Ongoing snowfall and elevated winds will test the deep snowpack and create dangerous avalanche conditions on Tuesday. Stick to simple terrain that is free of overhead hazards.
Forecast snowfall and wind will be forming new slabs through Tuesday. Wind affected areas should be the most sensitive to triggering, but sheltered spots around treeline where surface hoar may be buried are suspect.
Basal facets remain a real concern in steep, rocky terrain and other alpine features with thin-to-thick snowpack transitions. Recent avalanche activity tells us this problem is still lurking out there.
A size 2 (large) deep persistent slab was triggered from a 20 m distance in the Clemina alpine on Sunday on a NE aspect. It was 70 cm deep, failing at the base of the snowpack. This underscores that basal snowpack structure remains a real problem in the region.
Many natural size 1-1.5 (small) storm slabs were observed in the Blue River area Saturday. These involved only 20-30 cm of new snow.
Moderate snowfall and elevated winds Tuesday should reinvigorate avalanche activity.
Roughly 15-25 cm of new snow should accumulate in the region by end of day Tuesday. It will bury somewhat wind-affected snow in exposed areas at elevation and otherwise add to about 50 cm of recent storm snow.
This older snow is settling and gradually bonding to a variety of old surfaces. Sheltered terrain where it buried surface hoar is where its bond is most suspect. It overlies a crust below about 1600 m.
Two additional surface hoar layers in the top 1.5 m of the snowpack are diminishing in importance. The deeper of the two likely has a robust crust above it below treeline.
The depth of the snowpack varies greatly throughout the region and weak basal facets are present at the base of the snowpack.
Monday night
Cloudy with flurries bringing 5-15 cm of new snow. Southwest alpine wind 10 to 15 km/h, treeline temperature -11°C.
Tuesday
Cloudy with continuing flurries bringing 5-15 cm of new snow, continuing again overnight. South alpine wind 10-30 km/h, easing. Treeline temperature -9°C.
Wednesday
Clearing, still mainly cloudy, with up to 10 cm of new snow from the overnight period. Northwest alpine wind 5-15 km/h. Treeline temperature -15°C.
Thursday
A mix of sun and cloud with a trace of new snow from overnight. Northeast alpine wind 10-25 km/h. Treeline temperature -28°C.
More details can be found in the Mountain Weather Forecast.
