Recent snow, winds, and buried weak layers make a complex recipe for avalanche hazard.
Fall back on conservative decision making!
Wind slabs have likely formed on slopes lee to southwest winds, and lee features like ridges and gullies. Wind slabs may be more reactive where they overlie buried weak layers, such as surface hoar, now buried 30 to 100 cm deep.
Yesterday a large natural avalanche cycle occurred. Numerous wind slab avalanches, up to size 3, were reported throughout the region. These avalanches mostly occurred on lee slopes or lee features.
Explosive control work in the north of the region produced numerous slab avalanches, up to size 3. One of these avalanches was reported to have failed on buried surface hoar, 50 cm deep.
Near Stewart, several natural wet loose avalanches were reported at low elevations.
Approximately 20 to 45 cm of new snow has been redistributed by strong south and southwesterly alpine winds. Recent snow may have buried a layer of weak, feathery surface hoar crystals. Another layer of buried surface hoar may exist deeper in the snowpack, roughly 50 to 90 cm below the surface.
The remaining mid and lower snowpack contains several crusts from early in the season that are generally well-bonded to the surrounding snowpack.
Currently, the height of snow is highly variable and decreases significantly at lower elevations.
Thursday Night
Mostly cloudy with no precipitation, southwest alpine winds 30 to 60 km/h, treeline temperature -12°C.
Friday
Cloudy, with 2 to 20 cm of snow possible, southwest alpine winds 40 to 60 km/h, treeline temperature around -2°C, freezing level rising to 700 m at Shames and 1000 m at Mt Claugue.
Saturday
Partly cloudy with trace amounts of snow possible, variable direction alpine winds 10 - 20 km/h, treeline temperature around -8°C, freezing level returns to valley bottom at Shames.
Sunday
Cloudy with 2 to 5 cm of snow, southwest alpine winds 20 to 40 km/h, treeline temperature around -8°C.
More details can be found in the Mountain Weather Forecast.
