Avalanche Forecast

Issued: Mar 17th, 2014 9:44AM

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 Gulf of Alaska continues to feed moisture onto the coast for the next 4 or 5 days, but not much is expected to make it to the interior.Tonight: Cloudy, no precipitation in the forecast, freezing level around 500 metres winds from the south light occasionally gusting to moderate.Tuesday: Cloudy with a possible 10 cm of precipitation, freezing level around 1100 metres, winds from the south west light occasionally gusting moderate to strong.Wednesday: Cloudy with flurries, another possible 10cm of precipitation expected, freezing level at valley bottom, ridge top winds light from the west, gusting to moderate.Thursday: Cloudy with sunny periods and possible flurries, trace amounts of precipitation, freezing level around 800 metres, winds light occasionally gusting to moderate.

Avalanche Summary

Reports indicate the Feb.10th weak layer has been re-activated with recent new snow loading, 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 right now !

Snowpack Summary

Conditions are highly variable throughout the forecast region. 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 thick layer of faceted snow. This layer is most likely present on shady slopes at all elevations. There is a sun crust on steep solar aspects, and various wind affected surfaces in exposed terrain. Strong southwest 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 or a very supportive wind-pressed slab. Moist/wet snow or melt-freeze crusts in the upper snowpack are likely at lower elevations, below roughly 1200m. The early February weak layer of facets, crusts, and/or surface hoar is buried down about 60-100 cm. Test results and isolated 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 crust 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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 4

Persistent Slabs

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Deep Persistent Slabs

There have been recent reports of avalanches on this deep persistent layer. Use caution in shallow snowpack areas.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

Valid until: Mar 18th, 2014 2:00PM