Avalanche Forecast

Issued: Mar 8th, 2014 7:29AM

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

Peter, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Tonight and Sunday: Periods of snow 20-30 cm. The freezing level is around 600-800 m. Winds are strong easing to moderate from the W-SW. Monday: Cloudy with sunny breaks and possible flurries. The freezing level is around 800 m. Winds are light but gusty from the W-SW. Tuesday: Periods of snow, heavy at times. The freezing level is around 1200-1500 m and winds increase to strong from the SW.

Avalanche Summary

Numerous size 1-2 rider triggered slab avalanches were reported throughout the region on Friday. It's likely a fairly widespread natural avalanche cycle occurred in many areas later on Friday afternoon when the storm peaked. Expect natural avalanche activity to taper off over the next couple days, while the potential for rider triggering remains high.

Snowpack Summary

40-70 cm of storm snow now sits on a layer of surface hoar or sugary faceted snow on shady slopes, a sun crust on steep solar aspects, or hard wind slabs and scoured slopes in exposed terrain. Initial tests on this new interface showed a poor bond between the new snow and old snow surface. Weaknesses may also exist within the new storm snow. The mid February weak layer of surface hoar or a crust/facet combo is buried 60-120 cm deep. There has been no reported activity on this layer recently, but the recent heavy snowfall and rapid warming could have triggered some large avalanches. Basal facets and/or depth hoar remain a concern in shallow snowpack areas in the northern part of the region.

Problems

Storm Slabs

Weather models suggest we will see another 20 cm through Sunday. This adds to the 30-60 cm that fell on Friday. All this snow sits on the previous old snow surface of facets, surface hoar, and/or a crust and may not bond well.

Stick to non-avalanche terrain or small features with limited consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - 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 a metre 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: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 7

Valid until: Mar 9th, 2014 3:00PM