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 Inland.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Synopsis: A series of frontal systems are expected to bring generally light precipitation to the region Monday and Tuesday, with a drying trend on Wednesday.Monday: Flurries. Freezing level around 700m. Strong SW winds gusting to 60 km/h at ridgetop.Tuesday: Around 5cm new snow. Freezing level around 900m. Strong southwesterly winds gusting to 70 km/h at ridgetop in the morning, diminishing in the afternoon.Wednesday: Dry, with a mix of sun and cloud. Freezing level at valley bottom. Light NW winds.

Avalanche Summary

Recent loose snow avalanches were reported during the recent warm weather.

Snowpack Summary

Around 20-40cm recent new snow sits on a variety of old surfaces, which vary from facets to crusts and isolated pockets of surface hoar (sheltered treeline and below treeline). There is very limited information about the nature of the interface, with the only results suggesting reactivity in sheltered, shady treeline and below treeline slopes (preserved surface hoar). I would stress the importance of digging down to find and test weak layers.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow compared to averages; triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

Problems

Wind Slabs

New snow and shifting winds have built wind slabs that are likely found behind terrain breaks such as ridges and ribs. Watch for katabatic winds descending from glaciers.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Persistent Slabs

Buried beneath the new snow sits a surface hoar/crust/facet weakness. This may be sensitive to rider triggers in steeper sheltered terrain or over convex rolls, especially at treeline and below treeline elevations.

Dig down to find and test weak layers before committing to a line.>Assess start zones carefully and use safe travel techniques.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

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