Avalanche Forecast

Issued: Mar 15th, 2017 3:40PM

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

triley, Avalanche Canada

Northwest Inland.

Storm slabs continue to develop with each pulse of new snow and wind.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight: Freezing level down to valley bottoms, 2-3 cm of new snow, moderate southwest winds. Thursday: Daytime freezing level around 700 metres, 3-5 cm of new snow, moderate southwest winds, and a chance of sunny periods in the afternoon. Friday: Daytime freezing level around 500 metres, 2-3 cm of new snow, moderate southwest winds. Saturday: Daytime freezing level around 500 metres, 3-5 cm of new snow, moderate southwest winds.

Avalanche Summary

Numerous natural avalanches up to size 2.5 were reported from the west of the region in the Howson's on Tuesday. Natural avalanches up to size 2.0 were reported from the Hankin area on Monday.

Snowpack Summary

Storm slabs continue to build with each pulse of snow and wind. Warm temperatures will make touchy slabs at higher elevations and unstable wet snow at lower elevations. 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 and sits above weak sugary snow near the ground. The deeper basal weakness remains a concern in thin rocky start zones and shallow snowpack locations.

Problems

Storm Slabs

Storm slabs are expected to continue to develop due to forecast new snow and wind. Watch for the transition to moist or wet snow as you descend in elevation.

Minimize exposure during periods of heavy loading from new snow and wind.Use conservative route selection, stick to moderate angled terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A reactive slab has possibly formed above a weak layer of crusts, facets, and surface hoar that formed in February. This weak layer may be spotty and confined to terrain that is sheltered from the wind.

Choose well supported terrain without convexities.Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Deep Persistent Slabs

A lingering weakness at the bottom of the snowpack may reawaken with the load of the new snow and warming. It'll be most reactive in thin rocky start zones and shallow snowpack locations.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 16th, 2017 2:00PM