Avalanche Forecast

Issued: Jan 3rd, 2018 4:57PM

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

Avalanche Canada mbender, Avalanche Canada

Expect to continue to see persistent slab avalanche activity as the snow sitting above the persistent weak layer further settles and consolidates with forecast warmer temperatures.

Summary

Confidence

Low - Freezing levels are uncertain

Weather Forecast

THURSDAY: Mainly cloudy / Alpine temperature -5 with possible temperature inversion above 2500m / Wind light westFRIDAY: Mainly cloudy with isolated flurries / Alpine temperature -1 / Wind light to moderate southwestSATURDAY: Mainly cloudy with isolated flurries / Alpine temperature -1 / Wind light to moderate southwest

Avalanche Summary

There have been several natural avalanches (and the greatest concern) between 1600m and 1800m on steep or open glades on all aspects... this is where the mid December layer has been most active. On Tuesday we had reports of several small loose avalanches triggered by the sun and warmer temperatures in the alpine. On Sunday we had reports of small features being reactive to sled cutting. See here for the MIN report - great information from a low-consequence slope. Additionally, an explosives-triggered Size 2.5 persistent slab avalanche was reported on a south east aspect at 1700m near Fernie, running on the mid-December surface hoar layer (down 65cm in that location).

Snowpack Summary

The mid-December layer (with variable distribution, but commonly found between 1600m and 1800m) is now buried 40-70 cm below the surface. This layer includes crusts on south and west facing slopes and feathery surface hoar in sheltered areas at and below treeline, and has been producing moderate, sudden results in recent snowpack tests.At higher elevations, winds (at times strong from the south west) have modified the snow pack, creating an "upside-down" slab layer with stiffer snow on top of softer snow.The lower snowpack is generally well settled with a thick prominent crust that was buried near the end of November.

Problems

Persistent Slabs

An icon showing Persistent Slabs
A weak layer composed of surface hoar and/or crusts is buried 40-70 cm below the surface. This layer continues to reactive.
Watch for whumpfing, hollow sounds, and shooting cracks.Choose well supported terrain without convexities.Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

An icon showing Wind Slabs
Moderate winds have created fresh wind slabs in the alpine.
Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 4th, 2018 2:00PM

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