Avalanche Forecast

Archived

Dec 21st, 2014–Dec 22nd, 2014

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 possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Inland.

If you have been out over the weekend, it would be great to find out what you saw in your area. Please email observations to [email protected]

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

Light snowfall overnight combined with moderate Southwest winds and freezing levels at valley bottoms. Clearing and cooling on Monday as a ridge of High pressure builds over the province. Strong Southwest winds and snow beginning during the day on Tuesday and continuing into Wednesday. Freezing levels remaining at valley bottoms.

Avalanche Summary

There are no new avalanche reports from the region.

Snowpack Summary

The new storm slab is between 20-40 cm deep. Very strong winds have transported snow in the alpine and at treeline into pockets of windslab that may not be well bonded to the old surfaces. Below the new snow you'll likely find wind-scoured surfaces and old wind slabs in exposed terrain, and settled storm snow closer to treeline. Near the base of the snowpack, weaknesses such as the mid-November crust-facet layer are still of concern. I'd use extra caution around steep, unsupported high elevation terrain as avalanches at this interface could propagate over wide distances.

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.