Additional snow from the incoming storm is likely to increase reactivity on previously buried surface hoar. Be cognizant of increasing hazard, especially on wind loaded features.
Both south and north winds have redistributed new and available snow into fresh wind slabs in exposed lee terrain features at higher elevations. A buried layer of surface hoar is increasing the reactivity and propagation of wind slabs.
A weak layer of large surface hoar is found down 20-50 cm. This layer has been most active in the Shames region however with additional load we may see wider spread reactivity on this layer. Use caution on sheltered and shaded slopes where surface hoar is more likely to be preserved.
On Wednesday, avalanche activity had begun to subside as only a few small (size 1) loose wet avalanche were reported that had initiated from very steep south aspect terrain at treeline elevations and below.
On Tuesday, ongoing and continued widespread large (size 2) loose wet avalanches were observed and reported by all operations within the forecast area. These avalanches were at all elevations and confined to mostly south aspect terrain with a few noted cornice collapse occurring.
On Monday, a widespread natural loose wet avalanche cycle was observed, up to 2.5, below treeline. Numerous wet loose avalanches were observed size 1-1.5 on solar aspects at alpine and treeline. Three skier triggered, size 1, windslab avalanches were reported.
On Sunday, two, natural size 3 persistent slab avalanches were observed. Both these avalanches ran to valley bottom and are suspected to have released on a weak layer of surface hoar. Two, size 1.5 persistent slab avalanches were remotely triggered by a helicopter on the same layer.
Upper snowpack continues to settle rapidly as warm temperatures have persisted. Below 1800m moist surface snow exists on all aspects, with a melt freeze crust present on south aspects that extends up to 2000 m.
At elevations treeline and below, a weak layer of surface hoar is found 20-50 cm down in sheltered terrain and continues to be reactive to skier traffic.
A second weak layer of surface hoar and/or faceted grains may be found about 60 cm deep, particularly on shaded aspects near treeline.
The lower snowpack presents as consolidated and strong.
Thursday Night
Mainly cloudy with snowfall, 1 to 5 cm of accumulation. Light northeast winds at ridgetop. Treeline temperature -3°C. Freezing levels 500 m.
Friday
Cloudy with isolated flurries, trace amounts of accumulation. Light northwest winds at ridgetop. Treeline temperature 0°C. Freezing levels 1000 m.
Saturday
Cloudy with no new precipitation. Light northwest winds at ridgetop. Treeline temperature 0°C. Freezing levels 1000 m.
Sunday
Cloudy with periods of clearing, no new precipitation. Light east winds at ridgetop. Treeline temperature 0°C. Freezing levels 1000 m.
More details can be found in the Mountain Weather Forecast.
