Avalanche Forecast

Issued: Jan 21st, 2014 9:09AM

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

ghelgeson, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair

Weather Forecast

Synopsis: A frontal system takes a small bite out of the ridge Tuesday resulting in very limited precip for the northwest corner of the province. The ridge comes back with a vengeance Wednesday and should persist through the weekend.Wednesday: Freezing Level: Valley Bottom; Precip: Trace Wind: Mod, SWThursday: Freezing Level: 2500m; Precip: Nil; Wind: Lht, SW Strong W at ridgetop.Friday: Freezing Level: 3000m; Precip: Nil; Wind: Lht, Variable, Strong W at ridgetop.

Avalanche Summary

No new observations from Monday. An anomalous large avalanche was observed on a SW face in the north of the region on Sunday. The deep persistent slab failed naturally resulting in a size 3 avalanche.

Snowpack Summary

The region picked up 10 - 20 cm of new snow on Monday which now hides most of the destruction caused by previously strong winds that left widespread wind loading/wind damaged snow in their wake. Previously warm temps along with a bit of rain at lower elevations has formed a variety of crusts at and below treeline. The early January surface hoar is most active in the north of the region between 900m and 1400m. It was a player during the last cycle even in low angled terrain. Look for it 70 -100 cm below the surface. Professionals continue to keep an eye on the basal facets which can be found down around two meters below the snow surface.

Problems

Wind Slabs

Winds have been blowing with enough gusto to redistribute Monday's 10 - 20 cm of new snow into fresh sensitive wind slabs. There's a chance that wind slab avalanches could step down and trigger some of the deeper weaknesses.

Avoid freshly wind loaded features.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>The recently formed wind slabs will need a couple days to settle out.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

Two weaknesses have the potential to surprise folks: Surface Hoar one meter below the surface and very weak basal facets near the ground. Vigilant slope by slope evaluation and/or a modest terrain approach are appropriate at this time.

Avoid convexities or areas with a thin, rocky or variable snowpack.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

Valid until: Jan 22nd, 2014 2:00PM