Avalanche Forecast

Issued: Mar 6th, 2016 7:57AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is low. Known problems include Wind Slabs and Cornices.

Avalanche Canada jlammers, Avalanche Canada

Watch for ongoing wind slab development throughout the forecast period.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

An active weather pattern will deliver continued precipitation to the region for the forecast period. Expect daily accumulations of 8-12cm with freezing levels hovering around 800m. Ridgetop winds will be strong to extreme from the southwest on Monday, decreasing to moderate from the south on Tuesday and Wednesday.

Avalanche Summary

Over the last few days several newly formed wind slab avalanches to size 1.5 were ski cut in steep, higher elevation terrain. On Saturday, a size 2 slab avalanche was accidentally triggered on Oscar Peak northwest of Rosswood. The avalanche occurred on a steep roll at about 1400m and is thought to have failed on recently buried surface hoar. With new snow and wind in the forecast, I would expect ongoing wind slab activity for the forecast period.

Snowpack Summary

Over the past few days daily snowfall accumulations have generally been in the 5-15cm range with the highest accumulations occurring in the south of the region. Strong to extreme ridgetop winds have shifted the new snow into new wind slabs at treeline and in the alpine adding to an ongoing wind slab problem. About 60cm below the surface you'll likely find a crust that was buried on February 28th. A report from northwest of Rosswood suggests a recently buried layer of surface hoar may also exist in the upper snowpack, although I'm unsure of its size or distribution. An older crust buried in early February can now be found around 80-120cm below the surface. This crust, which may coexist with small facets or decomposing surface hoar, was recently producing sudden planar results in tests. Although no recent avalanches were reported to have failed at this interface, I'd remain suspicious of this layer in steep, unsupported terrain at treeline and in the alpine.The mid pack is generally well settled and strong.

Problems

Wind Slabs

An icon showing Wind Slabs
Ongoing snowfall and extreme winds continue to create fresh wind slabs at treeline and in the alpine. Watch for triggering in the lee of ridgecrests and terrain breaks.
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: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

An icon showing Cornices
Cornices are reported to be very large and weak. Stay well back from ridgecrests, and watch your overhead hazard.
Extra caution needed around cornices with current conditions.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Mar 7th, 2016 2:00PM

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