Watch for pockets of stiff wind slab at upper elevations from recent northerly outflow winds. These slabs may be in atypical areas due to reverse-loading and could be particularly reactive where they overlie a slick crust.
Northerly outflow winds may have created stiff wind slabs at upper elevations where dry surface snow exists. Watch for wind-loaded pockets, especially just below ridgetops and in extreme and very steep terrain. Wind slabs may be reactive to human triggering where they overlie a slick crust.
Sun and warm temperatures arrived last Wednesday and several natural wet loose avalanches were reported to size 1.5 on steep solar aspects.
On Friday, thin but reactive size 1 wind slabs were skier-triggered in steep alpine ridgetop features.
Looking forward to Sunday, riders should be cautious around pockets of stiff wind slab at upper elevations. These slabs may fail easily where they overlie a slick crust and will be in more atypical locations, as northerly winds have created a reverse-loading pattern.
Please continue to share any observations or photos on the Mountain Information Network.
A melt-freeze crust covers 20-40 cm of settling snow on solar slopes in the alpine. On sheltered polar slopes in the alpine, a crust has formed and should break down once the incoming cold weather gets a chance to work on it. Both of these crusts can be found from 2200 m to 1000 m in elevation.
A thick crust from mid-January can be found down 40-70 cm deep. A number of weak layers exist within the mid 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.
Saturday night
Clear. Alpine temperatures reach a low of -15 °C. Ridge wind 20 km/h gusting to 50 km/h from the north. Freezing level at valley bottom.
Sunday
Sunny. Alpine temperatures reach a high of -7 °C. Mostly light ridge wind occasionally gusting to 35 km/h from the north. Freezing level at valley bottom.
Monday
A mix of sun and cloud with an alpine temperature inversion. Alpine temperatures reach a high of -7 °C. Mostly light ridge wind occasionally gusting to 40 km/h from the west. Freezing level at valley bottom.
Tuesday
Cloudy with sunny periods. Alpine temperatures reach a high of -9 °C. Mostly light ridge wind occasionally gusting to 30 km/h from the west. Freezing level at valley bottom.
More details can be found in the Mountain Weather Forecast.
