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Avalanche Canada bcorrigan, Avalanche Canada

South Rockies Avalanche Forecast

Feb 23rd, 2016 7:41AM

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

Rising temperatures may push the hazard higher than forecast.  Use extreme caution traveling near, or under cornices

Summary

Confidence

Moderate - Freezing levels are uncertain on Thursday

Weather Forecast

A ridge of high pressure has established itself over BC and western Alberta bringing generally clear skies and warm daytime temperatures.  Freezing  levels should drop to valley bottom overnight and may rise as high as 3000 metres later in the week. Although there is some disagreement in forecast models, expect unusually high alpine temperatures for Thursday and Friday.

Avalanche Summary

Natural avalanche activity appears to have slowed down west of the divide but there have been reports of skier controlled wind slabs to size 1.  On the eastern slope, no new avalanches have been reported but potential wind slab activity is still on the radar.

Snowpack Summary

New snow with wind during the weekend contributed to wind slabs forming in lee terrain at treeline and in the alpine. A melt freeze crust which formed during the 2nd week of February has been reported between 40and 70 cm., perhaps more deeply buried in the south of the region. This crust layer has also been reported with surface hoar in some places, for the most part on high and north facing terrain.  This melt-freeze crust is  a critical layer to keep track of.  Rain and warm temperatures at lower elevations have created a 2 to 4cm rain crust, mostly on on south aspects below 1800 m.  West of the divide, a layer of buried surface hoar has been reported around 45cm below the surface. The last storm accompanied by mod SW winds has encouraged cornice growth. These cornices are reported to be huge and unsupported. With warm weather and sun in the afternoon, these could become a significant hazard.  New surface hoar growth is  now being reported throughout the region.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely

Expected Size

1 - 3
A wind slab avalanche could provide a big enough force to trigger deeply buried instabilities. Use caution moving into suspected wind loaded terrain
Assess start zones carefully and use safe travel techniques.>Be careful with wind loaded pockets on steep slopes below ridge crests.>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.

Cornices

An icon showing Cornices

Likelihood

Possible

Expected Size

2 - 4
Cornices are growing large and fragile.  Use great care traveling under or near them.
Extra caution needed around cornices with current conditions.>Give cornices a wide berth when travelling on or below ridges.>Cornices become weak with daytime heating. >

Aspects:

North, North East, East, South East.

Elevations:

Alpine, Treeline.

Valid until: Feb 24th, 2016 2:00PM