Clear skies for the next few days and a slight inversion is possible on Saturday morning. Uncertainty regarding the Jan 3 peristent layer is keeping the below treeline rating at moderate.
A thin temperature surface crust extends up to 2600 m and is more pronounced on solar aspects. Still skiable...
30-60 cm new snow over the last few days with moderate to strong westerly winds has formed windslabs in exposed alpine and treeline areas. These have been less reactive than expected but could still surprise you.
Surface hoar buried January 3 sits 30–100 cm deep. This layer now has a slab & a thin surface crust over it. It is a prime depth for skier triggering. While not widespread, recent reports include small avalanches failing on this layer with potential to propagate. Dig down and test for reactivity.
Basal facets remain near the ground. Red flags are fewer where the snowpack is deep, but on the eastern side of the forecast area, particularly in thin to thick snowpack transitions, the potential for deep slab avalanches remain.
Jan 15 flight showed widespead natural wind slabs & cornice failure to size 2 from the past week; few deep releases observed, though the east side of the region was not observed. One MIN described a deep release near Cirque Peak.
Jan 14: a skier-triggered size 1 near Sunshine at 2300 m on the Jan 3 persistent weak layer, and the same layer also reacted in tests on Mount Field at 2100 m (on Jan 15).
Explosive control in Yoho triggered windslabs generally size 2 with some up to size 2.5.
Field teams report a variable thickness melt-freeze surface crust to ridge top, and widespread wind effect in the alpine. Under the crust, the snowpack feels firm, but in isolated locations (Sunshine, Mt. Field), the January 3rd surface hoar layer is reactive down 30-100 cm. The November facet/crust interfaces is 20 - 40 cm up from the ground.
Thursday night: Clear. Alpine temperature: Low -10°C, Strong northerly winds tapering to moderate
Friday: Mostly sunny. Alpine high -5°C. Ridge winds northerly 10-30 km/hr.
Saturday: Mostly Sunny. Slight alpine temperature inversion in the morning (0°C at ridge top and -2°C in the valley bottom). Ridge wind light to moderate northerly wind. Freezing level rises to 1500 m.
