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Archived

Avalanche Forecast

Jan 28th, 2019–Jan 29th, 2019
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

Conditions are highly variable from north to south within the Northwest Coastal region. In the southern portion of the region, near Terrace and Kitimat, the hazard in the alpine is likely moderate.

Confidence

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

Weather Forecast

MONDAY NIGHT - Clear periods / light southerly winds / alpine low temperature near 0 / alpine temperature inversion TUESDAY - Mainly cloudy with flurries beginning in the afternoon / light southwest winds / alpine high temperature near +2 / alpine temperature inversionWEDNESDAY - Periods of snow, 10-15 cm / southwest winds 20-50 km/h / alpine high temperature near -2 THURSDAY - Periods of snow, 15-20 cm / south winds, 10-20 km/h / alpine high temperature near -1

Avalanche Summary

A widespread natural avalanche cycle to size 3.5 was reported on all aspects north of Stewart on Sunday. There were also two human triggered avalanches reported in this area on Sunday, one size 2 and one 2.5. These occurred on southerly aspects between 1500-1800 m.In the south of the region, closer to Terrace, there were reports of a natural avalanche cycle to size 3 in high alpine terrain on Sunday.On Saturday, observations were limited due to the ongoing storm. Several explosives triggered avalanches to size 2.5 were reported, and it is likely that a widespread natural avalanche cycle was occurring as well.

Snowpack Summary

Up to 40 cm of recent storm snow sits on a weak layer of surface hoar (feathery crystals), and a crust on sun-exposed slopes. The highest amounts of this new snow are north of Stewart and taper significantly as you head south.The recent precipitation fell mainly as rain below about 1200 m in the north and below about 1600 m in the south.In some areas, there is another layer of surface hoar that is now buried 50-70 cm. A weak layer of facets (sugary snow) buried in early December exists down 180-250 cm.Avalanches triggered within the new snow have the potential to step down to these deeper layers, resulting in very large avalanches.

Avalanche Problems

Storm Slabs

Storm slabs may still be reactive to human triggers, especially in wind loaded areas. Warm temperatures will also promote reactivity.
Watch for whumpfing, hollow sounds, and shooting cracks.If triggered, storm slabs may step down to deeper layers and result in even larger avalanches.Be especially careful around thick, wind-loaded pockets near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Persistent Slabs

Recent snowfall and warm temperatures have added load and stress to a weak layer of surface hoar (feathery crystals) now buried approximately 50-60 cm deep.
Use conservative route selection, choose moderate angled and supported terrain with low consequence.Watch for signs of instability such as whumpfing, or cracking, or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1.5 - 3