Avalanche Forecast

Issued: Jan 8th, 2015 8:14AM

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

rbuhler, Avalanche Canada

Northwest Coastal.

Lingering storm instabilities remain a concern. Investigate local conditions in your area before committing yourself to avalanche terrain.

Summary

Confidence

Fair

Weather Forecast

The warm air should break down on Friday. Freezing levels will progressively fall to around 1000m by Friday night. Mostly cloudy conditions are expected during the day and alpine winds are expected to be moderate from the S-SW. On Friday night, a weak trough crosses the north coast and 5-10cm of new snow is possible in many parts of the region. On Saturday, mostly cloudy conditions, light flurries, and light alpine winds are expected. Freezing levels should be around 800m. Sunday should see a mix of sun and cloud, light alpine wind, and freezing levels around valley bottom.

Avalanche Summary

On Wednesday, two natural size 2.5 wind slab avalanches were reported.Â These occurred on NW-N aspects at around 1600m elevation.Â Explosives released several wind slabs sized 2-3.Â On Tuesday, several natural size 2 avalanches were reported in the Terrace area. Natural avalanches activity is generally not expected on Thursday but isolated natural avalanches remain possible. The potential for human triggering is still a major concern for Friday.

Snowpack Summary

Storm snow amounts vary across the region. Since the weekend, some southern areas received close to 1m of new snow and northern areas probably around half that. Strong winds are one common theme in all areas though. Ridge winds were cranking from the SE-SW stripping windward slopes bare and probably forming hard or dense wind slabs in lee and cross-loaded areas. Warm air in the alpine may be melting the snow surface and a surface crust may form when the warm air exits.Â A buried surface hoar layer in the mid-snowpack may be most prevalent in northern sections like Bear Pass and Ninginsaw Pass. The mid December crust can also be found in the middle of the snowpack and is sandwiched with facets and surface hoar. The November crust down near the bottom of the snowpack is generally well bonded but is still reactive in some test profiles.

Problems

Storm Slabs

Heavy snowfall and strong winds have built both storm slabs and wind slabs in the south of the region. In the northern areas that received less snowfall, wind slabs are the primary concern.

Avoid steep, open slopes.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Loose Wet

Warm air and periods of sun may destabilize the snow surface. Sluffing is expected from steep sunny slopes and have the potential to trigger larger slab avalanches.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious of sluffing in steep terrain.>

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

There are a couple persistent weak layers in the middle of the snowpack. Heavy triggers like cornice falls or smaller avalanches have the potential to trigger one of these deeper layers. These layers were most reactive in the north of the region.

Use caution around convexities, ridge crests, rock outcroppings and anywhere else with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Jan 9th, 2015 2:00PM