Avalanche Forecast

Issued: Mar 15th, 2013 11:05AM

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 pgoddard, Avalanche Canada

Danger ratings for Saturday are uncertain and will hinge on the amount of refreezing that occurs overnight. If you're traveling on a thickly refrozen snow surface, chances are that avalanche danger's not too bad.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Saturday: Light snow, starting late in the day. Moderate to strong W winds. Alpine temperature near -4.Sunday: Light to moderate snow. Moderate to strong NW winds. Alpine temperature near -5.Monday: Light snow. Light SW winds. Alpine temperature near -9.

Avalanche Summary

A widespread avalanche cycle was observed during the storm, which was particularly active as temperatures warmed up. Most avalanches were in the size 1-2 range and failed within, or at the base of, the storm snow. They were observed on all aspects and at most elevations.

Snowpack Summary

The recent storm dropped about 15-40 cm snow at upper elevations, while rain soaked the snowpack below about 2000 m. Moist or wet snow at the surface overlies less dense snow, creating “upside-down” storm snow. Strong NW through SW winds may have redistributed snow into wind slabs and created cornices at alpine elevations. Below the storm snow is a layer of buried surface hoar and/or a crust, which increased the reactivity of storm slabs. Deeper in the snowpack, a weak interface buried in mid-February is still on the radar. Although unlikely to be triggered, it remains possible with a very heavy load or from a thin-spot trigger point, particularly at high alpine elevations where the snowpack above this layer is free of supportive crusts.As temperatures cool, wet slab/loose wet avalanche problems should improve, but persistent slab concerns will linger at upper elevations, especially on slopes which didn’t avalanche during the storm.

Problems

Storm Slabs

An icon showing Storm Slabs
Recent storm snow may take some time to stabilize, especially if temperatures remain mild.
Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Start by testing the bond of storm snow on low angled slopes before considering steeper objectives.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
A weak interface buried in the upper snowpack could still be triggered with a heavy load, like cornice fall, or from a thin-spot trigger point.
Be aware of thin areas that may propagate to deeper instabilites.>Avoid steep slopes below cornices.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 7

Valid until: Mar 16th, 2013 2:00PM