Avalanche Forecast

Issued: Mar 1st, 2013 9:16AM

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

jfloyer, Avalanche Canada

Northwest Inland.

Considerable danger remains for alpine areas in high snow areas.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Synopsis: A benign weather pattern will bring initially flurries and then clearer skies for the region through the forecast period.Saturday: Flurries. Southwesterly ridgetop winds to 30 km/h. Freezing level around 600 m.Sunday: Clearing through the day. Light northwesterly winds. Freezing level around 600 m.Monday: Clear with some good sunshine. Light southeasterly winds. Freezing level around 600 m.

Avalanche Summary

Small (size 1) soft slab avalanches could be triggered in response to ski-cutting at treeline on north aspect slopes through the whole week. On Thursday, a size 1.5 avalanche was human-triggered below treeline on a north aspect running on a melt-freeze crust.

Snowpack Summary

Recent storm snow amounts are 30-40 cm in the west of the region and more like 10 cm in the east. Strong southwest winds have formed touchy wind slabs in exposed terrain in the lee of ridges, gully side walls, and behind terrain features. There are a variety of old interfaces now down 60 - 100cm which include facets, crusts and isolated pockets of surface hoar. Recent observations indicate that these weaknesses have bonded fairly well now, but I still suggest digging and testing the snowpack to confirm.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 in northern and eastern parts of the region. 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

Strong winds throughout the region have set up touchy wind slabs in the lee of ridges and terrain features. Watch also for growing cornices.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Storm Slabs

Storm slabs remain in the west and the south of the region where there were deeper recent snow amounts. In particular, watch areas where snow overlies a crust at treeline and below.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Mar 2nd, 2013 2:00PM