Avalanche Forecast

Issued: Apr 1st, 2014 10:12AM

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

ghelgeson, Avalanche Canada

Northwest Coastal.

Summary

Confidence

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

Weather Forecast

Synopsis: A frontal system approaches the North Coast on Wednesday leading to clouds and precipitation developing Wednesday afternoon. Light/locally moderate snowfall is expected through the forecast period.Wednesday: Freezing Level: 500m - 1100m; Precipitation: 2:11mm - 2:15cm; Wind: Treeline: Light, SW | Ridgetop: Moderate, SWThursday: Freezing Level: 600m - 1200m; Precipitation: 2:9mm - 2:10cm; Wind: Treeline: Strong, S | Ridgetop: Extreme, SWFriday: Freezing Level: 800 - 1300m Precipitation: 1:5mm - 1:7cm; Wind: Treeline: Light, SW | Ridgetop: Strong, W

Avalanche Summary

A large rock fall event on a north facing alpine feature initiated a size 3.5 avalanche that failed on the early February persistent weak layer. Several smaller loose snow avalanches to size 2 were running in the recent storm snow on steep solar aspects too.

Snowpack Summary

It's starting to feel like spring in the NW. Valley temps are creeping into the double digits during the day, and there are reports of the top 15 cm of the snowpack becoming moist during daytime heating.The last significant shot of snow was on March 27th, 10 - 15 fell on March 30th. This new snow rests on top of a haggard old surface composed of old wind slab, melt freeze crust, and faceted old snow. Ongoing melt freeze cycles will likely help to heal any surface instabilities.The early March layer can be found down 75 - 100cm and is composed of facets/surface hoar on shady aspects and facets/crust on southerly aspects. I suspect this layer has been the culprit in the human triggered avalanches from March 27/28 that are being reported on the Balktalk Facebook Page.The early February crust/facet/surface hoar combo is down 150 - 200cm, and I suspect it's gone mostly dormant for now.

Problems

Wind Slabs

While the old hard wind slabs are unlikely to be triggered at this point, fresh shallow wind slabs may be found immediately lee of ridge crest and mid slope features.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Deep Persistent Slabs

At this point the deep persistent weak layers would likely require a specific trigger like cornice fall, a surface avalanche in motion, or a rider finding the sweet spot, to be activated.

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.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 2nd, 2014 2:00PM