Avalanche Forecast

Issued: Mar 18th, 2012 4:00PM

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

pmarshall, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Monday: A mix of sun and cloud with a slight chance of flurries in some areas. The freezing level should be at valley bottom overnight, rising to 500-600m during the day. Winds are light, rising to moderate from the SE in the afternoon. Tuesday and Wednesday: Light to moderate snow - 5-10cm each day. The freezing level is around 500m and winds are moderate to strong from the S-SW.

Avalanche Summary

Several natural cornice failures were observed, but generally with minimal slab initiation. There were also reports of loose snow avalanches up to Size 2 in steep terrain.

Snowpack Summary

Moderate amounts of low density snow sit over a variety of old surfaces that include widely distributed hard wind slabs, or melt freeze crusts that exist on most aspects below 1000m and on solar aspects as high as 1600m. In exposed areas the newer snow has been shifted into deeper pockets of soft wind slab. The mid February persistent weak layer interface, comprised of spotty surface hoar, facets and crusts, is buried 80-120 cm below the surface. No recent activity has been reported on this interface. However, recent snowpack tests have been giving hard but sudden "pop" results and indicate it is has the potential to react given the right trigger in the right place. For route selection, it should still be on your radar and is more likely to be triggered on steeper, unsupported terrain. Cornices in the area are reported to be very large and primed for natural collapse or triggering by a person.

Problems

Wind Slabs

Recently formed wind slabs may exist on lee slopes adding to a strengthening hard wind slab problem that developed last week.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Cornices

Large cornices exist in alpine terrain. A failure could be destructive by itself, and could also trigger an avalanche on the slope below.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Persistent Slabs

The likelihood of triggering persistent layers buried in early February is greatest on steep, unsupported terrain . Although no recent avalanches have been reported, the chances of triggering may increase with solar radiation forecast for the weekend

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 19th, 2012 9:00AM