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Avalanche Forecast

Archived

Apr 12th, 2014–Apr 13th, 2014

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

Regions

South Coast.

Avalanche danger can rise very quickly with warming and solar radiation. Be aware of changing conditions and overhead hazards. For more insight into spring messaging, check out our latest Blog Post.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Sunday

Weather Forecast

Sunday: Clear skies / Light and variable winds / Freezing level at about 2200mMonday: Clear with increased cloud late in the day / Light to moderate southwest winds / Freezing level at about 2200mTuesday: Overcast skies with very light precipitation / Light westerly winds / Freezing level at about 1500m

Avalanche Summary

On Saturday a few cornice collapses were reported in a neighboring region including a size 3 release. It is unclear if the cornice release triggered a slab on the slope below. I would expect continued loose wet activity and cornice fall with continued daytime warming on Sunday.In recent days a very large (unknown size) persistent slab avalanche was observed on the northwest face of Mt Matier. The trigger is unknown; however, it demonstrates the potential for destructive persistent slab avalanches. See Wayne Flann's Avalanche Blog for a photo.

Snowpack Summary

A melt-freeze crust exists on all aspects up to 2200 m, and dryer snow can be found on high northerly aspects. The recent warmer temperatures have helped to strengthen and settle the upper snowpack, especially on solar aspects. Isolated wind slabs may still exist, although I suspect they're gaining strength. Surface hoar growth has been noted on shady slopes at higher elevations, and large sagging cornices are becoming weak with daytime warming.The February crust/facet layer is now deeply buried 150 250 cm below the surface. This layer is mostly inactive at this time, but could re-awaken with extended warming, solar influence and large triggers like cornice fall.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.