New wind slabs should be on your radar, but the weak basal snowpack is a bigger problem. Choose conservative terrain to avoid the consequences of triggering a destructive persistent slab.
Wind slabs could still linger in the alpine. Probably most importantly, if triggered, wind slabs may step down to deeper layers, causing larger, more destructive avalanches.
A faceted lower snowpack presents a persistent slab problem. This basal layer may be triggered by cornice fall or the weight of a rider in shallow snowpack areas or on steep features where the snowpack transitions from thick to thin.
Aerial observations in White Pass on Thursday included several recent natural persistent slabs to size 2.5, mainly on southeast to southwest aspects. There were also numerous wet loose on similar aspects up to size 2 and a few small natural cornice releases triggering small wind slabs. One solar-triggered wind slab stepped down to a persistent weak layer and released a size 2 avalanche.
Check out this MIN report for more detail.
Light flurries will add a skiff of new snow to new surface hoar that has been growing in the high alpine, although forecast winds may damage these unwanted grains on wind-exposed slopes.
New snow will otherwise bury hard, pressed surfaces, wind slab, and sastrugi in exposed terrain. That said, we’ve received reports of good riding on faceted northeast-facing slopes and sheltered terrain at lower elevations. A sun crust on or near the surface of sun-exposed slopes completes the tally of pre-storm surfaces.
The lower snowpack is faceted and generally weak, particularly in shallow areas.
Friday Night
Cloudy, mainly around White Pass, with flurries bringing 1 or 2 cm of new snow. 30 to 40 km/h south ridgetop wind. Treeline temperature around -5 °C.
Saturday
Mostly cloudy with continuing flurries bringing 1 to 3 cm of new snow, still mainly around White Pass. 20 to 30 km/h south ridgetop wind, easing. Treeline high temperature -4 °C.
Sunday
A mix of sun and cloud with isolated flurries. 20 km/h southeast ridgetop wind. Treeline high temperature -4 °C.
Monday
Cloudy with flurries bringing 5 to 10 cm of snow, including overnight. 15 to 40 km/h east ridgetop wind, easing. Treeline high temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
