Observations of persistent slab avalanches indicate buried weak layers are touchy, most recently below 1800 m. In the alpine, expect wind slabs on a variety of aspects.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
TONIGHT: Cloudy with flurries 3-5 cm, light to moderate north east winds, alpine temperature -17 C.THURSDAY: Cloudy with sunny breaks, winds switching from north east to southwest mid-day, alpine temperatures -11 C.FRIDAY: Cloudy with light precipitation, accumulation 5 cm, moderate south west winds, alpine temperature -8 C.SATURDAY: Cloudy with light precipitation, winds out of the east, alpine temperatures -8 C.
Avalanche Summary
Skier triggered small to large (size 1-2) wind slabs have been reported on various aspects in open areas over the past few days. Most recently a skier remote triggered a large wind slab at treeline on a south west aspect on Tuesday. On Tuesday, whumpfing in previously un-compacted (not tracked up when the weak layers formed) terrain was reported. Whumpfing in the sound a weak layer makes when it collapses from the weight of a slab above it in mellow terrain. If it were in steeper terrain, it would likely cause an avalanche. On the long weekend, many persistent slab avalanches were observed. A skier triggered a large (size 2 to 2.5) avalanche within a slide path near Fernie. The avalanche was about 40 to 80 cm deep, on a northeast aspect, and at 1700 m. The South Rockies Field Team attended the site on Tuesday and confirmed that the avalanche failed on a layer of surface hoar,
check out their report here. Also on Sunday a group of skiers
remote triggered a size 2 avalanche (no involvement) over a convexity in the Little Sand area at 1650 m. Cutblock type terrain in the Rolling Hills has also been the source of persistent slab observations
check the report out here .
Snowpack Summary
Storm snow from last week has been redistributed by wind, forming wind slabs in open areas at higher elevations. The wind was first westerly and switched to northeast, so wind slabs may be found on all aspects. In sheltered areas between 1600 and 1800 m, 20 cm of recent snow may sit on a weak layer of surface hoar crystals buried around Valentines Day in some locations.Two more persistent weak layers may be found within the snowpack. Surface hoar that was buried early-February may be found about 30 to 50 cm deep in shaded and sheltered areas above 1600 m. The mid-January layer of surface hoar is buried around 70 to 100 cm and is most prominent between 1600 m and 1900 m.
jcoulter,
Avalanche Canada
