Avalanche Forecast

Issued: Mar 10th, 2014 9:27AM

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

rbuhler, Avalanche Canada

Northwest Inland.

Summary

Confidence

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

Weather Forecast

A Pacific frontal system will arrive on the North Coast Tuesday morning. While the coast can expect substantial precipitation for Tuesday and Wednesday, it does not look like much will push into the inland region. Thursday is expected to be dry.Tuesday: Snow or rain 2-4mm, freezing level 300-600m overnight, 1400m afternoon, ridgetop winds 50-70 km/h SWTues. Night/Wednesday: Snow or rain 3-6mm, freezing level 1400m overnight, 1200m in the afternoon, ridgetop winds 50-70 km/h SW, easing in the afternoonThursday: A mix of sun and cloud, dry conditions, freezing level 400m overnight, 1000m afternoon, ridgetop winds light SW-W

Avalanche Summary

Numerous natural (to size 2.5) and skier controlled avalanches (to size 2) were reported on Saturday. Most of these released on the recently buried snow surface, but some may have stepped down to the mid February layer. There was also a report of several remotely triggered avalanches. No new avalanches were reported on Sunday but widespread whumpfing was reported suggesting that prime conditions for triggering avalanches still exists. Snowpack test results are also showing the potential for human-triggered avalanches which have the potential for good propagation.

Snowpack Summary

Around 20-50 cm of dense storm snow now sits on a layer of surface hoar and/or a thick layer of facetted 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. The early February weak layer of facets, crusts, and surface hoar is buried down about 70-120 cm. There is no new info on this weak layer, but I suspect it remains active in many areas. Basal facets and depth hoar remain a concern in areas with thin or variable snow cover.

Problems

Storm Slabs

Up to 50 cm of dense storm snow overlies the previous snow surface of weak sugary facets, old wind slabs, or a melt-freeze crust. Triggering is more likely on steep unsupported or convex shaped slopes and in wind loaded areas on N to E 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

Possible - Likely

Expected Size

2 - 4

Persistent Slabs

A weak layer buried in mid-February is now down 60-120 cm deep. Triggering an avalanche on this layer would result in a very large and destructive avalanche.

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

2 - 5

Valid until: Mar 11th, 2014 2:00PM