Avalanche Forecast

Issued: Mar 23rd, 2017 3:00PM

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

shorton, Avalanche Canada

Northwest Coastal.

The persistent slab problem still needs time to stabilize. Evaluate the terrain and snowpack carefully and stay aware of overhead hazards.

Summary

Confidence

High - Due to the number and quality of field observations

Weather Forecast

FRIDAY: Unsettled weather with flurries bringing 5-10 cm of snow, moderate south wind, alpine temperature around -3 C.SATURDAY: More flurries with another 10-15 cm, strong south wind, alpine temperature around -6 C.SUNDAY: Lingering flurries, moderate southeast wind, alpine temperature around -6 C.

Avalanche Summary

No new avalanches were reported on Wednesday, but 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 and 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 the previous day, including a size 3 avalanche that was remotely triggered from flat terrain by a snowmobiler north of Stewart.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 and cornices are forming in the lee of exposed terrain as unsettled weather brings small amounts of new snow and moderate winds. Recent warming and sun have likely left a crust on solar aspects and below 1000 m. Snow may still be poorly bonded to a 40 cm deep crust and surface hoar interface from mid-March, however, the late-February interface has been the more troublesome persistent layer. It's composed of facets, crust, and surface hoar roughly 50-100 cm deep and is still reactive throughout the region, especially in shallower areas around Stewart and Bear Pass.

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.

Avoid unsupported slopes.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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.

Remote triggering is a concern, watch out for adjacent slopes.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 24th, 2017 2:00PM