Avalanche Forecast

Archived

Apr 11th, 2023–Apr 12th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

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

South Coast, Powell River, North Shore, Sasquatch, Sasquatch, Tetrahedron.

Don't let good weather lure you into dangerous terrain.

Dry storm snow may be seeing its first test of strong sun, and avalanche danger could increase rapidly.

Confidence

Moderate

Avalanche Summary

Observations are limited at this time of year, but we suspected a natural avalanche cycle occurred last weekend with heavy loading from snow, wind and rain.

Looking forward to Wednesday, strong solar input has the potential to rapidly destabilize the dry surface snow. Back off steep solar slopes during periods of strong sun.

Snowpack Summary

Below 1000 meters, a thick crust exists on or near the surface. Above this elevation, 20-50 cm of dry snow has accumulated above a melt-freeze crust that extends to at least 1800 meters. At treeline and above, recent storm snow has been blown into wind slabs on west through east aspects. Below the new snow is a strong, well-settled snowpack.

Weather Summary

Tuesday night

Mainly clear. Alpine temperatures drop to a low of -2 °C. Ridge wind northwest 10-25 km/h. Freezing level drops to 700 metres.

Wednesday

Sunny with cloudy periods. Alpine temperatures reach a high of 3 °C. Ridge wind northwest 10-25 km/h. Freezing level rises to 1400 metres.

Thursday

A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of 0 °C. Ridge wind light from the southwest. Freezing level rises to 1100 metres.

Friday

A mix of sun and cloud. Alpine temperatures reach a high of -1 °C. Ridge wind light from the south. Freezing level rises to 900 metres.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be alert to conditions that change with elevation and sun exposure.
Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
Use ridges or ribs to avoid areas of wind loaded snow.
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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.