Avalanche Forecast

Issued: Apr 13th, 2013 10:19AM

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

jlammers, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Sunday: Very light snowfall / Light northeast winds / Freezing level at 1400mMonday: Mix of sun and clouds / Light east winds / Freezing level at 1400mTuesday: Mix of sun and cloud / Calm winds / Freezing level at 1600m

Avalanche Summary

Observations are becoming more limited; however a size 2 natural wind slab avalanche was observed on a lee alpine feature on Friday. A size 2 slab was also ski cut on a steep southeast facing convex roll. Surface hoar was the suspected interface.I would expect ongoing storm instabilities in the wake of new snow and wind on Friday night.

Snowpack Summary

Moderate to locally heavy snowfall on Friday night has created touchy new storm/wind slabs, especially near ridge top. This will add to existing storm slab and wind slab problems at alpine and treeline elevations. A surface hoar interface is buried within the upper metre or so of the snowpack, mainly on high-elevation northerly aspects. It may be slowly gaining some strength, but these slopes should still be treated with suspicion. On other slopes, recent storm snow overlies a crust, with a variable bond. At low elevations, moderate accumulations overlie previously rain-soaked snow which is now refrozen and strong.Recent wind and snow has added to the size and fragility of large cornices.

Problems

Storm Slabs

Snowfall on Friday night and variable winds have created new storm slabs, especially near ridge top and on slopes in the lee of the wind.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Avoid travelling in areas that have been reverse loaded by winds.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

A layer of surface hoar is buried about a metre down, mainly on high northerly aspects. A surface avalanche stepping down, cornice fall, or the weight of a person from a thin-spot trigger point could trigger it.

Conditions have improved, but be mindful that deep instabilities are still present.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 6

Valid until: Apr 14th, 2013 2:00PM