Avalanche Forecast

Issued: Jan 20th, 2014 9:14AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm 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.Monday: Precip: 5/10mm 5/15cmTuesday: Freezing Level: Inversion, Above Freezing Air from 1500 2000m; Precip: Nil; Wind: Mod, SW.Wednesday: Freezing Level: 1500m; Precip: Trace Wind: Mod, SWThursday: Freezing Level: 3000m. Precip: Trace; Wind: Mod, SW

Avalanche Summary

A few small wind slabs were reported from N/NE facing terrain Sunday. A large avalanche was observed on a SW face in the north of the region. The deep persistent slab failed naturally resulting in a size 3 avalanche.

Snowpack Summary

Previously strong winds have left widespread wind loading/wind damaged snow in their wake. Most of these wind slabs are probably growing old and tired but may still pose a problem in bigger terrain. Warming 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

Storm Slabs

New snow and wind Monday will likely form fresh sensitive wind slabs, but they should be quite manageable. Soft new wind slabs will cover stubborn old wind slabs that may still be sensitive to human triggering on convexities and thick to thin spots.

Avoid freshly wind loaded features.>Travel on ridgetops to avoid wind slabs on slopes below.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

Valid until: Jan 21st, 2014 2:00PM