Stormy conditions on Monday night will produce dangerous avalanche conditions for Tuesday.
Snow and strong wind on Monday night will add to the 40 to 80 cm of snow that recently accumulated. Both storm slabs and wind slabs could be triggered on Tuesday, particularly in wind-exposed terrain and where all this snow overlies weak surface hoar crystals.
A layer of large and weak facets sits near the base of the snowpack. This layer is most prominent in upper treeline and alpine elevations and continues to produce sporadic, destructive avalanches. Human-triggering is most likely on steep, shallow, rocky slopes.
Small wind slabs were triggered by riders on Sunday as the recent snow was redistributed by wind.
On Saturday, explosives triggered a few large (size 2 to 3) deep persistent slab avalanches 200 cm deep on north to east aspects between 1900 and 2300 m.
Looking forward, large storm and wind slabs could be human-triggered within all the recent storm snow. Wind slabs could rapidly form on atypical aspects due to northeast wind on Tuesday.
Monday night's storm snow will add to the 40 to 80 cm of recent storm snow, which may sit on a small layer of surface hoar crystals in wind-sheltered terrain. In wind-exposed terrain, the snow is being redistributed into wind slabs and large cornices. The wind was predominantly southwest but is switching to northeast, meaning that wind slabs may be found on all aspects.
The mid-pack is generally strengthening. A spotty surface hoar layer may be found about 80 to 150 cm deep. This layer is most likely found in openings around treeline elevations that are sheltered from the wind. The layer hasn't produced recent avalanches.
Large and weak facets that formed in November are found near the base of the snowpack. A cornice fall is a likely trigger for this layer.
Monday Night
Cloudy with snowfall, accumulation 15 to 25 cm, 20 to 40 km/h southwest wind, treeline temperature -14 °C.
Tuesday
Mostly cloudy with isolated snowfall, accumulation 1 to 3 cm, 30 km/h northeast wind, treeline temperature -20 °C.
WednesdayMix of sun and cloud with no precipitation, 20 km/h northeast wind, treeline temperature -25 °C.
ThursdayMix of sun and cloud with no precipitation, 20 km/h northeast wind, treeline temperature -26 °C.
More details can be found in the Mountain Weather Forecast.
