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Avalanche Forecast

Dec 31st, 2018–Jan 1st, 2019
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
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
1: Low
The avalanche danger rating below treeline will be low

Regions: South Coast Inland.

A conservative approach to terrain selection is recommended at the tree line elevation band in the south of the region. A recently buried weak layer has been the culprit in several avalanche incidents around Coquihalla Summit and Manning Park.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

TUESDAY: Mainly cloudy with isolated flurries / Light southwest wind / Alpine temperature -4 C WEDNESDAY: Flurries / Light to moderate southwest wind / Alpine temperature -1 C / Freezing level 1000 mTHURSDAY: Snow, accumulation 10-20 cm / Moderate to strong southwest wind / Alpine temperature 0 C / Freezing level 1600 m

Avalanche Summary

There were several reports of skier and snowmobile triggered avalanches on Sunday. There was a report of two skier triggered avalanches in the Zoa peak area near Coquihalla Summit. These were both reported to be up to size 2 and running on a layer of surface hoar buried 40-60cm deep on a north aspect at tree-line. See the MIN report here. An additional avalanche incident was reported by some snowshoers in Manning Park. It is suspected to have run on the same weak layer. See the MIN report here.

Snowpack Summary

20-30 cm of recent new snow is covering what is reported to be a widespread weak layer of feathery surface hoar. This newly buried weak layer is reported to be most prevalent at the upper end of treeline on north and east aspects in the southern portion of the region near Coquihalla Summit and Manning Park. Expect the deepest deposits of storm snow to be in lee and cross-loaded terrain features.In the north portion of the region and possibly the far south, a weak layer of facets and/or surface hoar is buried around 100 to 150 cm deep. The weak layer appears most prominent around treeline, up to 2000 m. There has not been reports of avalanche activity on this layer for the past week. Although this layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists.

Avalanche Problems

Storm Slabs

New snow combined with wind has promoted the development of storm slabs that may be sitting on a weak layer of feathery surface hoar. Thickest deposits can be found in the lee of terrain features.
Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2