Reactive storm slabs are expected and have the potential to step-down to persistent layers.
Start with conservative terrain and gather information before committing to larger slopes.
A weak layer from early March is 100 to 150 cm deep, and the Jan & Feb layers are buried 200 to 300 cm. These remain a concern, especially in northerly alpine terrain. These layers have caused recent very large avalanches in the region.
Up to 25 cm of new snow may fall by late Saturday morning. Expect deeper and more reactive slabs on north and east-facing slopes due to wind.
Loose wet avalanches are possible at lower elevations or where the snow surface is moist/wet.
On Thursday, a few natural and human-triggered size 1-2 storm slabs and wet loose avalanches were observed.
Numerous, widespread and very large, naturally triggered avalanches (up to size 4) were reported in the region on Wednesday and Tuesday. Many slabs failed on or stepped down to persistent weak layers.
With further snow and wind in the forecast, storm slabs and persistent slabs are expected to be reactive to human triggers on Saturday.
Recent rain and warming created a moist/wet upper snowpack up to 70 cm deep, and capped by a crust. 10 to 20 cm of snow may now cover this crust, with an additional 10 to 25 cm forecast to fall overnight and through Saturday. Lower elevations may see rain and moist or wet surface snow. The new snow accompanied by strong southerly wind is expected to build storm slabs at upper elevations. Expect deeper and more reactive deposits on northerly slopes.
Persistent weak layers from January, February and March can be found 100 to 160 cm and 200 to 300 cm deep. These layers were very reactive in the recent warming event. Below this, the snowpack is well-settled and strong.
Friday Night
Cloudy with 10 to 20 cm of snow above 1000 m, possible rain below. 35 to 40 km/h south ridgetop winds. Treeline temperature -3 °C. Freezing level around 1300 m.
Saturday
Cloudy, with 0 to 5 cm of snow above 1000 m, possible rain below. 20 to 40 km/h south ridgetop winds. Treeline temperature -2 °C. Freezing level around 1300 m.
Sunday
Sunny. 30 to 40 km/h southeast ridgetop winds. Treeline temperature +2 °C. Freezing level rising to 1900 m.
Monday
Cloudy, with 5 to 15 cm of snow above 1200 m, possible rain below. 30 km/h variable ridgetop winds. Treeline temperature -2 °C. Freezing level rising to 1400 m.
More details can be found in the Mountain Weather Forecast.
