Avalanche Forecast

Issued: Dec 19th, 2013 8:22AM

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

ghelgeson, Avalanche Canada

Northwest Coastal.

Forecast snow amounts vary widely across the region with the more western portions receiving the greatest amounts. If your location receives less than 20 cm Thurs night/Fri, these danger ratings are likely one level too high.

Summary

Confidence

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

Weather Forecast

Synopsis: Upper NW flow brings significant snow and wind to the North Coast Friday. Saturday offers a break in the action before another wave of warm air moves in late Sunday.Thursday evening: Freezing Level: Surface Precip: 5-20mm 10/30cm with more coastal locations receiving greater accumulations.Friday: Freezing Level: 200m Precip: 2/5mm 4/10cm Wind: Lht gusting Strong, W Saturday: Freezing Level: 1000m Precip: Beginning Saturday night 10/20mm 20/30cm Wind: Lht gusting Strong, WSunday: Freezing Level: 2000m Precip: 20/40mm Wind: Mod gusting Extreme, SW

Avalanche Summary

Avalanche activity slowed down a bit on Thursday, likely due to the cooler temperatures. Earlier this week numerous size 2-3 avalanches were running naturally and with explosive assistance throughout the region on all aspects with the bulk of the activity occurring on N - SE facing aspects.

Snowpack Summary

Total snowpack depth in the region ranges between 140 - 200cm. A surface hoar/facet combo formed during the early December cold snap is now buried 50 - 80cm below the surface. In some locations this layer rests on an old melt freeze crust. The last storm came in wet & heavy with the freezing level as high as 1500m at times. Strong south and west winds during and just after the last storm resulted in widespread wind slab formation.The mid pack is composed of various faceted layers and crusts. A significant crust/facet combo lingers near the base of the snowpack.

Problems

Storm Slabs

Coastal locations could see as much as 30 cm of new snow Thursday night. The more interior portions of the region should receive less snow. New snow will bury recently formed wind slabs that will likely remain sensitive to human triggering.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Deep Persistent Slabs

Deep persistent avalanches will likely increase in sensitivity to human triggering with increased load in the form of new snow. It's time to reign the terrain choices way back this weekend.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be aware of the potential for large, deep avalanches due to the presence of deeply buried weak layers.>Choose simple well supported terrain free of: overhead hazard, thin spots and convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 6

Valid until: Dec 20th, 2013 2:00PM