Avalanche Forecast

Issued: Mar 16th, 2017 4:52PM

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

cgarritty, Avalanche Canada

Northwest Inland.

Wind slabs have emerged as the primary avalanche problem in the region, but they aren't the only one. Our deep persistent slab problem lingers on.

Summary

Confidence

Moderate -

Weather Forecast

Friday: Mainly cloudy with scattered flurries and a trace to 5 cm of new snow. Strong southeast winds. Alpine temperatures of -7. Saturday: A mix of sun and cloud with isolated flurries and a trace of new snow. Light to moderate west winds. Alpine temperatures of -8. Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Moderate to strong west winds. Alpine temperatures of -9.

Avalanche Summary

A report from the north of the region details a remotely triggered Size 2 storm slab releasing on a northeast aspect at 1400 metres on Wednesday. The slab depth was 50 cm. Numerous natural avalanches up to size 2.5 were reported from the west of the region in the Howsons on Tuesday. Natural avalanches up to size 2.0 were reported from the Hankin area on Monday.

Snowpack Summary

As our recent snow has formed a bond to the surface, ongoing winds and light new snow amounts have seen wind slabs emerge as the primary avalanche problem in the region. At lower elevations, below zero temperatures on Wednesday night likely led to a surface crust forming over previously reported moist or wet snow. At higher elevations where new snow has been accumulating, a weak interface that was buried in late February may finally have enough snow above it to form a reactive slab. The interface is composed of facets, crusts, and surface hoar and may be 40-60 cm deep. There's uncertainty about the distribution and reactivity of this interface. The mid-pack is well consolidated, but sits above weak sugary snow near the ground. This deeper basal weakness remains an ongoing concern in thin rocky start zones and in shallow snowpack locations.

Problems

Wind Slabs

Forecast flurries will combine with strong south to southeast winds and form fresh wind slabs on Friday. Use increasing caution as you enter wind affected terrain expect touchy new slabs in the lee of exposed terrain features at treeline and above.

Be alert to conditions that change with elevation.Be increasingly cautious as you transition into wind affected terrain.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

A lingering weakness at the bottom of the snowpack is here to stay. It will be most reactive in thin rocky start zones and in shallow snowpack locations.

Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.If triggered, wind slabs may step down to deeper layers and result in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 17th, 2017 2:00PM