Avalanche Forecast

Issued: Dec 22nd, 2017 5:03PM

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

Avalanche Canada cgarritty, Avalanche Canada

Where there is uncertainty in the snowpack, conservative terrain is the answer. Check out today's Forecaster's blog for tips on managing the spatial variability associated with our current persistent slab problem. LINK

Summary

Confidence

Moderate -

Weather Forecast

Saturday: A mix of sun and cloud. Moderate northwest winds. Alpine temperatures of -15.Sunday: Mainly sunny. Light north winds. Alpine temperatures of -14.Monday: A mix of sun and cloud with cloud increasing in the afternoon. Light northwest winds. Alpine temperatures around -16.

Avalanche Summary

Touchy conditions were reported from the North Thompson area of the Cariboos on Wednesday, where steep banks in lower elevation cutblocks were observed releasing very easily with sled traffic. In the adjacent North Monashees, natural wind slab and storm slab releases were reported up to Size 2.5. Human-triggered slab avalanche potential can be expected to persist as our recent snow consolidates into a slab above the range of weak surfaces present at the December 15 interface. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Stormy weather over the past week has brought 20-40cm of new snow to the region. The new snow lies over a wide variety of old surfaces, including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. The bond at this old snow interface becomes critical as the overlying snow gradually consolidates 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 and sheltered northerly aspects in the alpine. Additionally, any steep solar aspects where surface hoar may be sitting on sun crust should be considered areas where this weak layer may be more likely to trigger. A crust which was formed by rain in late November is a 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. Snowpack depth decreases rapidly below tree line. Look out for early season hazards such as rocks, stumps, and open creeks.

Problems

Wind Slabs

An icon showing Wind Slabs
Shifting winds since the storm have been redistributing new snow into wind slabs on a variety of aspects. The most recent of these are the result of Friday's north to northeast winds. Keep this reverse loading pattern in mind as you gain elevation.
Be aware of areas that have been reverse loaded by windsUse ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
Reactivity at the buried December 15 interface will likely be greater where the new snow has settled into a cohesive slab above buried surface hoar. Use extra caution in wind affected areas and around steeper, sheltered slopes at treeline and below.
Buried surface hoar may be preserved on open slopes and convex rolls at and below tree lineWatch for whumpfing, shooting cracks, or signs of recent natural avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 23rd, 2017 2:00PM