New slabs may form overnight and through the day. Heading out with a conservative mindset will promote a safe day.
New storm slabs may form in sheltered areas and wind slabs in wind-exposed terrain. These slabs will continue to build over the 100+ cm of snow that fell since January 1, which may take some more time to bond to various weak or smooth layers.
WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 5 to 15 cm, 20 km/h southwest wind, alpine temperature -11 C.
THURSDAY: Cloudy with snowfall, accumulation 5 to 15 cm, 30 km/h southwest wind, alpine temperature -7 C.
FRIDAY: Cloudy with snowfall then clearing, accumulation 20 to 40 cm, 30 km/h southwest wind, alpine temperature -5 C.
SATURDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 20 km/h southwest wind, alpine temperature -11 C.
Many storm slab avalanches were triggered by explosives and riders on Tuesday and Wednesday. The avalanches were generally small to large (size 1 to 2) and at all elevation bands.
Looking forward to Thursday, new storm slabs may form at all elevations and on all aspects in sheltered terrain, and wind slabs in lee terrain features at higher elevations.
Anywhere from 10 to 30 cm of snow is forecast for Wednesday night into Thursday, which may form new storm slabs in areas sheltered from the wind and wind slabs in exposed terrain. This snow will build on the 100+ cm of snow that has fallen since January 1.
All of this snow overlies various old surfaces that formed during the cold spell in late December. These layers include a melt-freeze crust on sun-exposed aspects, weak and feathery surface hoar in areas sheltered from the wind, weak and sugary faceted grains, and hardened surfaces from strong wind. There is uncertainty in how long it will take for all this snow to bond to these layers.
Around 150 to 250 cm deep, a weak layer of faceted grains may be found above a melt-freeze crust that formed in early December. The layer is most prominent between 1700 and 2100 m. The last observed avalanche on this layer was around December 24, suggesting that this layer has become dormant. The most likely place to trigger it would be in thin, rocky snowpack areas.
The lower snowpack is well-settled and strong.
