Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Mar 5th, 2018–Mar 6th, 2018

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Sea To Sky.

A buried weak layer is capable of producing large human-triggered avalanches. Be aware of signs of instability such as whumpfing and stick to small supported terrain features.

Confidence

Moderate -

Weather Forecast

TUESDAY: Clouds clearing in the morning and then sunny in the afternoon, light west wind, freezing level rising to around 1000 m.WEDNESDAY: Sunny, light wind, freezing level rising to around 1300 m.THURSDAY: Flurries increasing throughout the day with 5-10 cm of snow by the afternoon, moderate southwest wind, freezing level rising to around 1200 m.

Avalanche Summary

On Sunday, a MCR report from the Blackcomb backcountry has a picture of a large remotely triggered avalanche (see here). This size 3 avalanche occurred on a west aspect around 1900 m and presumably failed on the buried surface hoar layer. A few similar, but slightly smaller, avalanches were reported in nearby terrain at similar elevations and on a range of aspects. This persistent weak layer will likely remain reactive to human triggers throughout the week.On Saturday, a few natural size 1-2 slabs were reported on north aspects and numerous wet loose avalanches were reported on steep south-facing terrain. Several small snowmobile triggered avalanches (size 1) were reported at treeline elevations in the Brandywine area.On Friday, a few human triggered avalanches up to size 2.5 were reported. A size 1.5 and a size 2.5 were triggered on southwest facing slopes between 1900 and 2000 m. These likely failed on the buried persistent weak layers.

Snowpack Summary

A thin sun crust has formed on solar aspects and the surface is wind affected in most exposed terrain. Last week's storms buried a weak layer composed of soft facets, surface hoar, and/or crust roughly 50-100 cm below the surface. This layer has produced whumpfing, sudden results in snowpack tests, and some remotely triggered avalanches. Lots of the activity has been on buried surface hoar on north aspects at upper treeline elevations. The snowpack is well settled and strong beneath this interface. Variable winds in the past month have produced cornices on many ridgelines. They will become touchier as they grow in size, as temperatures rise, and when they are subject to the strong late-winter sun on clear days.

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.

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.