A nasty persistent slab has woken up and more snow is coming. The consequences of triggering an avalanche could be much higher than surface instabilities suggest.
Weak layers that formed during the January drought have become active with increased load and warm temperatures. Smaller storm slabs may step down to these layers and become large avalanches.
Additional snowfalls and high winds will create reactive storm slabs. Expect hazard to increase with elevation and to be greatest in leeward terrain. At higher elevations, these slabs have the potential to step down to deeper layers.
Evidence of wet natural avalanche cycles was observed after Sunday's storm. Several storm slabs (up to size 3) were released with numerous stepping down to the late-Jan/early Feb persistent layers around 60 to 80 cm deep in the snowpack. This problem remains a serious concern on steep northerly slopes at treeline and above as the next storm brings more snowfalls.
15 to 25 cm of new snow accumulated overnight Sunday along with strong to extreme winds, bringing storm totals to ~50 to 80 cm. These storm totals overlie problematic faceted snow, or surface hoar in sheltered terrain. In exposed terrain, a sun crust is present up to 1700 m while wind-affected surfaces exist at upper elevations.
A weak layer, buried at the end of January, is now 80 to 100 cm deep in the snowpack. This may present as a crust on sunny slopes, sugary facets in most places, and surface hoar in sheltered spots. The last storm woke this layer up decisively and both natural avalanches and human triggering on this layer are a serious concern.
Monday Night
Cloudy with 10 to 15 cm of new snow. 40 to 60 km/h southeast ridgetop wind. Treeline temperature stable around -4°C. Freezing level around 1200 m.
Tuesday
Cloudy with isolated flurries up to 5 cm of new snow. 10 to 20 km/h northwest ridgetop wind. Treeline temperature stable around -2°C. Freezing level around 1500 m.
Wednesday
Partly cloudy. 40 to 60 km/h southeast ridgetop wind. Treeline temperature stable around +4°C. Freezing level reaching to 2500 m.
Thursday
10 to 15 cm of new snow. 50 to 70 km/h southwesterly ridgetop wind. Treeline temperature 0°C. Freezing level lowering to 1200 m.
More details can be found in the Mountain Weather Forecast.
