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

Apr 11th, 2014–Apr 12th, 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, human triggered possible.
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. Terrain choices and timing can be critical.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Overview: A ridge of high pressure will dominate the coast by Saturday morning bringing mainly sunny skies and rising freezing levels for the forecast period.Saturday: Mostly clear skies / Moderate northerly winds / Freezing level at about 1600mSunday: Clear skies / Light northerly winds / Freezing level at about 1700mMonday: Mostly clear skies with increased cloud late in the day / Light southwest winds / Freezing level rising to about 2600m

Avalanche Summary

Cornices have started to fail up to size 2.5 with warmer temperatures and sunny skies. Of the cornice fall observed, none triggered deeper slabs on the slopes below. Numerous loose wet avalanches occurred up to size 2 on steeper solar aspects, and are expected to continue with forecast warming. Also, 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

Up to 20 cm of recent snow sits above a solid melt freeze crust. The new snow seems to be bonding with help from the warmer temperatures; however, isolated wind slabs may still exist. Surface snow is seeing daily a melt-freeze cycle on all aspects below 2000m, and to mountain top on southerly aspects.Surface hoar growth has been noted on shady slopes at higher elevations, and large sagging cornices are becoming weak with daytime warming.A couple persistent weak layers exist deeper in the snowpack. The early March crust layer is down 60 - 100cm and the February crust/facet layer is now deeply buried down 150 250 cm. These layers are 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.