Fresh wind slab avalanche seen this afternoon, possibly rider triggered.
We received a call (from a third party) about a snowmobiler that was buried with their head 5 feet below the snow and their foot sticking out of the snow. Their partners saw the foot and dug them out. The riders face was blue, but quickly became responsive after a "chest thump".
They were riding on the north side of Miller Mtn. Given the widespread winds and drifting, we suspect it was likely a wind slab avalanche similar to one spotted on Crown Butte the same day.
Total snow depth on a NE aspect was 230 cm (7.5 ft). Right side up and strong. Dust layer from Feb 4th was 70 cm deep (28 inches) with no facets under it.
Several inches of dense new snow really made great skiing and riding on top of either an ice crust or firm layer of snow from recent sun and warm temps.
Winds had moved snow at upper elevations.
Total snow depth on a NE aspect was 230 cm (7.5 ft). Right side up and strong. Dust layer from Feb 4th was 70 cm deep (28 inches) with no facets under it.
The main avalanche problem seemed to be wind slabs.
We toured out north of Bridger Bowl and onto the west side of the range, searching for shallow snow and reactive buried weak layers.
While we did find shallower, weaker snow compared to what we've seen on the east side, it is remarkably deep back there! There is close to 5 feet of snow at around 7200'. What was mainly present were layers of weak, faceted snow that formed during the high pressure at the end of January. These were capped with a slab of newer, dense snow. This slab and weak layer combo gave us ECTN's in all our snowpits. An atypical amount of snow exists in this zone, and while an avalanche breaking on this persistent weak layer is unlikely, there may be isolated areas where you may be able to trigger a small avalanche breaking at this interface.
Apart from looking for weak layers, we were nearly blown off our feet a few times by strong westerly winds. There was significant snow transport occurring at upper elevations and ridgelines. Our ski tracks and snowpit were almost entirely blown in on our return back to Bridger, and we were able to trigger cracking in small, newly-formed wind slabs. With a few more inches of snow forecasted tonight, and continued winds tomorrow, our primary concern will be wind slab avalanches breaking in the upper 1-2' of the snowpack.
Outside of wind-loaded terrain, natural and human-triggered avalanches are unlikely on non-wind-loaded slopes in the Bridgers.
