Fresh storms slabs have been touchy and will continue to grow deeper with new snow and wind Tuesday. 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 have been touchy and showed wide propagation on Monday. They will likely remain reactive as they increase in size with new snow and wind Tuesday. They are most likely to be triggered in deeper deposits of freshly wind loaded snow or in wind-sheltered areas where they sit over a weak layer of surface hoar.
Monday night: Snowfall, accumulation 10-15 cm, 40-50 km/h southwest wind, alpine temperature -5 C. Freezing level 1100 m.
Tuesday: Snowfall 10-15 cm, 20-40 km/h southwest wind, alpine temperature -6 C. Freezing level 1300 m.
Wednesday: Overnight snowfall 5-10 cm then cloudy, 10-20 km/h southwest wind, treeline temperature -7 C. Freezing level 1300 m.
Thursday: Snowfall bringing 15-25 cm, 30-40 km/h south wind, treeline temperature -5 C. Freezing level 1300 m.
Storm slabs were touchy on Monday. Explosive and skier control work produced size 1-2 storm slabs showing wide propagation, a few of which were triggered remotely or sympathetically.
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 or storm slab avalanches could trigger this layer, where it exists.
New snow has been wind loaded into soft slabs in lee terrain features at upper elevations. 30-60 cm of new snow has accumulated over variable surfaces including surface hoar in shady, wind-sheltered areas a hard melt-freeze crust found on all aspects below 1500 m and on sun-exposed slopes into the alpine.
Around 50 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. We are still awaiting observations from the current storm which will provide us with feedback on the reactivity of this layer going forward.
There are no deeper concerns at this time.
