Avalanche Forecast

Archived

Dec 21st, 2013–Dec 22nd, 2013

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Northwest Inland.

Forecasters are working without field data at this time. If you are traveling in the backcountry we'd love to hear about what you're seeing out there! [email protected]

Confidence

Poor - Due to the number of field observations

Weather Forecast

Synopsis: The pattern switches to a more southwesterly flow over the next 24 hours. The Smithers area should see a bit of rain/snow while other snow holes in the region could see up to 20 cm at upper elevations.Sunday: Freezing Level: 1800m Precip: Snow & Rain 5/10mm 10 /20cm Wind: Mod gusting Extreme, SWMonday: Freezing Level: 900m Precip: Nil Wind: Strong, W Tuesday: Freezing Level: Valley Bottom Precip: Nil Wind: Lht W gusting Strong.

Avalanche Summary

A few small wind slabs just below ridge crest were reported on Dec. 15. No other avalanches have been reported. This likely speaks more to the lack of observations than actual conditions.

Snowpack Summary

We've received one observation from this region in the last week. As a result, you need to take this discussion with a grain of salt, so to speak.There is significant variation in snow depths across the region. In the Smithers area the ski hill is reporting an 89 cm base. Treeline depths vary between 100 - 180 cm.The region has picked up 5 - 20 cm of cold new snow over the last three days. Last weekend's storm finished very warm, as a result a crust can be found near the snow surface below 1100m. The best guess is that the last storm produced around 10 - 50 cm of snow. This snow now overlies the layer of facets/surface hoar that sit above old wind slabs and melt-freeze crusts which were formed during the December cold/dry spell. We don't have great wind stations in the region, but the coast saw a lot of strong wind during the last storm & I suspect this region was similarly hammered by wind. The mid and lower snowpack is still structurally weak due to facets, potentially even depth hoar and an early season crust near the ground.

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.