Avalanche Forecast

Issued: Feb 18th, 2013 9:35AM

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

triley, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Due to variable snowpack conditions for the entire period

Weather Forecast

Overnight and Tuesday: A weak upper trough is forecast to move across the region tonight bringing moderate Southwest winds. The trough should continue to influence the interior regions on Tuesday. Expect mostly cloudy conditions with light winds and very light precipitation. Freezing levels are expected to rise to about 1000 metres during the day.Wednesday: The next weak ridge of high pressure should move into the interior ranges to fill in behind the trough as it exits into Alberta. Expect gradually clearing skies, light winds and freezing levels near the valley bottoms. There is a chance of some strong solar radiation in the afternoon.Thursday: Another trough is expected to drift into the interior from the coast. Snow fall amounts are un-certain at this time.

Avalanche Summary

Numerous natural avalanches were reported from various aspects and elevations up to size 2.0 that were releasing in the storm snow. Skiers controlled avalanches up to size 1.5 in the storm snow. There was one report of a skier accidental avalanche that released from a steep convex roll in the storm snow and was about size 2.0, depositing debris into a terrain trap that piled up to 3.0 metres.

Snowpack Summary

New snow has added to the recent storm slab above the February 12th weak surface hoar layer. This layer is now buried down about 30-60 cms depending on where you are in the region. This variable storm slab is also above a sun crust on Southerly aspects. New wind slabs developed at higher elevations due to the new snow and wind during the storm. These soft new wind slabs may be hiding stiffer wind slabs that are a couple of days older. Deeper persistent weak layers from early February and late January continue to show planar failures when moderate to hard forces are applied to snow profile tests. These deeper layers have not been reactive to the loads associated with recreationalists, but they may be triggered by large loads like an avalanche in motion, or a cornice fall.

Problems

Storm Slabs

The storm slab is expected to continue to be sensitive to skiers and sledders. This weak layer may linger for a while. Solar warming may cause the storm slab to be very sensitive.

The new snow will require several days to settle and stabilize.>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

Wind Slabs

New wind slabs may take a couple of days to settle and bond.

Be cautious as you transition into wind affected terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

There are older layers of buried surface hoar and crusts that are buried down about 80-110 cms. These layers continue to show results in snow profile tests and may be triggered by large additional loads.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Feb 19th, 2013 2:00PM