The next storm arrives Monday night and brings with it an additional 10 - 20 mm of precipitation and strong southerly winds. These conditions will continue to build thick storm slabs that are reactive to human triggering.
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.
Extreme southerly winds have redistributed upwards of 50 cm of new snow into deep pockets at higher elevations. Where snow remained dry expect to find pockets of storm slabs that are reactive to human traffic. Be especially cautious transitioning into wind-loaded terrain, more reactive deposits lurk in leeward features.
On Sunday, explosives control triggered several storm slab avalanches up to size 2.5. Storm slabs were 30-50 cm deep. Explosive also triggered one size 2.5 persistent slab avalanche that is suspected to have run on the Dec 8 surface hoar.
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.
Please continue to post your observations and photos to the Mountain Information Network.
By Tuesday morning 10 - 20 cm of additional snow brings storm snow totals to 40 - 50 cm. Extreme southerly winds have pressed surfaces and redistributed snow into thick slabs in alpine lees. A melt-freeze crust is found 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.
Monday Night
A brief break between storms ends early evening as flurries start up again, 10-20 mm. Ridgeline low temperature -2 C. Southerly winds 25-40 km/hr. Freezing levels around 1100 m.
Tuesday
Moderate to heavy precip, 10-20 mm. Ridgetop high temperature 0 C. Southerly wind 30 - 50 km/h weakening in the afternoon. Freezing levels rise to 1800m during the day before falling to 1000 m overnight.
WednesdayCloudy with scattered flurries, trace accumulation. Ridgetop high temperature -4 C. Westerley winds 20 km/hr. Freezing levels 800-1000 m.
ThursdayCloudy with scattered flurries, trace accumulation. Ridgeline high temperature -4 C. Southerly wind 40 - 60 km/h weakening in the afternoon. Freezing levels 500-1000 m.
More details can be found in the Mountain Weather Forecast.
