Storm slabs will likely remain sensitive to human triggering especially in deep wind-loaded pockets in alpine lees. Fresh snow will shed easily from steep slopes that see periods of direct sun exposure Monday.
Natural cornice falls have been reported recently and will likely increase with sun exposure on Monday. Cornice falls are dangerous in their own right but they may also trigger avalanches on slopes they impact.
This problem will likely be focused in wind loaded lees of exposed terrain features. Fresh accumulations are likely to shed easily from steep slopes that see sun.
Sunday night: Clear periods with possible flurries. Light northwest winds. Alpine low -12 C. Freezing level valley bottom.
Monday: Mix of sun and cloud with possible flurries. Light northwest winds. Freezing level 900 m.
Tuesday: Mix of sun and cloud. Light northwest winds. Freezing level valley bottom.
Wednesday: Sunny. Light northwest winds. Freezing level 700 m.
Explosive control work conducted on Sunday produced mostly loose avalanches up to size 1.5 with limited slab property in storm snow. Reports from Saturday consisted of small (size 1) natural cornice/slab and skier triggered wind slab avalanches. On Friday, several natural and explosive triggered storm slabs reached size 2, with crown fracture depths of 20-40 cm. Wind-loaded northeast aspects above 1900 meters featured most prominently. Several natural cornice falls were another stand-out feature.
20-30 cm of snow from the past week has been blown into wind slabs and cornices. In sheltered areas, the recent snow is settling and may contain sun crusts and layers of surface hoar.
A thick rain crust sits 30-60 cm below the surface, up to 2100 m. Recent reports indicate that faceting may be occurring at the interface of this crust and overlying snow in some areas. A weak layer sitting between a dense slab and a slick bed surface is a recipe for a future persistent avalanche problem.
The bottom 20 cm of the snowpack consists of basal facets and decomposing crusts that have not been an active avalanche problem since December, but could reemerge as a problem after sustained warming.
