Avalanche Forecast

Issued: Mar 13th, 2014 9:28AM

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 hits the north coast on Thursday night or Friday morning. A bit of a break is expected for Friday night before the second system arrives Saturday morning. The second system is expected to be stronger and should last until Sunday night. The south of the region can expect greater snowfall amounts than the north. There is a fair amount of uncertainty regarding freezing levels.Thurs. Night/Friday: Snow 5-15cm, freezing levels up to ~1200m, ridgetop wind 30-40 km/h S-SWSaturday: Light to moderate snowfall, freezing levels up to ~1000m, ridgetop wind 20-40 km/h SE-SWSunday: Light to moderate snowfall, ridgetop wind 30-50 km/h SW

Avalanche Summary

A natural cycle to size 1 is being reported in the south of the region on Wednesday. In the north, a natural cycle is also reported for Tuesday/Wednesday and the typical avalanche size is expected to be larger than in the south. The NW Coastal region saw widespread natural activity up to size 4 on Wednesday.

Snowpack Summary

Roughly 40-60 cm of storm 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. 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

Up to 60 cm of dense storm snow overlies a weak layer of facets, old wind slabs, and/or a melt-freeze crust. Strong wind, typically from the SW, has created stiffer wind slabs in lee features.

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

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 still 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 open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 14th, 2014 2:00PM