Avalanche Forecast

Issued: Dec 23rd, 2017 4:42PM

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

cgarritty, Avalanche Canada

Cariboos.

Slab formation remains the critical factor for avalanche danger under current conditions. The best and safest riding will be in soft, unconsolidated snow.

Summary

Confidence

Moderate -

Weather Forecast

Sunday: Mainly sunny. Light north winds. Alpine temperatures around -13.Monday: Mainly sunny. Light north winds. Alpine temperatures around -16.Tuesday: A mix of sun and cloud. Light southwest winds. Alpine temperatures around -16

Avalanche Summary

No new avalanches have been reported in the region. Touchy conditions were reported from the North Thompson area of the Cariboos on Thursday, where steep banks in lower elevation cutblocks were observed releasing 'remotely' (from a distance) over the December 15 surface hoar layer. In the adjacent North Monashees, natural wind slab and storm slab releases were reported up to Size 2.5 on Wednesday.In addition to wind slab problems at higher elevations, persistent slab avalanche danger can be expected to persist in areas where our recent snow has consolidated into a slab above the December 15 interface. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Last week's stormy weather brought 20-40cm of new snow to the region. Shifting winds (most recently from the north) have redistributed the new snow into wind slabs on a variety of aspects at higher elevations while cold temperatures have inhibited slab formation in wind-sheltered areas. The new snow lies over a variety of old surfaces, including large surface hoar (weak, feather-like crystals), crusts formed by sun or wind, and sugary facets. The bond at this old snow interface is of critical importance in areas where the overlying snow has consolidated into a slab. The most concerning areas areas will be those that have seen previous surface hoar development, such as sheltered areas at and below tree line.A crust which was formed by rain in late November is another major feature in the snowpack and is down approximately 70-100cm at tree line elevations. Snowpack tests suggest the snow above is currently bonding well to it.

Problems

Wind Slabs

Shifting winds since the storm have been redistributing new snow into wind slabs on a variety of aspects. The freshest slabs are the result of recent northerly winds. Keep this reverse loading pattern in mind as you gain elevation.

Use ridges or ribs to avoid pockets of wind loaded snow.Be aware of areas that have been reverse loaded by recent winds

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

The December 15 interface will likely be most reactive where the new snow has settled into a slab over buried surface hoar. Use extra caution around steeper, sheltered slopes at treeline and below - especially if you see signs of slab formation.

Watch for signs of slab formation at lower elevations, such as whumphing or shooting cracks.Buried surface hoar is more likely to be preserved in sheltered openings at and below tree line.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 24th, 2017 2:00PM