Avalanche Forecast

Issued: Jan 5th, 2013 8:51AM

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

triley, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

Overnight and Sunday: Light snow overnight should accumulate another 2-3 cms by morning, and another 2-3 cms during the day on Sunday. Moderate Westerly winds overnight should become light Southwesterly during the day.Monday: Strong Southwest winds are forecast to build as the next pulse of moisture moves in from the coast. Expect 5-10 cms with temperatures down to about -5.0 in the alpine.Tuesday: Another pulse of moisture should bring 5-10 cms more during the day combined with moderate Southwest winds.

Avalanche Summary

Explosive control in the Ningunsaw area resulted in large avalanches failing on the facet layer near the ground.

Snowpack Summary

Thin layers of dry cold snow are accumulating each day. In some areas this new snow has been transported into wind slabs. The recent cold and dry weather has caused the surface snow to facet and become weakly bonded. This weak bonding has resulted in dry loose snow sluffing out of steep terrain. Forecast new snow on top of this weak unconsolidated surface should continue to sluff easily. The base layers of the shallow snowpack have also facetted and become weaker. The relatively strong mid-pack has formed a bridge above the deep facets. The forecast storm over the next few days may create a storm slab above the weak surface layers, and/or over-load the mid-pack bridge. This type of incremental loading requires frequent assessments of the amount of loading above the weak layers, and whether that load will react as a consolidated slab.

Problems

Wind Slabs

New soft wind slabs are expected to develop due to the forecast new snow and wind. Old stiff wind slabs may continue to be reactive to the additional load of a skier or rider.

Avoid freshly wind loaded features.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

A deeply buried facet/crust weakness exists near the base of the snowpack. This layer could be triggered by large loads such as a cornice collapse or from a thin-spot trigger point.

Avoid shallow snowpack areas where triggering is more likely.>Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Jan 6th, 2013 2:00PM