Heavy precipitation is forecast overnight as freezing levels spike and then cool. Avalanche hazard will peak with the onslaught of 40-70 mm in 24 hrs - either as a storm slab or wet avalanche problem.
A crust with weak, facetted snow above and below is buried by roughly 50-150 cm of snow. This layer is unlikely to be human-triggered, this current rapid and heavy load of snow/water will stress the snowpack and may provide more insight into the dormancy of this deeper instability.
Upwards of 50 cm snowfall possible above 2000 m. Reactive slabs will build where dry snow prevails. Be especially cautious transitioning into wind-loaded terrain, more reactive deposits lurk in leeward features.
Freezing levels are forecast to spike overnight with moist surface snow reaching the alpine. The wet avalanche hazard will be highest Monday morning at all elevations and persist until the snowpack has frozen again.
Through Saturday, explosives and skier traffic produced multiple size 1-2 storm slabs in treeline terrain and higher, on average crowns were 30 cm deep. Later in the day skiers remotely triggered (size 1) a re-loaded slope at treeline. Loose wet avalanches were reported below 1700 m.
With heavy precipitation (40-70 mm) forecast overnight along with falling freezing levels, it's possible heavy snowfall could blanket upper elevations and quickly build a reactive slab by Monday morning.
Please continue to post your observations and photos to the Mountain Information Network.
Upwards of 40 cm of storm snow over the weekend has been redistributed by strong south winds. Warm temperatures and rain have impacted most elevations, a melt-freeze crust has formed below 1800 m. The new snow covered a layer of weak and unconsolidated snow produced by the recent cold weather.
A number of layers persist deeper in the snowpack, consisting of facets, surface hoar, and crusts. Most recently, these layers have been unreactive and this heavy load of new snow should provide insight into any deeper instabilities. Total snow depths are roughly 90-140 cm at treeline and up to 200 cm in the alpine.
Sunday Night
Rain and wet flurries, 30-40 mm. Ridgeline low temperature 0 C. South wind 50-70 km/hr. Freezing level spiking above 2400 m and dropping to 2000 m by dawn.
Monday
Depending on freezing levels and the snow-rain line, upwards of 50 cm is possible above 2000 m by noon Monday along with strong southwest wind.
Rain and wet snow with cooling through the day, 30-35 mm. Ridgetop high temperature +2 C. Southwest wind 30-50 gusting to 70 km/hr. Freezing level dropping below 1500 m by end of day.
Continued precipitation and high freezing levels will produce a variety of frozen water forms including freezing rain at roadside elevations.
TuesdayWet flurries, 20-30 mm Ridgetop low temperature - C. Southeast wind 30-50 km/hr. Freezing level 1500 m.
WednesdayFlurries, 10 cm. Ridgeline high temperature -2 C. Southwest wind 20-40 km/hr. Freezing level falling to valley bottom.
More details can be found in the Mountain Weather Forecast.
