Avalanche Forecast

Issued: Mar 13th, 2016 9:05AM

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

Avalanche Canada ghelgeson, Avalanche Canada

A shot of fresh snow and wind Sunday night will keep the danger elevated Monday. Give corniced slopes a miss as temperatures begin to warm Monday afternoon.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

The South Rockies will see a relatively modest shot of snow and wind Sunday night before the atmosphere begins to shift to a more classical spring pattern. This should result in a strong diurnal temperature swing with very little in the way of precipitation expected for the forecast period. SUNDAY NIGHT: Freezing level around 1800 m at sunset, steadily lowering to valley bottom overnight, 2 to 10 cm of snow, moderate to strong southwest winds. MONDAY: Freezing level starting at valley bottom rising to 1400 m, 1 to 4 cm of snow, moderate west / southwest winds. TUESDAY: Freezing level starting at valley bottom, rising to 1600 m, no significant precipitation expected, moderate west / northwest winds. WEDNESDAY: Freezing level starting near valley bottom, rising to 1600 m, no significant precipitation, light west / northwest winds.

Avalanche Summary

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. 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 unlikely to be bonding well to a widespread supportive crust, with the most recent snow-line reaching 1800 m in the Elk Valley. In exposed terrain, widespread and potentially touchy wind slabs likely lurk below ridge-crests, behind terrain breaks and in chutes. 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

Storm Slabs

An icon showing Storm Slabs
Recent storm snow may be bonding poorly to a buried crust.  Storm slabs are expected to be most problematic on wind loaded slopes at upper elevations.
Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

An icon showing Cornices
Continued mild day time temperatures and continued winds 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 14th, 2016 2:00PM

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