Wind slabs may remain reactive to human triggers; especially in high elevation, north facing terrain that is steep, rocky, and/or has a highly variable snowpack depth.
Weather Forecast
WEDNESDAY NIGHT: Cloudy with isolated flurries; 3-10 cm. / Light, southwesterly winds / Alpine low -5 C / Freezing level 1000 m.THURSDAY: Mostly cloudy with isolated flurries; trace-3 cm. / Light, northwesterly winds / Alpine high -4 C / Freezing level 1500 m.FRIDAY: Mix of sun and cloud / Light, southerly winds / Alpine high -3 C / Freezing level 1700 m.SATURDAY: Snow in the mountains and rain in the valleys; 3-5 cm. / Light to moderate, southwesterly winds / Alpine high -3 C / Freezing level 1600 m.
Avalanche Summary
On Tuesday, a small (size 1) slab avalanche 30 cm. deep was remotely triggered by a skier from 80 m. away on a northeast aspect at 2250 m. A layer of small surface hoar below the most recent snow may have been the weak layer. Additionally, several loose wet avalanches up to size 1.5 where triggered on solar aspects throughout the day by strong solar radiation.On Monday there was quite a bit of natural avalanche activity in the recent storm snow. Slabs to size 1.5 were reported from all aspects between 1800 and 2700 m. The natural activity was likely caused by the appearance of the strong April sun.On Sunday wind slabs to size 2 released naturally and were also susceptible to human triggering on north, northeast and east facing terrain between 1900 and 2200 m.
Snowpack Summary
Last week's unsettled weather produced 15-30 cm of snow in the alpine which tapers rapidly with elevation. This snow is sitting on a melt-freeze crust on all aspects except for northerly slopes above 1800 m, where it sits on dry snow and possibly small surface hoar (weak, feathery crystals) in isolated locations. I suspect high elevation, north facing terrain where wind slabs may be sitting on small surface hoar would currently be the most likely place to trigger a slab avalanche.Snow is disappearing rapidly at lower elevations.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.