Reactive wind slabs may build through the day on north through east aspects at upper elevations.
New snow accompanied by strong south winds will build fresh and reactive wind slabs on lee slopes at treeline and above.
Wet loose avalanches are possible where precipitation falls as rain at lower elevations.
A weak layer from January, consisting of a melt-freeze crust with facets, is being tested by heavy loads from snow, rain, and warming. This layer could be a concern in the south and east ends of the region in shallower snowpack areas.
On Tuesday, a size 3.5 persistent slab avalanche was observed from a north aspect in the alpine. This likely failed last weekend.
New snow and wind on Thursday may build isolated, yet reactive wind slabs at upper elevations on leeward (north though east) facing slopes.
Thank you for sharing your observations to the MIN.
Rain and warming to mountaintop have saturated the upper snowpack on all aspects and elevations, except high north-facing alpine slopes. As freezing levels fall Thursday, a widespread crust will form. New snow accompanied by strong south wind will likely build wind slabs at upper elevations. Expect deeper and more reactive deposits on north and east-facing slopes.
Below 1800 m, the snowpack has shrunk considerably.
A weak layer of facets and surface hoar from February is now 90 to 150 cm deep and a layer of facets and surface hoar from late January is 110 to 190 cm deep. Some recent planar results were reported in the Manning Park area.
Below this, the snowpack is well-settled and strong.
Wednesday Night
Cloudy with light rain 5 to 10 mm. 15 to 35 km/h south ridgetop winds. Treeline temperature 3 °C. Freezing level dropping to 1500 m.
Thursday
Mostly cloudy with some sunny periods and light rain/ snow 5 to 10 mm. 20 gusting to 60 km/h south ridgetop winds. Treeline temperature 4 °C. Freezing level 1900 m.
Friday
Mostly cloudy with 10 to 20 mm falling as snow above 1400 m. 50 km/h south ridgetop winds. Treeline temperature 3 °C. Freezing level 1600 m.
Saturday
Cloudy with sunny periods. 20 to 30 km/h south ridgetop winds. Treeline temperature 1 °C. Freezing level 1000 m.
More details can be found in the Mountain Weather Forecast.
