday Night

Cloudy with snowfall, accumulation 2 to 5 cm, 20 to 40 km/h southeast wind, treeline temperature -7 °C.

Wednesday

Cloudy with snowfall, accumulation 2 to 5 cm, 20 to 40 km/h south wind, treeline temperature -7 °C, freezing level 1200 m.

Thursday

Partly cloudy with isolated flurries, 10 to 20 km/h south wind, treeline temperature -6 °C, freezing level 1400 m.

Friday

Cloudy with snowfall, accumulation 5 cm, 20 to 40 km/h south wind, treeline temperature -5 °C, freezing level 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Carefully monitor the bond between the new snow and old surface.
Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Be especially cautious as you transition into wind affected terrain.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.
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.