Avalanche Forecast

Issued: Feb 13th, 2013 9:50AM

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

jlammers, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Thursday: Light to locally moderate snowfall / Strong to extreme west winds / Freezing level at 700mFriday: Moderate snowfall / Extreme southwest winds / Freezing level at 900mSaturday: Light snowfall / Moderate southwest winds / Freezing level at 500m

Avalanche Summary

No recent reports, but we have had very few observations.

Snowpack Summary

Recent light to locally moderate snowfall has likely set up new wind slabs in exposed lee areas. Previous buried surfaces lie buried approximately 20-40cm below the surface. These 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

Generally light snowfall and extreme winds are expected to add to the current wind slab problem. Watch for triggering below rolls and in the lee of ridge crests.

Be cautious as you transition into wind affected terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

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.

Choose well supported terrain without convexities.>Make observations and assess conditions continually as you travel.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Feb 14th, 2013 2:00PM