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Avalanche Forecast

Mar 22nd, 2017–Mar 23rd, 2017
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
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
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.

Wind slabs are growing while a deeper weakness continues to produce large avalanches. Evaluate the terrain and snowpack carefully and stay aware of overhead hazards.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

THURSDAY: Unsettled weather with flurries bringing 5-15 cm of snow, moderate and gusty south wind, alpine temperature around -6 C.FRIDAY: More flurries with 5-15 cm, moderate south wind, alpine temperature around -4 C.SATURDAY: Still more flurries with 5-15 cm, moderate southwest wind, alpine temperature around -6 C.

Avalanche Summary

Reports from Tuesday indicate the persistent slab problem is alive and well throughout the region. A few natural size 2-2.5 avalanches were triggered in the Bear Pass / Stewart area by solar input or cornices. A skier also remotely triggered a size 2 avalanche on the February facet/crust interface on a moraine feature around 1150 m (40 cm deep). Similar activity was reported on Monday, including a size 3 avalanche that was remotely triggered from flat terrain by a snowmobiler north of Stewart. Smaller natural avalanches were also reported on Tuesday, including size 1-2 wind slabs from recent wind loading and size 1.5-2 loose moist avalanches in steep solar-facing terrain.In addition to the ongoing persistent slab problem, the incoming weather pattern is looking to continually build fresh wind slabs.

Snowpack Summary

Fresh wind slabs are forming in the lee of exposed terrain as unsettled weather brings small amounts of new snow and moderate southwest winds. Storm snow from last week is continuing to settle and get redistributed by predominately southerly winds. Old wind slabs may be reactive above a 40 cm deep rain crust. At treeline and above, recent loading has stressed a 50-100 cm deep weak interface composed of facets, crust, and surface hoar from late February. Recent reports suggest this layer is still reactive throughout the region, especially in the north.

Avalanche Problems

Wind Slabs

A steady pulse of unsettled weather will build fresh wind slabs in the lee of exposed terrain. Recent winds have also built touchy cornices.
If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Avoid unsupported slopes.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

A weak facet/crust layer from late February has produced several large human triggered avalanches the past few days. Triggering this layer is most likely in shallower areas, but a small wind slab or cornice fall could act as a natural trigger.
Avoid steep convexities or areas with a thin or variable snowpack.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Remote triggering is a concern, watch out for adjacent slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 3