The eastern slopes of the Rockies are the place to be this week! New snow should stay deep and light with continued cold temperatures and light wind. Be alert to signs of slab property and instability at wind-exposed elevations and mind your sluff in steep terrain.
Soft, fresh wind slabs may be found in unusual terrain features due to reverse loading by irregular wind direction. Wind slabs may sit over a sun crust on solar aspects and a rain crust below 2100 m. Crusts make a slick bed surface for avalanches.
Tuesday night: Flurries bringing up to 10 cm. Light northeast wind. Alpine low around -16 °C.
Wednesday: A mix of sun and cloud. Light northwest wind. Alpine high around -13 °C.
Thursday: A mix of sun and cloud. Moderate northwest wind. Alpine high around -8 °C.
Friday: A mix of sun and cloud. Moderate west wind. Alpine high around -3 °C. Freezing level rising to 1500 m.
Observed avalanche activity on Tuesday was limited to size 1 skier triggered storm slab and loose dry avalanches. Little wind effect or slab property was observed in the new snow.
On Sunday, explosive control work near Elkford produced cornice, storm slab and loose dry avalanches size 1.5-2.5 on north aspects in the alpine. Good visibility allowed observation of 2-3 day old storm slabs up to size 2.5 in the Castle backcountry. In neighboring Waterton National Park, ski cuts produced storm slabs and loose dry avalanches up to size 1.5.
On Friday and Saturday, avalanche activity was predominantly loose dry up to size 1.5.
The southeast corner was the winner again yesterday with 20-40 cm on the eastern slopes of the range. Elsewhere, closer to 10 cm (if any) new snow sits over a crust on steep south facing slopes and below 1500 m. The new snow has likely seen a bit of wind effect in exposed terrain at upper elevations.
Last week's snowfall amounts also varied widely through the region with as much as 50 cm in the south and as little as 10 cm in the north. Below 2100 m, a rain crust exists embedded within this snow. Below, a variety of old surfaces include a sun crust on solar aspects, and potentially weak, sugary crystals in shady areas.
The middle and lower snowpack are generally well consolidated, with a crust/facet layer from early December found near the ground. It is currently considered dormant but could become active later this season.
