Avalanche Forecast

Issued: Mar 31st, 2015 9:09AM

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

jlammers, Avalanche Canada

South Coast.

The storm may have ended, but a persistent avalanche problem still exists. Large and destructive avalanches are still possible.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Expect a mix of sun and cloud on Wednesday and Thursday morning. By late Thursday and Friday, a more organized front will bring about 10cm of new snow. Ridgetop winds should remain generally light from the northwest on Wednesday and Thursday, becoming strong from the southwest with Friday's system. Daytime freezing levels should hover around 1200m

Avalanche Summary

Over the past few days, several natural wind slab avalanches to size 2 were observed in the north of the region. In many cases, these wind slabs were triggered by cornice falls. We have not yet heard how persistent avalanche activity panned out in response to the recent storms. My best guess is that we may be transitioning into a lower probability-high consequence avalanche pattern with this persistent weak layer.

Snowpack Summary

Up to 30cm of recent snowfall overlies a rain crust that was buried on March 28th. Reports suggest this crust exists up to about 2100m. Strong southwest winds have shifted these new accumulations into wind slabs in exposed high elevation terrain, while rain has saturated the snowpack below about 1600m. The most critical snowpack layer in the region is a facet/crust interface which lies anywhere from 50-100 cm below the surface. This persistent weak layer (which is most prominent in the north of the region) was responsible for several naturally triggered avalanches to size 3 over the past week, and continues to produce sudden snowpack test results. Although the likelihood of triggering this layer has decreased somewhat, avalanches failing at this layer may not be survivable. At lower elevations, rain has saturated the snowpack. Layers below the critical mid-March interface are generally considered to be well-settled and strong.

Problems

Persistent Slabs

There's some uncertainty as to how the deeply buried weak layers have responded to recent storms. A cautious approach is still required as avalanches failing at this interface may not be survivable. Conservative terrain selection is still critical.

Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Wind Slabs

Recent storm accumulations have been shifted into deeper deposits by strong southwest winds. Watch for increased reactivity in high elevation lee terrain.

Be alert to conditions that change with elevation.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 1st, 2015 2:00PM