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RegisterMar 22nd, 2020–Mar 23rd, 2020
South Columbia.
New snow drifted by wind may form reactive slabs at upper elevations. Anticipate changing conditions and monitor the depth, cohesiveness, and bond of the new snow to the old snow surface.
Sunday night: Cloudy, up to 5 cm of snow, light southwest wind gusting moderate near ridge-tops, alpine temperature -5 C, freezing level 1000 m.
Monday: Cloudy, 5-10 cm of snow, light southwest wind, alpine temperature -5 C, freezing level 1500 m.
Tuesday: Mostly cloudy, 5-10 cm of snow, light southwest wind, alpine temperature -7 C, freezing level 1300 m.
Wednesday: Mix of sun and cloud, light west wind, alpine temperature -9 C, freezing level 1100 m.
Over the past several days, avalanche activity was reported as natural loose wet avalanches (size 1-2) running in steep, sun-exposed terrain. Cornices were also observed failing naturally, primarily on north, northeast, and east aspects.
Over the past week, slab avalanches releasing on buried surface hoar layers were also been reported. Several were attributed to peak warming on solar aspects. These avalanches occurred between 1700 m and 2300 m and were breaking 40-100 cm deep. See this MIN report for a helpful illustration.
If you decide to travel in the backcountry, consider sharing your observations via the Mountain Information Network (MIN) to supplement our data stream as operators are shutting down. A conservative mindset and margins are recommended at this time.
5-15 cm of new snow is forecast to accumulate by Monday afternoon. Moderate southwest winds at ridge-tops may build wind slabs primed for human triggering on lee features.
The new snow is falling on a variety of snow surfaces, consisting of sun crusts, hard wind-affected snow, and soft faceted snow. There have also been reports of surface hoar forming on sheltered, shady slopes. See this MIN for a helpful illustration from nearby Glacier National Park. It will be important to track the depth, cohesiveness, and bond of the new snow to these various old snow surfaces across aspects and elevations where you're travelling.
Cornices are large and looming. Two layers of buried surface hoar can be found buried 20-40 cm deep (March 10) and 60-120 cm deep (February 22). Though there is a low likelihood of triggering an avalanche on these layers, the consequences of doing so would be high.