Strong southerly winds are redistributing available snow into fresh pockets of wind slabs in the alpine and at treeline. Wind slabs are most reactive during their formation so use extra caution around freshly wind-loaded features.
Strong southerly winds are forming new wind slabs on lee slopes in the alpine and at treeline. New wind slabs overlie variable surfaces including old wind slabs and a crust of varying thicknesses. These slabs may be more reactive where they overlie the hard crust layer. Investigate the bond at this interface before committing to steep terrain.
On Wednesday, isolated pockets of small wind slabs were reported to be reactive to skier traffic in lees up to size 1. Riders should continue to be cautious around wind slabs at treeline and alpine elevations especially as snow accumulates Friday afternoon.
If you head to the backcountry please post your reports and photos to the Mountain Information Network, the information is very helpful to forecasters.
5 to 15 cm of soft snow is being redistributed by strong southerly winds into thin wind slabs in exposed areas. Fresh wind slabs overlie variable surfaces including old wind slabs and a crust of varying thicknesses. This crust is thick and supportive below treeline and on steep solar aspects and thin and breakable at treeline and above.
A crust from mid-January can be found down 40 to 70 cm deep. A number of weak layers exist within the middle and lower snowpack, but the thick crusts sitting above them make triggering avalanches on these layers unlikely. The areas of concern in terms of triggering a deeper layer are shallow rocky areas.
Thursday night
Cloudy with isolated flurries, 2-5 cm accumulation. Southerly ridgetop winds 30 to 50 km/h. Treeline temperatures -3 ˚C. Freezing levels 1200 m.
Friday
Mainly cloudy with flurries starting around noon, 5-15 cm accumulation. Southerly ridgetop winds 40 to 60 km/h. Treeline temperatures -1 ˚C. Freezing levels 1500 m.
Overnight storm increases in intensity. 25 to 40 cm of snow is expected overnight. 40 to 70 km/h south wind. Freezing levels fall to 1000 m.
SaturdayCloudy skies and scattered flurries, 5-15 cm accumulation. 20 to 40 km/h southerley ridgetop wind, treeline temperatures warm to -2 ˚C. Freezing levels 1400 m.
SundayCloudy with isolated flurries, 2-5 cm accumulation. 20 km/h westerly ridgetop wind, treeline temperatures warm to -2 ˚C. Freezing levels 1400 m.
More details can be found in the Mountain Weather Forecast.
