Avalanche Forecast

Issued: Mar 12th, 2014 9:58AM

The alpine rating is considerable, 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

Thursday should be relatively dry before the next frontal system reaches the coast on Thursday evening. Light precipitation is expected for the inland region on Friday and Saturday. Greater amounts are expected for the south of the region.Thursday: Cloudy, dry conditions during the day, snowfall in the evening, freezing level am: 500m pm: 900m, ridgetop wind light S-SWThurs. Night/Friday: Snowfall 5-15cm, freezing level am: 600m pm: 1200m, ridgetop wind 30-50 km/h S-SWSaturday: Snowfall light to moderate, freezing level am: 500m pm: 1000m, ridgetop wind light to moderate S-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.

Snowpack Summary

Roughly 40-60 cm of dense 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.

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 still has the potential to produce large, destructive avalanches.

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

Expected Size

3 - 6

Valid until: Mar 13th, 2014 2:00PM