Avalanche Forecast

Archived

Apr 7th, 2017–Apr 8th, 2017

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Cariboos.

Watch for variable wind loading patterns as you gain elevation and maintain awareness of overhead hazards like cornices and large avalanche paths. A heavy trigger in the right location still risks triggering a very large and destructive avalanche.

Confidence

High -

Weather Forecast

Saturday: Mainly cloudy with isolated flurries and a trace of new snow. Light to moderate south winds. Freezing level to 1700 metres with alpine temperatures of -4.Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Light south winds. Freezing level to 1700 metres with alpine temperatures of -4.Monday: A mix of sun and cloud. Light southeast winds. Freezing level to 1900 metres with alpine temperatures of -3.

Avalanche Summary

No new avalanches were reported on Wednesday or Thursday.On Tuesday several natural cornice falls up to size 3.5 were reported, and several natural cornice falls were reported on Monday up to size 3.0.

Snowpack Summary

Recent light snowfall combined with moderate winds (mainly from the southwest) to form new wind slabs in the alpine and at treeline. These new wind slabs have been developing above a mix of old surfaces that include melt-freeze crusts below about 1900 metres and on solar aspects in the alpine. In some areas the new snow may hide some lingering wind slabs that are left from the last stormy period. Cornices have been a primary avalanche problem in the past week, with recent reports of cornices breaking off naturally with loading from wind, or due to warming from direct sun or daytime heating. The February weak layers are down about 120-150 cm and the deep mid-December facet layer and November rain crust both still linger near the bottom of the snowpack. These deep weak layers have recently produced large avalanches with heavy triggers like cornice falls, and they may be more likely to fail on southerly aspects during periods of strong solar radiation.

Problems

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.

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.

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.