New snow builds fresh, reactive storm slabs over weak surfaces and adds load to deeper buried weak layers. If you see more than 25 cm of new snow, treat avalanche danger as HIGH.
Buried persistent weak layers have produced large natural and human-triggered avalanches recently. Additional snow load may increase sensitivity to triggering.
New snow is expected to bond poorly to old surfaces including crusts and widespread surface hoar. Storm slabs are most likely to fail in wind loaded areas where sufficient snow has been deposited to overload the weak interface.
Persistent slabs were reactive on the February weak layer earlier this week, predominantly in the alpine. Naturals up to size 3, explosive controlled up to size 3.5 and skier remotes up to size 2.5 triggered from 100 m away. By Wednesday, reports of avalanche activity tapered dramatically.
Looking forward, new snow means an increase in likelihood of both surface avalanches as well as renewed possibility of large persistent slab avalanche activity.
New snow accumulates over a widespread layer of large surface hoar crystals, which sit over a crust on solar aspects and low elevations.
A layer of facets, surface hoar and/or a crust from mid February are buried 50 to 100 cm deep. This layer produced large natural and human-triggered avalanches earlier this week.
The remainder of the snowpack is well consolidated with no concerns at this time.
Forecast snowfall amounts are highest on the immediate coast, tapering sharply as you travel inland.
Thursday night
Cloudy with 5 to 10 cm of snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperatures -5 °C. Freezing level 700 m.
Friday
Mostly cloudy with 10 to 20 cm of snow. 40 to 60 km/h south ridgetop wind. Treeline temperatures -3 °C. Freezing level 1200 m.
Saturday
Mostly cloudy with 1 to 5 cm of snow. 20 to 30 km/h south ridgetop wind. Treeline temperatures -6 °C. Freezing level 800 m.
Sunday
A mix of sun and cloud. 10 to 20 km/h south ridgetop wind. Treeline temperatures -7 °C. Freezing level 800 m.
More details can be found in the Mountain Weather Forecast.
