Heavy loading from new snow, wind, and rain will create very dangerous avalanche conditions. Avoid avalanche terrain and exposure to overhead hazard.
A weak layer of facets overlying a crust exists down 50 to 100 cm. Heavy loading from new snow, rain, and wind may cause this layer to become active, producing large and consequential avalanches.
Where the storm snow remains dry reactive storm slabs can be expected, particularly in wind-loaded terrain.
As snowfall transitions to rain and soaks the upper snowpack, expect wet loose avalanches to occur in steep terrain.
On Thursday, skiers triggered several storm slab avalanches (size 1-2) from alpine and treeline terrain near Mount Arrowsmith.
We suspect a natural avalanche cycle will occur on Thursday night and into Friday as freezing levels rise. Storm or persistent slab activity can be expected where the new snow remains dry. As snow transitions to rain, a widespread wet loose avalanche cycle is expected.
Overnight snowfall will continue on Friday with 20 to 50 cm of new snow expected. Precipitation will transition to rain on Friday, soaking the upper snowpack. In the high alpine, snow may remain dry and will be redistributed by strong southerly winds.
A weak facet/crust layer can be found down 50 to 100 cm. The remainder of the snowpack is strong, with numerous hard melt-freeze crusts.
Treeline snow depth ranges from 100 to 180 cm. Snow depth diminishes rapidly at low elevations where there has been more rainfall.
Thursday Night
Cloudy with snowfall, 15 to 40 cm of accumulation. Alpine wind southeast 40 to 60 km/h. Treeline temperature rising to -4 C.
Friday
Cloudy with snowfall turning to rain in the morning. 10 to 50 mm of precipitation, heaviest on the west island. Alpine wind south 50 to 80 km/h. Treeline temperature rises to 3 °C, freezing level rising to 2300 m.
Saturday
Cloudy with light precipitation falling as rain below 1800 m, up to 5 mm. Alpine wind south 15 to 30 km/h. Treeline temperature 1 °C, freezing level around 1800 m.
Sunday
Cloudy with light precipitation falling as rain below 1800 m, up to 5 mm. Alpine wind south 15 to 30 km/h. Treeline temperature 1 °C, freezing level around 1800 m.
More details can be found in the Mountain Weather Forecast.
