Avalanche Forecast

Issued: Nov 25th, 2017 4:51PM

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

cgarritty, Avalanche Canada

Northwest Coastal.

Avalanche danger is increasing as new snow and strong winds incrementally load the snowpack. Reports from higher elevations have been limited and it remains essential to supplement this forecast with your own observations and safe travel techniques.

Summary

Confidence

Low - Forecast snowfall amounts are uncertain

Weather Forecast

Sunday: Flurries bringing 5-15 cm of new snow. Moderate to strong south winds. Freezing level to 1000 metres with alpine temperatures of -3.Monday: Periods of snow bringing approximately 15 cm of new snow, increasing over the day. Strong south winds. Freezing level to 1000 metres with alpine temperatures around -2.Tuesday: Flurries brining 10-15 cm of new snow. Moderate to strong southwest winds. Freezing level around 1000 metres with alpine temperatures around -2.

Avalanche Summary

Reports from Wednesday included observations of several natural wind slab releases from steep, north-facing alpine terrain in Bear Pass. These were triggered by rain. Reports from Sunday showed evidence of a natural loose wet avalanche cycle focused on steep, low elevation rock slabs along Highway 16 between Terrace and Prince Rupert. Observations of high elevation terrain have been very limited. Please post your observations to the Mountain Information Network (MIN)

Snowpack Summary

Snowpack depths at treeline elevations average about 70-130 cm in the south of the region. Here, an elevation dependant 20-40 cm of new snow from last week's storm now forms the upper snowpack. Moderate to strong alpine winds during and since the storm encouraged the formation of storm slabs in the new snow. These slabs will increase in size and sensitivity in wind-exposed areas. A thick rain crust that formed early last week exists below the new snow and has produced hard results in snowpack tests. Below this crust, two weak layers are noted to have formed during the early season. (October 31 and November 11). The deeper late October layer has produced moderate to hard results in targeted snowpack tests. Beneath it, the bottom 20 cm of the snowpack features loose, sugary crystals that have begun to show signs of improved bonding. Looking further to the north of the region near Ningunsaw, the snowpack is starkly different. Here, much drier, colder early season conditions produced a shallow snowpack composed mainly of weak, sugary snow. Snow depths in this part of the region are largely below threshold depths for avalanching.

Problems

Storm Slabs

Stormy weather is continuing to build touchy new storm slabs at upper elevations. Slab size and reactivity will increase with elevation. A storm slab release may have the potential to step down to deeper weak layer to produce a very large avalanche.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.The new snow will require several days to settle and stabilize.If triggered, storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

As snow stacks up at higher elevations, rain has saturated much of the snowpack below treeline. Danger from loose wet avalanches exists where surface snow remains moist - especially in steep terrain.

Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Nov 26th, 2017 2:00PM