Avalanche Forecast

Archived

Mar 19th, 2022–Mar 20th, 2022

Alpine

Natural avalanches unlikely, human triggered possible.

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 possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Cariboos.

Avalanche danger is highest in the central and southern Cariboos. Conservative terrain choices are advised, buried weak layers still remain reactive on specific features.

Minimize exposure to south facing slopes during strong sunshine, avalanche danger can rise rapidly.

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

SATURDAY NIGHT: Flurries continue, around 5 cm of snow. Freezing levels drop to valley bottom. Moderate southwesterly winds.

SUNDAY: Mostly sunny with moderate southwest winds. Freezing levels reach 1200 m, alpine high of -4.

MONDAY: Scattered flurries with partly cloudy skies. Moderate southwest winds. Freezing levels reach 1700 m. Alpine high of +1

TUESDAY: Mostly cloudy with scattered flurries. Strong southwest winds. Freezing levels remain high, reaching 2000 m. Alpine highs around +4.

Avalanche Summary

On Friday, a rider triggered size 1.5 slab avalanche was reported on the buried surface hoar on a convex roll at treeline.

Avalanche activity has been tapering off over the week, with natural activity observed on Thursday. On Wednesday large remotely triggered avalanches were reported on north and south aspects with impressive propagation.

Small wet avalanches have been reported within the last 5 days, on all aspects below the freezing line and on sun affected slopes.

Snowpack Summary

Up to 70 cm of recent settling storm snow sits over a layer of weak surface hoar in sheltered and shaded terrain, and over a crust on south facing slopes. The new snow is bonding poorly to this old surface in some areas, producing large avalanches within the last 5 days, and reactive results on testing.

At higher elevations consistent southwest winds are creating deeper deposits on north through east facing features. Below 1500 m, moist snow or a melt-freeze crust likely exists from recent rain and warm temperatures.

The lower snowpack is generally well-settled and strong in most areas, with crust layers 50 to 100 cm deep.

Terrain and Travel

Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.

Problems

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.