Avalanche Forecast

Issued: Mar 18th, 2014 9:22AM

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

bcorrigan, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

Synopsis: A low pressure system in the North Pacific continues to feed moisture into BC .Tonight: Cloudy with flurries, possible 5 to 10 cm of precipitation, freezing level around 500 metres, winds from the west, light, occasionally gusting to strong.Wednesday: Cloudy with flurries, trace of precipitation, freezing level around 700 metres, ridge top winds light from the west, gusting to moderate.Thursday: Cloudy with sunny periods and flurries, trace amounts of precipitation, freezing level around 700 metres, light ridge top winds..Friday: Cloudy with flurries, 5 to 10cm of precipitation, freezing level around 500 metres, winds from the southeast, light to moderate at ridge tops.

Avalanche Summary

Reports indicate the Feb.10th weak layer has been re-activated with recent new snow loading.Â Commercial operators have reported a widespread natural cycle in the past 24 hrs, and on Sunday a skier controlled size 2 was triggered on the Feb. 10th weak layer, on a north aspect at 1100 metres in the Hankin area. Conditions are primed for rider and sledder triggered avalanches!

Snowpack Summary

Conditions are highly variable throughout the forecast region, with considerably more snow to the west and north. An additional 10 cm of recent storm snow in the Hudson Bay Mtn. area brings the slab to between 40 and 80cm overlying the early March weak layer of surface hoar and/or a layer of faceted snow. This layer is most likely present on protected north slopes at all elevations. There is a sun crust on steep solar aspects, and various wind affected surfaces in exposed terrain. Strong winds have created dense wind slabs on exposed lee slopes and in cross-loaded features. In wind exposed areas, the snow surface is reported to be wind scoured and may have a supportive wind-pressed slab. Moist/wet snow, rain crust or melt-freeze crusts in the upper snowpack are likely, below 1200m. The early February weak layer of facets, crusts, and/or surface hoar is buried down about 60-100 cm. Test results and recent avalanche activity suggest this layer is still reactive to human-triggering. Basal facets and depth hoar remain a concern in areas with thin or variable snow cover.

Problems

Storm Slabs

The recent storm snow sits on a variety of surfaces, from rain and temperature crusts at lower elevations, to wind scoured surfaces around tree line and in the alpine, with wind slabs on lee slopes. Rider triggering is easily possible right now.

Choose well supported terrain without convexities.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 4

Persistent Slabs

The Feb. and March persistent weak layers appear to have been re-awakened by new snow loads and might now be triggered by light loads like skiers and sledders The slab is now typically 40 to 80 cm thick and continues to produce large avalanches.

Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Deep Persistent Slabs

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

Valid until: Mar 19th, 2014 2:00PM