Avalanche Forecast

Issued: Mar 6th, 2018 4:58PM

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

Avalanche Canada shorton, Avalanche Canada

Lingering wind slabs and cornices are a concern at higher elevations. Also be aware of direct sunlight weakening the surface snow on south-facing slopes.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

WEDNESDAY: Sunny in the morning with increasing clouds in the afternoon, light to moderate southwest wind, freezing level rising to around 1500 m.THURSDAY: Flurries increasing throughout the day with up to 5 cm in the north and up to 10 cm in the south, moderate southwest wind, freezing level rising to around 1300 m.FRIDAY: Another 5-10 cm of snow with freezing level rising to around 1300 m.

Avalanche Summary

On Monday, a few small slabs (10-20 cm deep) were reported in steep terrain in the northern part of the region. Over the weekend, a few size 2 natural slab avalanches were reported in the northern part of the region on a range of aspects around 2000 m.

Snowpack Summary

A thin sun crust has formed on solar aspects and the surface is wind affected in most exposed terrain. Southern parts of the region, such as the Coquihalla, received up to 100 cm of snow last week while northern regions received closer to 40 cm.The mid-February weak layers are now 80 to 120 cm deep in the southern part of the region and about 40 cm deep in northern parts of the region. These interfaces consists of wind hardened snow, facets, a sun crust on solar aspects, and surface hoar that is present at and below treeline. Some of these layers have been reactive in snowpack tests, but no recent avalanche activity has been reported on these layers. The mid and lower snowpack are well settled and strong.Variable winds in the past month have created cornices on many alpine ridgelines. They will become touchier as they grow in size, as temperatures rise, and as the strong late-winter sun shines down upon them on clear days.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent variable winds have left behind slabs in the lee of ridges and ribs.
Use ridges or ribs to avoid pockets of wind loaded snow.Be alert to conditions that change with elevation.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Cornices

An icon showing Cornices
Continued snowfall and strong wind from around the clock has formed large cornices on many ridgelines. Cornices are inherently unstable, unpredictable, and demand respect, especially when the sun is out.
Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.Watch out for overhead hazards, such as cornices, which could trigger slabs on slopes below.Give cornices a wide berth when travelling on or below ridges.

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Mar 7th, 2018 2:00PM

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