Wind slabs will remain triggerable by riders Friday. Shooting cracks in stiffened or drifted snow are good indicators of reactive wind slab. Be mindful that deep instabilities still exist and have recently produced very large avalanches.
Recent snow and wind have formed deep wind deposits in leeward terrain features. They will likely remain reactive on Friday. Watch for shooting cracks in stiffened or drifted snow as an indicator of instability.
A weak layer of surface hoar and/or facets buried ~100 cm deep has produced occasional large, widely propagating avalanches on north to east aspects above 1500 m. Some avalanches have been remotely triggered from hundreds of meters away! A layer at this depth may not show obvious signs of instability. Best to avoid steep or unsupported high consequence alpine terrain.
Since the storm cleared up on Thursday, our field team has observed a natural avalanche cycle up to size 3 from the highway. We suspect that some of these may include step-downs to buried weak layers.
Our field team recently observed a large natural wind slab avalanche that stepped down to a deeper weak layer in the Paddy Peak area, likely during the outflow winds last weekend.
30-50 cm of recent snow has been stiffened at the surface and transported into wind slabs by moderate winds at upper elevations. At lower elevations, the recent snow has settled in Thursday's mild temperatures.
In the mid snowpack, a couple of crusts buried 60+ cm and 100+ cm deep have been problematic on north to east aspects as high as 1700 m, where they are covered in an overlying layer of weak surface hoar crystals. Recent large avalanches are suspected to have run on the deeper of the two layers. On the bright side, recent snowpack tests by our field team suggest that these layers are beginning to strengthen and bond.
Thursday night
Flurries bringing up to 5 cm. Moderate southerly wind. Alpine low -12 ºC.
Friday
Cloudy with sunny breaks. Light northeast wind picking up in the evening. Alpine high -15 ºC.
Saturday
A mix of sun and cloud. Moderate to strong northeasterly outflow wind. Alpine high -19 ºC.
Sunday
Mostly sunny. Strong northeasterly outflow wind. Alpine high -21 ºC.
More details can be found in the Mountain Weather Forecast.
