Watch for fresh storm slabs building throughout the day. Be aware of the potential for large avalanches due to the presence of a buried weak layer.
A weak layer of faceted grains above a hard melt-freeze crust may be found around 40 to 80 cm deep. Last week this layer produced large avalanches. The problem is most prevalent on north to northeast aspects between 1600 m and 2100 m.
Fresh storm slabs will likely be reactive as the new snow is not expected to bond well to the old surface. They are most likely to be triggered in deeper deposits of freshly wind loaded snow.
Sunday night: Snowfall 5-15 cm, 40-60 km/h southwest wind, alpine temperature -5 C. Freezing level 1200 m.
Monday: Snowfall, accumulation 10-20 cm, 40-60 km/h southwest wind, alpine temperature -4 C. Freezing level 1400 m.
Tuesday: Snowfall 15-25 cm, 30-50 km/h southwest wind, alpine temperature -5 C. Freezing level 1300 m.
Wednesday: Overnight snowfall 5-15 cm then cloudy, 10-20 km/h southwest wind, treeline temperature -7 C. Freezing level 1300 m.
On Saturday, a few skier controlled size 1 loose dry and soft wind slab avalanches were reported.
Persistent slab activity has dwindled since last week. The most recent activity was on Tuesday when two avalanches were triggered by riders on northeast aspects at treeline and alpine elevations, similar to the trend of previous avalanches. It remains possible that humans could trigger this layer, where it exists.
New snow and southwest wind have likely formed wind slabs in lee terrain features. The snow accumulates over a thin layer of variably wind affected, faceted snow or surface hoar that overlies a hard melt-freeze crust found on all aspects below around 1500 m and on sun-exposed slopes into the alpine.
Around 40 to 80 cm deep, a weak layer of sugary faceted grains may be found above a melt-freeze crust that formed in February. This layer has been most prevalent on north to northeast aspects between 1600 m and 2100 m. Check out this forecaster blog for more info. The current storm will provide us with feedback on the reactivity of this layer.
There are no deeper concerns at this time.
