Avalanche Forecast

Issued: Dec 27th, 2015 11:24AM

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

Avalanche Canada ghelgeson, Avalanche Canada

Strong winds over the weekend have formed wind slabs up to 40cm in depth in wind exposed terrain. Plan your day so that you avoid freshly wind loaded features.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

Dribs and drabs of isolated flurries are expected in the South Rockies for the next few days. High pressure sneaking up from Idaho should be firmly established by Wednesday evening resulting in clear skies, freezing levels at valley bottom and light variable winds. SUNDAY NIGHT: 1 to 5cm of snow. MONDAY: 2 to 5cm of snow, freezing level at valley bottom, light variable winds. TUESDAY: 1 to 2cm of snow, freezing level at valley bottom, light variable winds. WEDNESDAY: Skies should begin to clear in the afternoon, no precipitation expected, freezing level at valley bottom, light N/NW winds. For more detailed mountain weather information visit: avalanche.ca/weather

Avalanche Summary

On Saturday control work and natural failure resulted in wind slabs up to size 2 on NE facing terrain at 2100m. These fresh wind slabs were failing on the Boxing Day facets. On Friday numerous loose dry avalanches ran naturally to size 1 on east through southeast facing features around 2250m. On Thursday control work produced numerous small loose snow avalanches within the recent storm snow. On Wednesday we received a report of a skier triggered size 1 wind slab on a north aspect at 1800m. It's thought that this avalanche failed on the December 9th melt freeze crust which was down 40cm at the location of the avalanche.

Snowpack Summary

Up to 50cm of storm snow has fallen in the last week. It's been cold and this snow is still quite low density below treeline where it remains unconsolidated. At and above treeline winds from the north and now south/southwest have added a touch of cohesion which has formed fresh wind slabs up to 40cm in depth. These wind slabs rest on a layer of loose faceted snow that is up to 20cm thick. Strong SW winds over a week ago formed cornices that began failing on Boxing day (in the Lizard Range). The mid-December surface hoar may be present down around 50cm on north facing features below treeline. There may be a crust near the bottom of the snowpack from early December below 2100m.

Problems

Wind Slabs

An icon showing Wind Slabs
Strong winds over the weekend formed wind slabs up to 40cm in depth in wind exposed terrain.  These slabs will likely remain sensitive to rider triggering for at least the next few days.
A bit of snow Sunday night may hide fresh and still sensitive wind slabs that were formed over the weekend. Use ridges and ribs to avoid wind loaded features.>Many cornices are at or near their breaking point. Do not travel on or below these things at this time, you don't need a scary cornice story.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Dec 28th, 2015 2:00PM