Avalanche Forecast

Issued: Feb 9th, 2013 9:36AM

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

jfloyer, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Good

Weather Forecast

Synopsis: Several low intensity pulses of precipitation will bring light to moderate precipitation amounts through the period, focussed mostly along extreme coastal areas.Sunday: Light to moderate snowfall starting in the afternoon (5-10 cm). Southwesterly winds around 50 km/h at ridgetop. Freezing level around 900m.Monday and Tuesday: 5-10 cm new snow each day. Freezing level around 500 m. Moderate to strong southwesterly winds.

Avalanche Summary

Avalanche activity has tapered off, with only one size 2 skier-triggered avalanche on a steep north slope reported from Friday.

Snowpack Summary

Recent weather has been relatively benign, with precipitation pulses giving incremental loading (5-10cm at a time). Relatively light winds have accompanied these snowfall pulses with some stronger outflow winds closer to the coast. At elevations below 1300 m you might find a crust on the surface from warm temperatures and/or from previous drizzly rain.In the upper snowpack, various melt-freeze crusts remain a concern. Depending on your location, you may encounter crusts as shallow as 40cm and as deep as 110cm. Recent compression tests show both resistent and sudden planar results and an extended column test showed a continued propensity for propagation if the layer was triggered. It is certainly worth keeping these layers on your radar in regards to distribution and reactivity in the areas that you are riding. The mid and lower snowpack is generally well settled..

Problems

Wind Slabs

Windslabs have formed in response to westerly and southwesterly winds in exposed lee areas. Katabatic outflow winds from glaciers and icefields have also been reported. Watch for wind loaded slopes in these areas.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

Various crust layers in the upper snowpack (location specific) still shows sudden results and a propensity for propagation in snowpack tests. Local investigation to test distribution and reactivity is a good idea before committing to steep slopes.

Dig down to find and test weak layers before committing to a steep line, particularly on south facing slopes.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 10th, 2013 2:00PM