Avalanche Forecast

Issued: Dec 16th, 2017 4:53PM

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

ghelgeson, Avalanche Canada

Northwest Coastal.

The storm surges on! Continue to avoid all avalanche terrain on Sunday during periods of heavy loading from rain, new snow and wind.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Sunday

Weather Forecast

A frontal system impacting the coast is expected to continue to deliver moderate precipitation and strong southwest wind through Saturday night. Continued snow and wind in more modest quantities is expected on Sunday and Monday before the ridge rebounds on Tuesday. SATURDAY NIGHT: Freezing level 1400m at sundown, decreasing through the night. 10 to 25cm of snow possible, strong to extreme southwest wind.SUNDAY: Overcast, freezing level around 600m, moderate to strong west/southwest wind, 3 to 15cm of snow. MONDAY: Overcast, freezing level around 500m, moderate to strong southwest wind, 2 to 10cm of snow. TUESDAY: Scattered cloud cover, freezing level at valley bottom, light variable wind, no new snow expected.Visit avalanche.ca/weather for a more detailed mountain weather forecast.

Avalanche Summary

On Friday wet slab avalanches to size 2 were reported from steep terrain where the ground cover consists of smooth rock slab. These avalanches went to ground. It is suspected that natural avalanche activity continued through the day Saturday.

Snowpack Summary

The region picked up 15 to 40cm of storm snow Friday evening into Saturday morning, and new snow fall continues to fuel storm slab development as of Saturday afternoon. These new storm slabs rest on a rain saturated snowpack between valley bottom and 800m. Above 800m the new storm snow rests on settled old snow, or a variable melt freeze crust. In some areas a feathery surface hoar layer down 50 to 60cm was producing moderate snowpack test results. Down 70 to 100cm lies a 5 to 10cm thick crust which was buried on November 23rd. There is a second crust that is associated with facets that was buried at the end of October, look for this widespread interface down around 100 to 200cm below the surface.

Problems

Storm Slabs

Continued snow and wind is expected to prolong the ongoing natural avalanche cycle on all aspects and elevations. Wet loose avalanches may occur from steeper terrain features below treeline too.

The new snow will require several days to settle and stabilize.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

1 - 3

Deep Persistent Slabs

As new snow and wind is added to the snowpack, the chance of awakening more deeply buried weaknesses near the base of the snowpack increases.

Take extra caution around areas with a thin or variable snowpack.Minimize exposure to overhead avalanche terrain, large destructive avalanches are possible.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 17th, 2017 2:00PM