Avalanche Forecast

Issued: Dec 18th, 2014 8:39AM

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

triley, Avalanche Canada

Northwest Inland.

Avalanche danger is increasing as the new storm moves in from the Southwest.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Very light snow overnight combined with moderate to strong Southeast winds and freezing levels at valley bottoms. Very light snow during the day on Friday with light to moderate Southwest winds. Light snow (5-10 cm) by Saturday morning combined with very strong Southerly winds. Snow and strong Southwest wind continuing during the day Saturday with another 5-10 cm expected to accumulate. Unsettled on Sunday with flurries or light snow, moderate Southwest winds and freezing levels at valley bottoms.

Avalanche Summary

There are no new avalanche reports from the region. The forecast new storm is expected to develop a new storm slab that may increase avalanche activity.

Snowpack Summary

The new storm is expected to develop a storm slab above the dusting of new snow which overlies weak surface hoar reported to exist up to at least treeline elevation. Below the new snow you'll likely find wind-scoured surfaces and old wind slabs in exposed terrain, and settled storm snow closer to treeline. Near the base of the snowpack, weaknesses such as the mid-November crust-facet layer are still of concern. I'd use extra caution around steep, unsupported high elevation terrain as avalanches at this interface could propagate over wide distances.

Problems

Storm Slabs

A new storm slab is expected to develop over the next few days as forecast snow and wind move into the region from the coast. Recent windslabs may be difficult to locate due to the new snow. Some loose dry snow may slide easily off of the old crust.

Use ridges or ribs to avoid wind loaded and cross loaded slopes.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

Persistent weaknesses buried in November remain a concern for professionals in the region. Watch for shallow snowpack trigger points on steep, unsupported slopes.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 19th, 2014 2:00PM