Recently formed wind slabs are expected to remain reactive to human triggering on Wednesday. Be alert to conditions that change with elevation and use extra caution in wind exposed terrain.
Recently formed wind slabs are expected to remain reactive to human triggering in exposed terrain. These slabs likely overlie a weak faceted surface from the extended cold period and may remain reactive to human triggering for longer than normal.
An offshore ridge of high pressure is expected to build on Wednesday bringing a break in the weather before the next storm system reaches the coast on Thursday night.
Tuesday Overnight: Snowfall 5-10 cm, moderate SW wind, treeline temperature around -4 °C, freezing level around 400 m.
Wednesday: Mainly cloudy with sunny breaks in the afternoon, moderate to light SW wind, treeline high around -3 °C, freezing level around 500 m.
Thursday: A mix of sun and cloud, light variable wind, treeline temperature around -5 °C, freezing level around 400 m.
Friday: Light snowfall/rainfall, moderate to strong SW wind, treeline temperature may reach around 0 °C, freezing level as high as 1200 m.
On Monday, loose dry avalanches up to size 2.5 were reported in the northwest of the region where upwards of 50 cm of recent storm snow had accumulated. No new avalanches were reported in the south of the region where substantially less storm snow had accumulated.
On Sunday, a natural wind driven avalanche cycle was reported. Most of the activity was size 1.5-2 with the largest being a size 2.5 which failed on a NE aspect at 1700 m and was 50 cm thick. Most of the activity was reported on north and east aspects but a report from the far south of the region suggests activity was on all aspects and elevations.
15-30 cm of storm snow typically accumulated over the weekend expect for in the far north where it was closer to 50 cm. In exposed terrain, this recent snow has been redistributed by ongoing moderate to strong SW winds which has formed reactive wind slabs. The recent storm snow overlies a previously wind-affected surface comprised of old hard wind slabs, sastrugi, and areas scoured to the ground or old crusts. Faceting above the old surface from the prolonged cold temperatures may increase the reactivity of newly formed wind slabs which may end up persisting for longer than normal.
The base of the snowpack is composed of crusts and weak faceted grains, particularly in thin snowpack areas. While these layers have generally gone dormant in the region, they still have the possibility of waking up with new snow load or warming, and wind slab avalanches may still have the potential to step down to these deeper layers in isolated areas.
