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Avalanche Forecast

Archived

Mar 13th, 2014–Mar 14th, 2014

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 possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.

Regions

South Columbia.

The current snowpack presents a serious challenge. Check out our latest blog for a look into the recent avalanche cycle and our best guess into what the future holds.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Saturday

Weather Forecast

Synopsis: A quick hitting system passes over the region Friday before a significant and warm rain/snow event arrives Saturday night and then settles in Sunday. Precip amounts and freezing Levels vary significantly from one model to the next, thus overall confidence in this Wx is Fair. Friday: Freezing Level: 1300m - 1800m; Precip: 3/11mm - 4/13cm; Treeline Wind: Light, SW | Mod SW at ridgetop.Saturday: Freezing Level: 1200m; Precip: Nil; Wind: Lht, SWSaturday Night: Freezing Level: 1600m - 1800m; Precip: 8/15mm - 8/16cm; Treeline Wind: Mod, W | Extreme SW at ridgetop.Sunday: Freezing Level: 1600m - 1800m; Precip: 2/13mm - 2/16cm; Treeline Wind: Strong, SW | Extreme SW at ridgetop.

Avalanche Summary

A couple of natural avalanches to size 2 were observed Wednesday while explosive control work produced avalanches to size 3.5 on N through E facing slopes. In one case, explosive control work resulted in a size 3 avalanche which sympatheticly triggered a second size 3 on the other side of the ridge.There was an absence of human triggered activity Wednesday, but it's worth noting a few stand out events from the last few days:On Monday a splitboarder triggered a size 2.5 storm slab on a west aspect in the Revelstoke area. No injuries were reported. In the southeast corner of the region a vehicle remotely triggered a size 2.5 slab avalanche on the February 10th interface. Last Saturday's avalanche fatality occurred in the Keefer Lake area northeast of Cherryville. The avalanche, which occurred in a cut block at about 1700m, involved 3 sledders who were in a party of 6. 2 of the men were able to inflate their airbags and were partially buried. The deceased was reportedly not able to inflate his airbag, and was buried approximately 5m below the surface.

Snowpack Summary

50 - 120 cm of recent storm snow rests on small grained surface hoar in sheltered areas and a sun crust on solar aspects. In upper elevation wind exposed terrain the new snow has been pushed into deep wind slabs by moderate SW winds.The freezing levels remain high (aprox. 1800m) in this spring like pattern. Below treeline the snowpack is seeing a daily melt freeze cycle that has left many features wet and sloppy by the afternoon. This has created an isolated wet slab problem that has been responsible for serious incidents recently. At ridgetop cornices are large and unsupported.The February 10th surface hoar/facet/crust combo is 80 - 250cm below the snow surface and widespread throughout the region. Surface avalanches in motion, cornice fall and/or solar radiation all have the potential to initiate an avalanche on this deeply buried weak layer. Interestingly, we continue to hear about remote triggering at this interface. For the most part, the mid and lower snowpack are strong and well consolidated.

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.