Avalanche Forecast

Issued: Dec 28th, 2012 8:46AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Good

Weather Forecast

A light Northwesterly flow with weak embedded systems persist through Saturday. A “dirty ridge” of high pressure sets up and slowly pushes through by Sunday and into the outlook.Saturday: Snow amounts near 5 cm accompanied by light West ridgetop winds. Alpine temperatures near -7 and freezing levels at valley bottom.Sunday: Valley cloud expected sunny skies above and alpine temperatures near -4. High diurnal alpine temperature variations will host very cool temps in the morning with milder afternoon temperatures and freezing levels. By nightfall temperatures will fall and promote rapid cooling. Ridgetop winds will be light from the North. Freezing levels near 800 m.Monday: Alpine temperatures near -9 accompanied by light West ridgetop winds. Freezing levels at valley bottom.

Avalanche Summary

On December 24th Record Mt. had a natural size 2 slab avalanche. Reports indicate that the failure plane was the late November surface hoar layer buried down 115 cm. The avalanche occurred on a East aspect around 1900 m. Reports from the Rossland area suggest that the buried surface hoar is well preserved and the crystals are 10 mm in size. I suggest keeping this on your radar, it may be more suspectable to rider triggers in the Rossland Range.No new avalanche observations reported on Friday.

Snowpack Summary

The upper snowpack seems to be settling and bonding with no significant shears. Wind slabs have formed and may be easily triggered by a rider in specific places like: leeward slopes, and behind terrain features (spines, gullies).Through the region, people continue to monitor the late November buried surface hoar found down around 115-130 cm. Snowpack testing has shown compression and deep tap test results in the hard to very hard range with a variety of fracture characteristics, including no results, breaks and some with sudden results. This layer may be difficult to trigger, but you can expect a consequential avalanche to occur if this layer fails. Dig down, find and test weak layers that may exist in your neck of the woods. The mid-pack is generally well settled.

Problems

Wind Slabs

An icon showing Wind Slabs
Blowing winds from variable directions has redistributed recent storm snow on North-South aspects. Use extra caution on lee slopes, behind spines, and in wind exposed areas.
Dig down to find and test weak layers before committing to a line.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Dec 29th, 2012 2:00PM