Avalanche Forecast

Archived

Mar 25th, 2014–Mar 26th, 2014

Alpine

Natural avalanches possible, human triggered probable.

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, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

South Coast.

Confidence

Fair - Forecast snowfall amounts are uncertain on Wednesday

Weather Forecast

Overnight and Wednesday: Expect 5-10 mm of precipitation overnight that should be 10-15 cm of snow at alpine elevations. Strong South-Southwest winds are forecast that should drop to light in the morning when the snow fall ends. Freezing level should drop down to about 600 metres overnight and rise to about 1300 metres during the day. There is a chance of broken skies and sunny periods in the afternoon.Thursday: Overcast with light Easterly winds, some light flurries, and freezing levels rising to 1400 metres.Friday: Snow starting in the morning as Southwest winds build to moderate values. Freezing levels rising to 1600 metres.

Avalanche Summary

No new reports of avalanches.

Snowpack Summary

10-15 cm of new snow is reported to be settling and bonding to the recent storm snow. The persistent weak layers from early March and early February continue to be a concern. The March weak layer of wind-scoured crusts, melt-freeze crusts, and/or surface hoar is reported to be down 70-80 cm. The February crust/facet/surface hoar layer is now deeply buried down 150-250 cm and may still be triggered by heavy loads like cornice falls or storm slab avalanches in motion. Long fracture propagations resulting in very large avalanches are possible with this layer. Avalanches releasing on these layers may step down to the ground during periods of strong solar radiation or warm spring rain.

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.

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.