Avalanche Forecast

Issued: Feb 18th, 2013 9:41AM

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

Avalanche Canada triley, Avalanche Canada

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

There was a lot of avalanche activity reported from Sunday. Skier controlled, skier accidental, and natural avalanches up to size 2.5 on various aspects and elevations. All of the avalanche activity reported released on the weak February 12th buried surface hoar layer.

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 20-50 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

An icon showing Storm Slabs
New snow has added to the load of the recent storm snow. This storm slab is expected to continue to be reactive above a weak layer of surface hoar and sun crusts.
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

Likely

Expected Size

1 - 5

Wind Slabs

An icon showing Wind Slabs
New wind slabs have developed at higher elevations. Older wind slabs may be buried by the new snow and may be difficult to locate.
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

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
There are older layers of buried surface hoar and crusts that are unlikely to be triggered by the weight of a skier or sledder, but may be triggered by large additional loads like cornice fall or wind/storm slab avalanches in motion.
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

Expected Size

2 - 6

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