Avalanche Forecast

Issued: Feb 4th, 2013 9:28AM

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.

mpeter, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Tuesday: Expect clouds to develop, with a chance of light flurries. Alpine temperatures should reach -7 with light to moderate south-southwesterly winds.Wednesday & Thursday: Clouds persists with flurries tapering through the forecast period. Winds continue to be light from the southwest with alpine temperatures reaching -7 each the afternoon.

Avalanche Summary

Isolated windslabs up to size 2.0 have been controlled at ridgecrest and loose wet sluffing has been observed below 1200m.

Snowpack Summary

Wind slabs have built on lee slopes and behind terrain features likes ribs and ridges. In some locations up to 50 cm of new snow has buried a variety of old surfaces including old wind slabs, scoured thin slopes, crusts and surface hoar. This interface has shown isolated reactivity to rider triggering, especially around treeline and below treeline elevations. Recent warm temperatures have promoted some settlement and consolidated the recent snow into slab-like characteristics. With little observations from the field it's hard to get a good handle on how widespread this layer is, so I would stress the importance of digging down to find and test weak layers. A cautious and curious approach is critical.The average snowpack depth at treeline is near 100 cm but remains quite inconsistent across the region. A strong mid-pack currently overlies a weak base layer of facets/depth hoar. Triggering of this 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 strong shifting winds have built wind slabs that are likely found behind terrain breaks such as ridges and ribs.

Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

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.>Be cautious with convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Feb 5th, 2013 2:00PM