Spring is a dynamic time of year where conditions can vary widely and change rapidly. Localized convective snowfall can appear out of nowhere and even short periods of strong sun can rapidly destabilize the upper snowpack.
Carefully assess your local conditions and pay attention to how the weather is affecting the snowpack throughout the day.
10 to 30 cm of recent snow arrived with wind, and likely formed deep deposits in leeward terrain features. Rapid settlement caused by periods of strong sun, has the potential to trigger storm slab avalanches.
Loose wet avalanches will become increasingly likely on steep solar aspects as the surface becomes moist or wet with strong sun.
On Friday and Saturday, small (size 1) storm slabs and loose dry sluffing were reactive to skier traffic. Explosive control work on Saturday produce mostly size 1 storm slabs, with a few size 1.5-2. Greatest reactivity has been in wind loaded areas in the alpine.
Prior to the most recent storm, cornices and wind slabs were reactive. Several cornice failures triggered size 2-3 wind slabs in the alpine. Several skier-triggered wind slabs were reported from north and west aspects.
A moist or crusty surface has likely formed on southerly aspects and below 1000 m. 15 to 30 cm of recent snow has likely been blown into deep deposits in leeward terrain features at wind-exposed elevations by previous strong southeast to southwest winds. The recent snow sits over a variety of surfaces that include a heavily wind-affected alpine and treeline and a crust at lower elevations and solar aspects.
The middle of the snowpack is strong and bonded. At the bottom of the snowpack, a layer of weak facets remains present and continues to be monitored for signs of reactivity.
Sunday night
Partly cloudy with convective flurries accumulating a few cm. Alpine low -10 °C. Light northerly wind. Freezing level valley bottom.
Monday
Mostly sunny. Light southwest wind. Alpine high -1 °C. Freezing level rises to 1300 m.
Tuesday
A mix of sun and cloud. Light variable wind. Alpine high -1 °C. Freezing level rises to 1300 m.
Wednesday
Mostly cloudy. Light to moderate southwest wind. Alpine high -5 °C. Freezing level rises to 1000 m.
More details can be found in the Mountain Weather Forecast.
