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Avalanche Forecast

Archived

Jan 9th, 2018–Jan 10th, 2018

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

Regions

North Columbia.

"Touchy", "electric", "spicy"... A few of the words that have been used to describe recent conditions. Avalanche activity has been extensive and is set to persist over the coming days. Choose low angle, low consequence terrain.

Confidence

Moderate -

Weather Forecast

Wednesday: Mainly cloudy with scattered flurries and a trace to 5 cm of new snow. Light southwest winds. Alpine high temperatures to -11.Thursday: Mainly cloudy with scattered flurries and approximately 5 cm of new snow. Light variable winds. Alpine high temperatures to -9.Friday: A mix of sun and cloud. Light to moderate west winds. Alpine high temperatures to -9.

Avalanche Summary

Reports from Monday showed a continuation of Sunday's activity, with numerous persistent slabs and storm slabs releasing naturally and with remote (from a distance) triggers. Sizes ranged from small to large (Size 1-2) with slab depths of 10-60 cm. Activity was observed on all aspects and elevation ranges. On Sunday, numerous avalanches were triggered naturally and by skiers on the December 15 surface hoar layer at and below treeline on all aspects. The avalanches were small to large, being reported between size 1 and 2.5 with depths of about 40 to 50 cm. This has been a consistent and increasing trend, with around 5-10 avalanches being reported on this layer each day for the past week.Please share your recent observations through the Mountain Information Network (MIN).

Snowpack Summary

30-60 cm of new snow has accumulated on surface hoar in sheltered slopes and over a sun crust on steep solar aspects. Numerous storm slab avalanches resulted as the new snow consolidated into a slab before bonding to the underlying surface. Strong southwest winds have accelerated slab formation at higher elevations. The additional snow has increased the reactivity of a number of buried weak layers. 50-100 cm of snow now overlies a layer of weak and feathery surface hoar, found primarily at and below treeline. Dubbed the December 15 surface hoar, this layer has been the failure plane in many recent destructive slab avalanches. See the Avalanche Summary for recent activity. Deeper in the snowpack (90 to 150 cm), a crust that formed back in November is producing variable test results (sudden to no result). This layer is considered dormant but could be triggered in thin spots around variable-depth snowpack areas in the alpine.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.