Avalanche Forecast

Archived

Mar 28th, 2021–Mar 29th, 2021

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 possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Cariboos.

Strong winds shifting northwest overnight will continue to redistribute recent storm snow into deep slabs. Give the new snow time to settle and stabilize before pushing into bigger terrain. Crusty surfaces below treeline will make for low hazard but difficult travel conditions.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

Sunday night: Flurries bringing up to 5 cm. Moderate northwest wind. Freezing level dropping to valley bottom. Alpine temperature -15.

Monday: Mix of sun and cloud. Light to moderate northwest wind. Freezing level valley bottom. Alpine temperature -15.

Tuesday: Mostly cloudy. Light to moderate westerly wind. Freezing level 1300 m. Alpine temperature -7.

Wednesday: Sunny. Light to moderate southwest wind. Freezing level 1800 m. Alpine temperature -1.

Avalanche Summary

We are still awaiting reports of avalanche activity from the weekend's storm. A widespread natural cycle is likely to have occurred Sunday.

On Saturday, evidence of an old size 2 cornice failure was observed at Allen Creek. Otherwise, we have no reports of avalanche activity since Wednesday's storm when there were a few reports of natural and human triggered storm slab avalanches.

Snowpack Summary

The weekend's storm dropped another 20-50 cm of new snow over the region. This snow has likely been redistributed by strong wind, switching from southwest to northwest Sunday night. Crusty surfaces exist below treeline.

The new snow buries old stubborn slabs at upper elevations and a crust below treeline. Recent warm weather patterns are expected to have helped old persistent weak layers heal. The new snow load (and whether it triggers deeper slabs during the storm) may help shed some light on concerns over a facet layer 150 cm deep from the mid-February cold snap that resulted in few large cornice triggered avalanches in the first half of March.

Terrain and Travel

Be careful to keep storm day fever from luring you out into bigger terrain features.
Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Seek out sheltered terrain where new snow hasn't been wind-affected.
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.