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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

South 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 3-5 cm of new snow. Light southwest winds. Alpine high temperatures to around -7.Thursday: Cloudy with flurries bringing 5-10 cm of new snow. Light south winds. Alpine high temperatures to about -5.Friday: A mix of sun and cloud. Light southwest winds. Freezing level rising to 1300 metres and alpine high temperatures to about -2.

Avalanche Summary

Preliminary reports from Tuesday describe 'electric' conditions in several areas in the South Columbias, where extensive storm slab reactivity was observed. It is as yet uncertain to what degree deeper persistent slab problems were active.Reports from Monday showed a continuation of recent heightened avalanche activity, with numerous storm slabs and persistent slabs releasing from Size 1 to 2.5 both naturally and with human triggers. Activity was observed on all aspects and elevations and slab depths have ranged from about 20-80 cm. This has been a consistent and increasing trend, with around 5-10 avalanches being reported each day for the past week on either the January 5 surface hoar or the much deeper December 15 surface hoar.Please share your observations through the Mountain Information Network.

Snowpack Summary

30-60 cm of new snow has accumulated on surface hoar in sheltered slopes and 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 also 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.