Avalanche Forecast

Issued: Mar 10th, 2014 9:26AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Storm Slabs and Persistent Slabs.

rbuhler, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Good

Weather Forecast

A Pacific frontal system will arrive on the North Coast Tuesday morning and storm conditions should persist through Wednesday. Thursday is expected to be relatively dry.Tuesday: Snow or rain 15-20mm, freezing level 700m overnight, 1200-1400m afternoon, ridgetop winds 60-80 km/h SWTues. Night/Wednesday: Snow or rain 20-30mm, freezing level 1200-1400m overnight, falling to around 1000m in the afternoon, ridgetop winds 60-80 km/h SW, easing in the afternoonThursday: A mix of sun and cloud, dry conditions, freezing level 500m overnight, 800m afternoon, ridgetop winds light S-SW

Avalanche Summary

On Saturday and Sunday, we received reports of many size 2-3 slab avalanches from higher elevations on a variety of aspects. Most of these seemed to release within the recent storm snow or on the previous snow surface buried on March 7. Also reported were numerous natural loose wet avalanches up to size 2 below treeline from warming temperatures and rain.

Snowpack Summary

Around 50-80cm of recent storm snow now sits on previous snow surface which may consist of the following: (1) hard wind slabs or wind-scoured slopes in exposed terrain, (2) a thick layer of faceted snow on sheltered, shady slopes, (3) isolated surface hoar on sheltered, shady slopes, and (4) sun crust on steep solar aspects. Expect moist or wet snow below 1000m, possibly with one or two new crusts near the surface. The mid February weak layer of surface hoar or a crust/facet combo is buried 90-150cm deep. This layer continues to react in snowpack tests, primarily on sheltered north aspects at or below treeline. Basal facets and/or depth hoar remain a concern in shallow snowpack areas in the northern part of the region.

Problems

Storm Slabs

More new storm snow will continue to load slopes. Some areas have received up to 80cm of snowfall since Friday. Avalanches may release within the storm snow or at the bottom interface of the storm snow where a weaker layer may exist.

Be alert to conditions that change with elevation and use caution in wind loaded northwest to east facing terrain. >Use conservative route selection, stick to moderate angled terrain with low consequence.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 6

Persistent Slabs

There is potential for heavy loads like a cornice fall or a storm slab avalanche to step down and trigger a deeper persistent weak layer, down over 1m in most places.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid lingering in runout zones.>

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Mar 11th, 2014 2:00PM