Avalanche Forecast

Issued: Feb 10th, 2013 3:00PM

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: A series of frontal systems are expected to bring moderate precipition amounts to the region Monday and Tuesday, with a drying trend on Wednesday.Monday: Around 5cm new snow, maybe a little more for areas right next to the coast. Freezing level around 700m. Strong SW winds gusting to 70 km/h at ridgetop.Tuesday: 10-20cm new snow. Freezing level around 700m. Strong southwesterly winds gusting to 70 km/h at ridgetop.Wednesday: Dry, with a mix of sun and cloud. Freezing level at valley bottom. Light NW winds.

Avalanche Summary

Small avalanches (size 1) were human-triggered in wind slab deposits on Saturday.

Snowpack Summary

Recent weather has been relatively benign, with generally light snowfall adding 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 close to the surface from recent warm temperatures and/or 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 indicated a 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 layers are 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 show 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 line.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

2 - 6

Valid until: Feb 11th, 2013 2:00PM