Avalanche Forecast

Issued: Dec 28th, 2018 4:56PM

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

Avalanche Canada mbender, Avalanche Canada

Danger ratings are forecast for the south of the region where precipitation amounts and freezing levels are predicted to be higher Friday night through Saturday.

Summary

Confidence

Low - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

FRIDAY NIGHT: Snow, accumulation 10-15 cm in the south and 5-10cm in the north / Moderate to strong southwest wind / Alpine temperature -3C / Freezing level 900mSATURDAY: Snow, accumulation 15-25 cm in the south and 5-10 cm in the north  / Moderate to strong southwest wind / Alpine temperature -1 C / freezing level 1500-2000mSUNDAY: Mostly cloudy with sunny breaks / Light to moderate northwest wind / Alpine temperature -5 C / Freezing level 700 mMONDAY: Mix of sun and cloud / Light west wind / Alpine temperature -4 C

Avalanche Summary

Reports are limited, but no avalanches have been reported in past few days.

Snowpack Summary

15-30 cm of recent new snow covering what is reported to be a widespread weak layer of feathery surface hoar. Below this, about 30 cm of recent storm snow sits on a melt-freeze crust below around 1800 m. Reports are limited, but they suggest that the snow is bonding well to the crust. Expect the deepest deposits of storm snow to be in lee and cross-loaded terrain features.In the north portion of the region and possibly the far south, a weak layer of facets and surface hoar lies below all this storm snow, around 100 to 150 cm deep. The weak layer appears most prominent around treeline, up to 2000 m. There has not been reports of avalanche activity on this layer for the past week. Although this layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists.Near the base of the snowpack, a crust exists with weak and sugary facets beneath it. This could potentially still be of concern in high north-facing aspects where the snowpack rests on very smooth ground cover. A very large trigger, such as a cornice fall, would likely be needed to form an avalanche on this layer.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow combined with wind will promote the development of storm slabs. Thickest deposits will be found in the lee of terrain features. Rain at lower elevations may cause the surface snow to sluff in steep terrain.
Minimize overhead exposure during periods of heavy loading from new snow, wind.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A weak layer buried 100 to 150 cm has the potential to produce large avalanches. This layer is likely most problematic in the north of the region and possibly the far south, around treeline and lower alpine elevations.
Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Use conservative route selection and choose moderate-angled slopes with low consequence.Cornices are large and looming, and could trigger persistent slabs on slopes below.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Dec 29th, 2018 2:00PM