Avalanche Forecast

Issued: Mar 7th, 2014 8:36AM

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

esharp, Avalanche Canada

Sea To Sky.

Freezing levels may rise higher than forecast. Where rain falls it will saturate the upper snowpack and cause loose wet and wet slab avalanches.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Synopsis: A series of fronts is sliding down the BC coast. The warm front should pass over the Sea to Sky region on Saturday, followed by the cold front Sunday morning. Expect 30 to 60mm of precipitation before conditions dry out briefly on Monday.Tonight and Saturday: Heavy snow / Moderate to strong SW winds / Freezing levels 1500-1700mSunday: Heavy snow / Moderate to strong SW winds / Freezing levels 1500-1700mMonday: Flurries / Light W winds / Freezing levels 1300m.Note: Weather models have been typically under predicting freezing levels thus far through this system.

Avalanche Summary

A cycle of small natural and explosive controlled storm snow avalanche occurred Thursday in response to heavy loading and mild temperatures. Natural activity should taper off a bit on Friday as conditions dry out briefly.Cornices are finally beginning to mature and should be given a wide berth.

Snowpack Summary

Between 30 and 60cm of rapidly settling new snow fell in the recent storm. This was accompanied by strong S-SW winds that formed a thick wind slabs in open lee terrain. The early March melt-freeze crust can now be found down 60-120 cm. This layer was found on all aspects at treeline and below, and on all but North aspects in the alpine. Recent snowpack tests give easy to moderate popping shears on this layer, and show potential for wide propagation.The mid February crust/facet combo appears to be rounding and bonding in areas where it is buried 150 cm or deeper. In shallow snowpack areas, where the weak layer is buried less than 100 cm deep, it continues continue to fail with popping shears in snow profile tests. Big un-supported alpine North aspects are the most likely place to find (and potentially trigger) this well preserved weak layer.Given the current layering in the snowpack be aware of the potential for smaller avalanches to step down and trigger deeper layers and produce very large avalanches.

Problems

Storm Slabs

Forecast heavy precipitation will continue to to load the melt-freeze crust buried in early March.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Persistent Slabs

Heavy loading could be enough to trigger the mid-February facet/crust combo, particularly on northerly aspects. Step down avalanche are possible.

Be aware of the potential for large, deep avalanches.>Avoid lingering in runout zones.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 8th, 2014 2:00PM