Avalanche Forecast

Issued: Feb 14th, 2013 9:51AM

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

jlammers, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

Friday: Light to locally moderate snowfall continuing overnight / Strong to extreme southwest winds / Freezing level at 900mSaturday: Light snowfall / Moderate to strong northwest winds / Freezing level at 500mSunday: Light snowfall / Light southwest winds / Freezing level at 300m

Avalanche Summary

Natural activity to size 2.5 was reported in the north of the region. The cycle ran in steep terrain on all aspects at treeline and above, and occurred in response to recent storm loading.

Snowpack Summary

Up to 20cm of recently fallen snow has been distributed into deeper pockets of wind slab at treeline and in the alpine. In general, between 20-40cm of storm snow sits over a variety of old surfaces which include facets, crusts and isolated pockets of surface hoar (sheltered treeline and below treeline). There is very limited information about the nature of this interface, with the only reports 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 combined with strong to extreme winds will create fresh and reactive wind slabs. Due to the nature of the winds, watch for loading lower on the slope and in other unusual locations.

Be aware of the potential for wide propagations due to the presence of hard windslabs.>Be cautious as you transition into wind affected terrain.>

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.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Feb 15th, 2013 2:00PM