Watch for signs of wind slabs on all aspects as wind direction is expected to reverse on Tuesday. Buried persistent weak layers also remain a concern and avalanches have the potential to step down to a deeper layer.
Summary
Confidence
Moderate - Wind speed and direction is uncertain
Weather Forecast
Mostly cloudy conditions are expected Tuesday morning with the possibility of lingering flurries. Mostly sunny conditions are expected by Tuesday afternoon. Treeline temperatures are expected to fall to around -20C and alpine winds are forecast to be moderate to strong from the north. Sunny conditions are expected for Wednesday and Thursday with treeline temperatures around -15C during the afternoon and -25C overnight. Alpine winds are forecast to be light from the northeast on Wednesday and moderate from the northwest on Thursday.
Avalanche Summary
No new avalanches were reported on Saturday or Sunday. On Tuesday, recently formed wind slabs are expected to remain reactive to human triggering. Ongoing wind loading is also expected on Tuesday with the forecast for moderate to strong northerly winds in the alpine. With the winds switching directions, wind slabs should be expected on a variety of aspects. Persistent slab avalanches also remain an ongoing concern. Buried weak layers are creating a low probably, high consequence problem for the region.
Snowpack Summary
10-20 cm of new snow has covered a layer of surface hoar that was growing on the surface before January 6. Below the surface, recent cold temperatures have been promoting faceting of the upper snowpack. In exposed areas at all elevations, recent winds have scoured windward slopes and formed hard wind slabs in unusual places as the winds shifted from west to northeast. Continued moderate variable winds have been keeping wind slabs fresh and touchy in some areas. The layer of facets and surface hoar that was buried mid-December has been giving hard and broken results or non-results in snowpack tests where it is found around a metre below the surface. Snowpack tests in shallower areas, however, have yielded moderate sudden planar results on this persistent weakness, suggesting the primary concern for persistent slab avalanches is in shallow snowpack areas. With that said, the potential for a wind slab avalanche to step down to this weak layer remains a concern where it lies deeper in the snowpack. The lower snowpack is well bonded and features a thick rain crust near the ground.
rbuhler,
Avalanche Canada
