Avalanche Forecast

Issued: Mar 14th, 2016 9:20AM

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

triley, Avalanche Canada

South Rockies.

Expect new wind slabs to develop with forecast winds and new snow available for transport. Minimise exposure to cornices at this time.

Summary

Confidence

Moderate - Wind speed and direction is uncertain on Tuesday

Weather Forecast

Moderate to strong westerly winds overnight with 2-3 cm of new snow and freezing levels down to valley bottoms. Some convective flurries expected during the day Tuesday with moderate westerly winds and freezing levels rising up to 1500 metres. A good freeze is expected on Wednesday morning before freezing levels climb up to 1500 metres during the day under mostly clear skies and light winds. Clouding over Wednesday night with 5-8 cm expected by Thursday morning with moderate northeast winds. A mix of sun and cloud on Thursday with light winds.

Avalanche Summary

On Monday our field team in the Crown Mtn area observed a natural cornice fall size 2.0 that did not release a slab on the steep slope below. The field team also observed the debris from a previous cornice fall that probably released over the weekend. On Saturday a few natural cornice failures to size 2 were observed in extreme terrain. On Friday a few different very large avalanches (to size 3.5) were observed that failed naturally on southerly facing alpine features. These avalanches were likely triggered by falling chunks of cornice impacting thin snowpack areas in the far north of the region. Debris ran down the track well into the below treeline vegetation band.

Snowpack Summary

At 1920 metres in the Crown Mtn area there was 17 cm of new snow above a breakable 2 cm crust. Below the crust there was moist snow at this elevation. We estimate the the crust extends up to about 2000 metres. Strong southwest winds have created widespread wind slabs at treeline and above. Deeper in the snowpack, recent tests gave very easy sudden collapse results down 80 cm on a southeast aspect at 1850 m on the deep persistent facet/crust weakness that was buried early December. Watch this weakness with extreme warming from sun-exposure, or warming/loading from rain. Cornices are also reported to be huge and weak. Check out the latest SoRo field team video on Instagram: @avcansouthrockies

Problems

Wind Slabs

Strong southwest winds and new snow have combined to develop new wind slabs at treeline and in the alpine. Wind slab avalanches may propagate wide fractures where they are sitting on a crust.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Cornices are large and fragile. Rapid new cornice growth may release naturally or be easily triggered by travelling near ridges.

Give cornices a wide berth when travelling on or below ridges.>Pay attention to overhead hazards like cornices.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Mar 15th, 2016 2:00PM