Avalanche Forecast

Issued: Dec 29th, 2018 4:21PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs.

Avalanche Canada mbender, Avalanche Canada

A more stable weather pattern is forecast for the next few days, however newly formed storm and wind slabs will need several days to settle and bond.

Summary

Confidence

Moderate -

Weather Forecast

SATURDAY NIGHT: Cloudy with isolated flurries and clear periods / Moderate northwest wind / Alpine temperature -6 CSUNDAY: Mostly cloudy with sunny breaks / Moderate northwest wind / Alpine temperature -7 C MONDAY: Mix of sun and cloud / Light north wind / Alpine temperature -5 CTUESDAY: Mainly Cloudy / Light west wind / Alpine Temperature -3 / Freezing level 700 m

Avalanche Summary

Recent avalanche activity has been reported as several explosives controlled size 2 storm and wind slabs in the alpine and tree line. Some of these avalanches were running on a layer of surface hoar buried around December 23. There was also a report of a size 3 wind slab avalanche that released sympathetically to an avalanche that was set of by an explosive about 30m away.

Snowpack Summary

40-50 cm of recent new snow sits on a weak layer of feathery surface hoar. Snow amounts will be deepest and touchiest in the lees of terrain features immediately adjacent to ridges.Below 1800 m, around 50 cm of storm snow may not be bonding well to an underlying crust (see here).A weak layer of sugary facets and surface hoar lies around 150 to 200 cm deep in the snowpack. There hasn't been reports of avalanches on this layer for over a week. That being said, this layer may still exist in isolated areas around treeline in some portions of the region.At the base of the snowpack, weak and sugary facets are found below an early-season melt-freeze crust. This weak layer has been the culprit for sporadic, very large avalanches in alpine terrain in the past few weeks. The avalanches have occurred in areas where the ground roughness is very smooth, for example glaciers, firn, and shale/rock slab slopes. An avalanche could be triggered in this layer with a very large trigger, such as a cornice fall.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm snow accumulating over a newly formed weak layer will require time to bond. Strong to extreme southerly winds overnight Friday through Saturday have created deep deposits in the alpine and well into tree line.
Observe for the bond of recent storm snow to underlying surfaces before entering avalanche terrain.Use caution in lee areas; thicker deposits are expected due to recent wind loading.Cornices are large and looming near ridges. Give them a wide berth.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Dec 30th, 2018 2:00PM