Avalanche Forecast

Issued: Mar 12th, 2016 8:20AM

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

ghelgeson, Avalanche Canada

South Rockies.

Continued unsettled weather is expected to keep avalanche danger elevated, especially at higher elevations in wind exposed terrain.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Sunday

Weather Forecast

A cool unstable airmass moves into the region Saturday evening, which should deliver 1 to 8 cm of snow by daybreak Sunday. Sunday offers a brief break in the action before a second pulse arrives Sunday night. SUNDAY: Freezing Level starting around valley bottom, rising to 1500 m, 0 to 2 cm of snow during the day, moderate southwest winds. SUNDAY NIGHT: Freezing level holding at 1500 m, 2 to 15 cm of snow, moderate to strong southwest winds. MONDAY: Freezing level around 1500 m, trace of snow, moderate to strong southwest winds. TUESDAY: Freezing level starting around valley bottom, rising to 1500 m, no significant snow accumulations expected, light west / northwest winds.

Avalanche Summary

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. Natural cornice failures were also reported Friday to size 1.5. Reports from Thursday are limited but include skier-controlled size 1 wind slab avalanches. Natural wind and storm slab avalanche activity was expected on Thursday in response to heavy loading from snow, wind and rain.

Snowpack Summary

Approximately 25 cm of fresh snow is bonding poorly to a widespread supportive crust, with the most recent snow-line reaching 1800m in the Elk Valley. In exposed terrain, widespread very touchy wind slabs lurk below ridge-crests, behind terrain breaks and in chutes. Deeper in the snowpack, recent tests gave very easy sudden collapse results down 80cm on a southeast aspect at 1850m 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

Storm Slabs

Recent storm snow is bonding poorly to a buried crust and may be particularly deep and touchy on wind-loaded slopes.

Minimize exposure to sun exposed slopes when the solar radiation is strong.>Be cautious as you transition into wind affected terrain.>The new snow will require several days to settle and stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Continued warm temperatures and wind-loading will keep large droopy cornices weak. Not only are massive cornice falls a hazard in themselves, but they can also act a heavy trigger for slab avalanches on the slope below.

Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Mar 13th, 2016 3:00PM