Wind slabs and settled snow may be sitting on pockets of reactive surface hoar. Watch for signs of instability like shooting cracks and recent avalanches.
Watch for signs of slab formation in the surface snow, particularly in areas loaded by north winds and where buried surface hoar could be preserved (think sheltered openings at mid elevations).
Surface snow covers a crust and isolated surface hoar which has produced natural, remote and rider-trigger avalanches. Investigate this interface. As the snow settles and gains cohesion, a reactive upper snowpack may form.
Natural and remotely triggered avalanches are still being reported up to size 2.5 in the region at both alpine and treeline elevations, on west, north, and east aspects. These avalanches are often associated with a weak layer of surface hoar that was buried in early January. In some cases, a windslab is sitting above this layer of surface hoar.Thursday and Friday of last week saw similar avalanches being reported to size 2.5.
Roughly 40-60 cm of new snow fell in the region early this week. It buried a mix of crusts, surface hoar, and facets. Areas where surface hoar may be preserved are of greatest concern.
A crust formed by early December rain is found ~70 cm deep, and an old layer of surface hoar is 60-100 cm deep. Recent observations suggest triggering this layer is unlikely. The lower snowpack is variable throughout the region and weak basal facets are likely to be found on the ground in shallow snowpack areas.
Sunday Night
Clear, north alpine wind 20-50 km/h, treeline temperature -26 °C.
Monday
Mostly sunny, west alpine wind 10-50 km/h, treeline temperature -20 °C.
Tuesday
Cloudy with up to 5 cm of snow, Southwest alpine wind 10-30 km/h, treeline temperature -16 °C.
Wednesday
Cloudy with 10-15 cm of snow, south alpine wind, 10-40 km/h, treeline temperature -12 °C.
More details can be found in the Mountain Weather Forecast.
