Avalanche Forecast

Issued: Mar 21st, 2013 9:55AM

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

Avalanche Canada triley, Avalanche Canada

Periods of strong solar radiation may weaken and release storm slabs on Southerly aspects where a buried crust may act as a good sliding surface. Cornices may also fall off due to solar warming.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Friday

Weather Forecast

Overnight and Friday: Unsettled convective weather is forecast to bring a few more cms of snow overnight and during the day. Amounts may be slightly enhanced in some of the up-slope areas. Alpine temperatures should drop to -14.0 overnight and the freezing level is expected to rise to about 900 metres during the day. Moderate West winds should become light Northerly with moderate gusts. Saturday: A ridge of High pressure is slowly moving into the interior regions from the coast. Cloudy conditions in the morning should clear gradually during the day. There is a chance of a few flurries in the morning. Freezing levels are expected to rise to 1000 metres under clearing skies. Sunday: The ridge of High pressure is expected to continue to bring mostly clear skies and light Northerly winds to the interior ranges. Overnight alpine temperatures are forecast to be about -13.0 with the freezing level rising to 900 metres during the day. Periods of strong solar radiation are expected.

Avalanche Summary

No new reports of avalanches. Poor visibility and travel conditions limited observations.

Snowpack Summary

There is close to a metre of storm snow that has fallen in the last few days. This storm slab is sitting above variable surfaces that include crusts and moist layers that were deposited during the wet (Pineapple Express) storm last week. Periods of strong winds in the alpine transported the storm snow into thick pockets of wind slab that may take several days to settle and bond to the old surface. Cornice growth has been reported to be extensive and weakly bonded. Natural cornice falls are a concern, especially if we see periods of strong solar radiation. Cornice falls or storm slabs in motion may step down to the weak layer of buried surface hoar from March 10th.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm slabs and pockets of wind transported snow may take a few days to settle and bond. Periods of strong solar radiation may trigger the storm slab where it is sitting on a buried crust.
The new snow will require several days to settle and stabilize.>Be cautious as you transition into wind affected terrain.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
The new load of storm snow may trigger the buried weak layer of surface hoar from March 10th that is now down about 100 cms. Large loads like cornice fall are expected to continue to trigger this layer.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Mar 22nd, 2013 2:00PM

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