Wind slabs may be touchy and a warming trend has the potential of waking up buried weak layers. Travel conservatively during this period of uncertainty.
Strong southwest wind is forecast along with an increase in air temperature. Wind slabs may be touchy in lee terrain features, particularly near ridges.
A layer of surface hoar is buried 30 to 100 cm deep. There is uncertainty on whether the layer will reawaken during the air temperature rise. Use added caution during periods of warming, particularly in clearings around treeline.
Triggering large, deep persistent slab avalanches is a low likelihood but high consequence problem that is most likely in shallow, rocky start zones. The likelihood of triggering deeper weak layers may increase as the air temperature rises on Monday.
SUNDAY NIGHT: Clearing through the night, moderate southwest wind, alpine temperature -5 C, freezing level rising to 700 m.
MONDAY: Mix of sun and cloud, moderate to strong southwest wind, alpine temperature -3 C, freezing level 1200 m.
TUESDAY: Cloudy with snowfall, accumulation 5 cm, light to moderate southwest wind, alpine temperature -6 C, freezing level 800 m.
WEDNESDAY: Morning snowfall then a mix of sun and cloud, accumulation 2 to 5 cm, light west wind, alpine temperature -8 C, freezing level 800 m.
Numerous large (size 2) wind slabs were triggered by humans and explosives on Saturday. They were generally 10 to 40 cm deep and occurred at treeline and alpine elevations.
A couple deep persistent slabs were triggered by explosives. They were large (size 2) and occurred in the alpine, scrubbing to the ground.
Around 15 cm of recent snow and strong southwest wind has produced wind slabs in lee terrain features, particularly near ridges.
A layer of surface hoar that formed in late December appears to be less reactive than it was a week ago and can be found 70 cm deep around Golden, 30 cm deep around Invermere, 70 cm deep around Kimberley, and 100 cm deep along Kootenay Lake. As usual for the Purcells, the base of the snowpack contains basal facets and it remains possible to trigger these deep weak layers in shallow rocky start zones or from a heavy trigger such as a cornice fall or explosives. The likelihood of triggering buried weak layers may increase as the air temperature rises on Monday.
