Avalanche Forecast

Issued: Apr 1st, 2015 8:52AM

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

ccampbell, Avalanche Canada

Sea To Sky.

Deep persistent weaknesses are still reactive in snowpack tests. Very large avalanches are still possible.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain on Friday

Weather Forecast

Unsettled weather is expected to bring a mix of sun and cloud with isolated flurries on Thursday, before a more organized system brings 5-15 cm of snow on Friday and another 5 cm on Saturday. Daytime high freezing levels are expected to hover around 1300 m for the forecast period and winds are expected to pick up to moderate southwesterlies on Friday.

Avalanche Summary

Over the past few days, explosives testing produced storm and wind slab avalanches and cornice releases to size 2.5. Since the Size 2.5 persistent slab avalanche on Cowboy Ridge in the Fitzsimmons Range on the weekend, we have not received any new reports of persistent avalanche avalanche activity, suggesting that these high consequence avalanches are becoming more stubborn.

Snowpack Summary

Another 5-20 cm of low density storm snow adds to the 40 cm of recent moist snow capped by a thin crust, that overlies a rain crust buried last Saturday. Reports suggest this crust exists up to at least 2200m. Strong southwest winds have shifted these new accumulations into touchy wind slabs in exposed terrain. A facet/crust persistent weakness buried mid-March is down approximately 70-130 cm and is still producing hard but sudden results in snowpack tests. This remains the chief concern amongst avalanche professionals in the region due to it's potential for very large avalanches.

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.

Choose well supported terrain without convexities.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Be aware of the potential for large, deep avalanches due to the presence of a buried crust/facet layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Storm Slabs

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

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 2nd, 2015 2:00PM