A buried surface hoar layer may become more reactive as storm snow accumulates. Approach steep open slopes at treeline and below with caution.
Watch for signs of instability as you travel. Consider conservative terrain choices as a way to manage uncertainty.
Fresh wind slabs may build with continued strong westerly winds and new snow. Expect reactivity where they overly a smooth crust, or a weak surface hoar layer in sheltered terrain features.
Look for wind loading in unusual places, as direction has varied from northwest to southwest and stronger wind speeds may load mid slope features.
Fresh snow sits over a large surface hoar layer. On south facing aspects this may sit on a crust. Treat open slopes at treeline and below with caution - they may be more reactive and produce larger avalanches than you expect. Shooting cracks or whumpfing are clear signs to keep terrain choice conservative.
Light snowfall is forecast for Friday. Temperatures rise and skies clear for the weekend.
THURSDAY NIGHT: Cloudy with moderate westerly winds. Freezing level at valley bottom. Scattered flurries.
FRIDAY: Cloudy with 5 -15 cm of low density snow. Strong westerly winds. Freezing level 1000 m, alpine high of -5.
SATURDAY: Mostly clear with cloudy periods, a chance of flurries. Moderate westerly winds. Freezing levels around 1500 m, alpine high of -3.
SUNDAY: Mostly clear with moderate westerly winds. Freezing levels rise to 2000 m, alpine high of 0.
Recent avalanche activity has been limited to small loose dry avalanches out of steep terrain features.
Shooting cracks and whumpfing have been reported by industry operators and in several MIN reports. This indicates the buried surface hoar layer is sensitive to human triggers.
On Monday, a size 2.5 natural persistent slab avalanche was reported to have occurred on a path that had previously avalanched where storm snow reloaded bed the surface.
At lower elevations up to 40 cm of storm snow sits over a melt freeze crust. In sheltered terrain a layer of large surface hoar crystals may sit immediately above the crust, sensitive to human triggers.
At higher elevations the storm snow has been redistributed by moderate to strong westerly winds. A thin melt freeze crust extends into the alpine on solar aspects. This crust may sit on the surface or below wind deposited snow.
The widespread January 18 rain crust is now around 40-50 cm deep with weak faceted snow above, however it has not produced recent avalanche activity.
The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous large avalanches in January, and is now considered dormant. We will continue to track this layer of concern and expect it will wake up again with major warming or a large storm event. This recent forecaster blog goes into more details on the layer.
