South Rockies

Windslabs & buried weak layers mean that we need to keep playing it cautious a bit longer in wind affected alpine terrain & exposed treeline features. Remember that a small windslab can trigger a deeper layer in a step-down. Enjoy your holiday riding & avoid the steep alpine.

A building high pressure system will bring a mix of sun and clouds, cool temperatures and light to moderate winds.  

Saturday night: Clear with cloudy periods. Alpine low temperatures near -7C and freezing levels valley bottom. Ridgetop wind light gusting moderate from the west.

Sunday: Mix of sun and cloud. Alpine high temperatures near -7C and freezing levels valley bottom. Ridgetop wind light gusting moderate from the west/southwest.

Monday: Mix of sun and cloud. Alpine high temperatures near -9C and freezing levels valley bottom. Ridgtop winds light and variable. A mild temperature inversion may bring valley clouds and warmer clear temperatures above.

Tuesday: A mix of sun and clouds. Alpine low temperatures near -14C and freezing levels dropping to valley bottom. Ridgetop wind moderate gusting strong from the southwest.

No new avalanches were reported within the forecast region. However, every region surrounding the south rockies reports a similar story: wind slabs are reactive (most are size 1 but a few size 2) and sometimes step-down to trigger deeper layers (size 2-3). Wind slabs are reactive on fans, cross-loaded features and in reverse loaded terrain. Sluffing of loose dry snow is building mass to size 1 from steep wind sheltered terrain. A nearby neighbour reported a large avalanche (size 2) that initated as a windslab or cornice failure and stepped down to the December crust on Friday. Another neighbour reported a large (size 2) windslab from a west aspect from cross-loading from recent variable east winds.  

On Thursday there were reports of small (size 1) and large (size 2) windslabs from explosive control within the region and explosive controlled very large (size 3) avalanches and cornice triggered very large (size 2.5-3) avalanches from adjacent regions. The previous day, numerous natural wind slab avalanches up to size 2 were reported on Wednesday from our field team in the Crowsnest. These were mostly seen from West aspects in the alpine. On Tuesday widespread natural avalanche activity up to size 3 was reported through the region. Many of these avalanches ran deep into their runout zones.

Please consider sharing your observations on the Mountain Information Network. Thank you to those that have already submitted this winter!

30-50 cm of recent storm snow blanketed the region by Tuesday morning from a series of recent storms. Recent strong to extreme winds have redistributed some of this new snow building wind slabs on leeward slopes and scouring windward slopes. Much of this wind was west / southwest but variable winds have been reported across the region - including northerly winds.

Below 1800m a rain crust has about 10-20cm of recent snow on top of it. Above this elevation, a deeper crust remains a concern. A deeper crust from early December is down 70-100 cm. This persistent weak layer, with facetted crystals and surface hoar crystals above and/or below it may be reaching a tipping point. Smaller avalanches may step-down to this weak layer. 

The base of the snowpack consists of a hard melt-freeze crust from early-November that may also have weak crystals around it. This potential avalanche problem is dormant at this time, however; it remains on our radar. The most likely spot to trigger it would be on thin and rocky slopes or, like above, from step down avalanches in the recent storm snow.

• Be alert to conditions that change with elevation and wind exposure.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Avoid exposure to slopes that have cornices overhead.