Avalanche Forecast

Issued: Mar 14th, 2014 9:58AM

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

rbuhler, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The next storm system is expected to reach the north coast on Saturday morning. Light precipitation and strong winds are expected for the inland region on Saturday and Sunday. Conditions should be milder to the north of the region. A weak ridge of high pressure should build on Monday.Saturday: Precipitation 5-10mm, freezing levels am: 600m pm: 1200m, ridgetop wind 40-60 km/h S-SWSat. Night/Sunday: Precipitation 5-15mm, freezing levels am: 1200m pm: 1000m, ridgetop wind 40-60 km/h S-SW Monday: Dry or light flurries, freezing levels am: 300m pm: 600m, ridgetop wind light SW-W

Avalanche Summary

A natural cycle was reported to have occurred on Wednesday. Activity tapered off on Thursday. The focus of the activity seems to be primarily wind slabs or storm slabs sitting over the early-March weak layer. Some of these smaller avalanches have stepped down to the deeper February weak layer creating larger, more destructive avalanches.

Snowpack Summary

Conditions are reported to be highly variable. Roughly 30-60 cm of snow now sits on a weak layer consisting of surface hoar and/or a thick layer of faceted snow on shady slopes at all elevations, 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

New snowfall and strong winds will add to the existing slab that sits on the early March weak layer. Strong forecast SW winds should quickly form new wind slabs or add to existing wind slabs on leeward aspects.

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

Deep Persistent Slabs

The weak layer from early-Feb is typically down 60-100cm. The problem is becoming more isolated and triggering is becoming more difficult. However, the layer is still reactive in places and has the potential to produce large, destructive avalanches.

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

Possible

Expected Size

3 - 6

Valid until: Mar 15th, 2014 2:00PM