Avalanche Forecast

Issued: Feb 8th, 2015 9:00AM

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

jlammers, Avalanche Canada

South Rockies.

The snowpack will need time to adjust to the heavy load of the new snow and rain saturation at lower elevations. Large avalanches are still a concern. Conservative terrain selection remains critical.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

The pineapple express will bring continued precipitation until Monday. On Tuesday and Wednesday a warm dry ridge of high pressure will develop. Monday: Up to 15cm of snow at higher elevations / Strong southwest winds / Freezing level at 1800m Tuesday: Trace amounts of snow in the morning - Mix of sun and cloud later in the day / Moderate northwest winds / Freezing level at 1500m Wednesday: Mix of sun and cloud / Light West winds / Freezing level at 1500m

Avalanche Summary

Several storm slab avalanches to size 2.5 were reported in the south of the region on Friday. On Saturday, storm slab avalanches to size 2 were also noted. I get the feeling this was just the tip of the iceberg as observations were extremely limited. Triggering storm slabs will remain a concern at higher elevations for the next few days. At lower elevations where precipitation has fallen as rain, I would expect ongoing loose wet and wet slab avalanche activity.

Snowpack Summary

In the alpine, up to 50cm of moist, dense snow overlies a touchy crust/surface hoar layer which was formed in late January. These new snow accumulations have been pushed by strong southwest winds into much deeper deposits in upper elevation lee terrain. At lower elevations very heavy rain has saturated the snowpack. I'm sure cornices are large and fragile.The sustained rain should continue to break down the late January crust, increasing the possibility of avalanches stepping down to deeper weak layers. The mid-December crust/facet/surface hoar combo is found down 50 - 95 cm. Rain and/or heavy storm loading could spark renewed activity at this interface with the potential for very large avalanches.

Problems

Storm Slabs

Deep, dense and destructive storm slabs have formed at upper elevations. Human triggering will remain a concern, especially due to a recently buried crust/ surface hoar layer.

Be cautious as you transition into wind affected terrain.>The new snow will require several days to settle and stabilize.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

Heavy rain and forecast warm temperatures will promote ongoing loose wet and wet slab avalanche activity. Wet avalanches can be pushy and entrain mass quickly. Use extra caution in steep lower elevation terrain.

Be cautious of wet sluffing in steep terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

The snowpack is rain-soaked and weak. This increases the likelihood of avalanches failing on deeply buried persistent weak crystals which formed in December. Although less likely, avalanches at this interface would be destructive in nature.

Be aware of the potential for very large, deep avalanches due to the presence of buried surface hoar or a facet/crust layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 9th, 2015 2:00PM