Avalanche hazard is decreasing, but a buried persistent weak layer can still produce large, destructive avalanches.
Stubborn wind slabs may lurk around ridges and in lee terrain. Check for wind-loaded pockets below ridgelines and in cross-loaded features.
Facets in the mid and lower snowpack are most likely to be triggered in steep, rocky, wind-affected areas where the snowpack transitions from deep to shallow areas.
A large, rider-triggered persistent slab avalanche occurred last Sunday on the east side of White Pass. Behind the Big Y, a snowmobiler triggered a size 2 avalanche on a west-facing alpine slope near a thin rocky area. The avalanche failed on facets near the ground.
More recently, evidence of natural wind slab avalanches has been observed. Wind slabs may remain reactive to riders with ongoing wind and snow transport.
Strong winds have left stubborn wind slabs and wind-affected surfaces. Up to 30 cm of facetted and settling powder is found in sheltered areas and lee features; this covers old wind-affected snow.
Prolonged cold temperatures this winter have resulted in a very faceted mid to lower snowpack. Normally, thick and stiff wind-hardened layers would lower the likelihood of triggering these facets, but these layers are lacking their usual strength. Thick to thin upper treeline or lower alpine features are the most likely place to trigger weak layers in the mid and lower snowpack.
Cornices are large and looming. A large cornice fall could trigger persistent layers deeper in the snowpack.
Friday Night
Clear skies. 20 km/h northeast ridgetop wind. Treeline temperature -16 °C.
Saturday
Mix of sun and clouds. 10 km/h northeast ridgetop wind. Treeline temperature -17 °C.
Sunday
Mix of sun and clouds. 10 km/h south ridgetop wind. Treeline temperature -15 °C.
Monday
Mix of sun and clouds. 10 km/h southwest ridgetop wind. Treeline temperature -13 °C.
More details can be found in the Mountain Weather Forecast.
