While spring-like weather has arrived, the snowpack continues to adjust and stabilize. Large persistent slab avalanches remain possible, particularly on steep northerly alpine slopes.
Persistent weak layers of crust, facets, or surface hoar are buried up to 250 cm deep. Triggering is most likely on northerly aspects, or later in the day on sun-exposed slopes when the upper snowpack has been weakened.
Even brief periods of sun can be enough to trigger wet loose avalanches in steep terrain, especially on slopes that have not slid recently.
While details are lacking, a large (~size 3) persistent slab avalanche was remotely triggered on a north-facing alpine slope on Friday. I appeared to occur on a steep, rocky slope with a thin-to-thick snowpack.
Wet loose avalanches continue to be reported daily with the recent warm temperatures and strong sun.
Crusty surfaces are present across most terrain, except in high alpine north-facing areas, where dry, wintry snow can still be found, and isolated wind slabs may linger. On solar aspects and lower elevations, surface crusts are expected to soften and weaken with daytime warming and solar input.
Several persistent weak layers are buried up to 250 cm deep. While triggering these layers is becoming unlikely, they present a low-probability, high-consequence problem. A cornice fall (large load) may be enough to trigger this slab.
Saturday Night
Clear skies. 10 km/h south ridgetop wind. Treeline temperature 1 °C. Freezing level 1400 m.
Sunday
Mostly sunny. 1 mm of precipitation as snow or rain at treeline. 20 km/h southwest ridgetop wind. Treeline temperature 1 °C. Freezing level 1400 m.
Monday
Mix of sun and clouds. 4 to 10 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -2 °C. Freezing level 900 m.
Tuesday
Mostly cloudy. 5 to 15 cm of snow. 30 km/h southwest ridgetop wind. Treeline temperature -4 °C.
More details can be found in the Mountain Weather Forecast.
