Avalanche Forecast

Issued: Mar 3rd, 2014 8:34AM

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

jlammers, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Overview: A series of disturbances are embedded in a west/southwesterly flow which will bring continued snowfall to the region. There is some model disagreement in the track and timing of the systems; however, southern parts of the region are generally expected to see the highest accumulations.Monday night: Up to 20cm of snow / Strong southwest winds / Freezing level at surfaceTuesday: Light snowfall / Moderate to strong westerly winds / Freezing level at surfaceWednesday: 10-20cm of snow / Light ridgetop winds / Freezing level at about 500mThursday: Light flurries / Moderate to strong southwest winds / Freezing level at about 1000m

Avalanche Summary

Over the weekend 2 size 2 skier-triggered avalanches (1 was remotely triggered from 25m) occurred in the Monashees. The February 10th interface was the culprit in these events. A few remotely triggered size 1 hard wind slabs were also noted over the weekend in exposed lee terrain. They formed in response to strong winds and redistribution of surface snow on Friday night. I would expect fairly widespread storm slab avalanche activity with ongoing snowfall and wind.

Snowpack Summary

In many areas over 40cm of storm snow overlies surface hoar in sheltered areas, a sun crust on solar aspects and wind slabs in exposed terrain. Initially, these new accumulations are expected to react as a wind slab in exposed terrain. As the new slab deepens and gains cohesion by wind and warming, more widespread storm slab activity can be anticipated.There is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies between 80 and 130cm below the surface, and includes surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. Although avalanche activity at this interface has generally tapered-off, large destructive avalanches are still a very real concern with recent reports of remote-triggering, "whumpfing" and sudden snowpack test results. For the most part, the mid and lower snowpack are strong and well consolidated.

Problems

Storm Slabs

Continued snowfall and wind will add to a developing slab which overlies a variety of potentially weak surfaces. Watch for increased slab reactivity in wind exposed terrain. In sheltered, steep terrain the new snow may react as a loose dry avalanche.

Be cautious as you transition into wind affected terrain.>The new snow will require several days to settle and stabilize.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

A deep, dense slab overlies a variety of weak layers and may still be touchy in some areas. Triggering this weakness would have nasty consequences, so don't let the lure of powder tempt you into large, unsupported terrain.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Avoid convexities or areas with a thin or variable snowpack.>Avoid areas with overhead hazard.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Mar 4th, 2014 2:00PM