Evaluate snow and terrain carefully before entering high-consequence slopes
Use extra caution on wind-loaded terrain features where a slab has formed over a crust.
A crust with weak crystals overtop is buried 20 to 30 cm. This problem is specific to areas where a cohesive slab has formed over the layer, for example on wind-loaded features.
On Wednesday this MIN post reported whumpfing and shooting cracks west of White Pass.
On Tuesday, our field team noted a natural size 2 slab avalanche on a north aspect at 1300m. (See photo below). The slab was 20-30 cm deep and failed on facets above a crust, which is the weak layer described in the snowpack summary below.
Reports have been limited, if you head out in the mountains, please consider sharing your observations on the Mountain Information Network.
Recent outflow winds have scoured windward faces in the alpine and loaded lee slopes. We expect it will take a few days for these new slabs to bond.
The primary layer of concern is a layer of weak facets and in some cases surface hoar, overlying a crust. In most areas, it is buried 20 to 30 cm deep, and extends up to 1750 m. Wind slabs are expected to be more reactive where they have formed over this weak layer.
Despite the presence of faceted grains in the lower snowpack, there are no current layers of concern below the crust.
Snowpack depths range from about 70 to 180 cm.
Thursday Night
Clear. 10 to 20 km/h northeast ridgetop winds. Treeline temperature - 25 °C
Friday
A mix of sun and cloud. 20 km/h northeast ridgetop wind. Treeline temperature -26 °C.
Saturday
Partly cloudy, with 0 to 2 cm of snow. 30 km/h variable ridgetop winds. Treeline temperature -25 °C.
Sunday
A mix of sun and cloud. 30 to 40 km/h ridgetop southwest winds. Treeline temperature -15°C,
More details can be found in the Mountain Weather Forecast.
