There's a lot at stake in avalanche terrain right now with enough new snow for large avalanches and the mercury dropping. Check out our Forecasters' Blog for tips on managing the cold.
Cool temperatures should work to preserve low density snow conditions and may allow riders to trigger powerful dry loose avalanches in steep terrain.
Watch for signs of slab formation in the new snow, particularly in areas loaded by north winds and where buried surface hoar could be preserved (think sheltered openings at mid elevations).
Initial reports suggest it was a busy day for avalanches Tuesday.
Like after Saturday's storm, we're seeing a mix of numerous storm slab, wind slab, and dry loose avalanches, mainly to size 1.5 (small) but with a good number of size 2 (large) releases as well. Persistent slabs have not figured into reports.
Looking forward to Thursday, expect new snow to remain sensitive to triggering where north winds drive new wind slab formation and where surface hoar may be preserved.
Roughly 30-50 cm of new snow fell in the region early this week. It buried moderately wind-affected surfaces in exposed areas at elevation, but mainly added to 30-60 cm of storm snow from Saturday. All this snow collectively sits on an aspect and elevation-dependent mix of crusts, surface hoar, and facets. Areas where surface hoar may be preserved are a concern.
A crust formed by early December rain is found ~70 cm deep, and an old layer of surface hoar 60 to 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.
Wednesday night
Mainly cloudy. West or northwest alpine wind, 15-30 km/h.
Thursday
A mix of sun and cloud with isolated flurries. Variable, mainly northwest wind 5-25 km/h. Treeline temperature -20°C to -25°C.
Friday
Sunny. North alpine wind 5-15 km/h. Treeline temperature -30°C.
Saturday
Sunny. Variable alpine wind 5-10 km/h.
More details can be found in the Mountain Weather Forecast.
