Avoid avalanche terrain. Heavy snowfall, rain, and warm temperatures have resulted in very dangerous avalanche conditions.
New snow and warming will stress weak layers of surface hoar buried 50-120 cm deep. This could result in large avalanches that propagate across terrain features and run far distances.
Heavy accumulations of new snow and strong wind have created large unstable slabs at upper elevations.
Rain will destabilize the surface snow at lower elevations.
MONDAY NIGHT: Moderate rain up to 1200 m and 5-15 cm of snow above, moderate wind from the southwest, alpine temperatures around 0 C.
TUESDAY: Moderate rain up to 1200 m and 5-15 cm of snow above, light wind from the west with 40 km/h gusts, freezing level around 1500 m with alpine high temperatures around +1 C.
WEDNESDAY: Scattered flurries with another 10-30 cm of snow, moderate wind from the southwest, freezing level drops to 300 m and alpine high temperatures drop to -5 C.
THURSDAY: Isolated flurries with 5-10 cm of snow, light wind from the south, alpine high temperatures around -5 C.
Monday's storm likely caused natural avalanches and set Tuesday up for very dangerous avalanche conditions. The transition from snow to rain could cause a mix of avalanche problems including storm slabs, wind slabs, and wet loose avalanches. An additional concern is larger persistent slab avalanches on buried surface hoar layers. These weak layers produce large avalanches (size 3) on Saturday and will be under additional stress with the warm temperatures.
As of 4 pm on Monday afternoon about 30 cm of snow has fallen across southern parts of the region. As the storm continues into Monday night it is expected to get warmer, with rain reaching up to 1200 m. By Tuesday afternoon there could be another 10-30 cm of snow in the alpine while lower elevations get soaked by rain. This will result in a mix of surface conditions with storm slabs, wind slabs, and wet loose avalanches occurring at different elevations. In addition to problems with the new snow and rain, the warm temperatures will cause significant stress on the two layers of surface hoar buried 50-120 cm deep. Reports from the Shames area suggest buried surface hoar can be found on all aspects, but is more prevalent on southeast to southwest aspects around 800-1400 m. Overall the snowpack will be under stress from the new snow, rain, and warming on Tuesday. Things should improve as temperatures cool the following days.
