Bridger Range

On Jan 5 we saw this ~150' wide, 1'deep storm slab in Truman Gulch. GNFAC

On Jan 5 With decent visibility we drove up Bridger canyon to Battle Ridge to look for recent avalanches. The most noteworthy was a slab 500'+ wide, 2'+ deep in Argentina Bowl (photo), 1 day old probably. Photo: GNFAC

With decent visibility we drove up Bridger canyon to Battle Ridge to look for recent avalanches. The most noteworthy was a slab 500'+ wide, 2'+ deep in Argentina Bowl (photo), and there was an R1-R2 sized debris pile below the Saddle Peak cliffs, but clouds obscured the top of Saddle. There were a few short, small wind slabs that broke along the ridgeline north of Bridger Peak. We also saw a 150' wide storm slab in Truman Gulch (photo).

We looked at the snowpack on the west side of the range in Truman Gulch. In four snowpits HS was 70cm (W, 8200'), 112cm (SW, 8400'), 135cm (NW, 8000') and 140cm (W, 8500'). The two deepest pits had ECTP28 on facets (2mm) 40cm above the ground. The other two had poor structure and soft weak snow in the bottom 30-40cm, but did not propagate in tests. Overall, the snow structure is poor and not trustworthy on the west side of the Bridgers. With more loading we could see big avalanches, whether it's this week, later this month or later in the season, and currently it seems possible a person could trigger a persistent slab avalanche here.

On the ramp there was evidence of yesterday's wind in the form of wind slabs that broke and their debris subsequently drifted over. Today wind was calm to light, and there is plenty of snow to transport if the winds do pick up. A few hours of moderate wind could easily form fresh wind slabs. Snow was starting to fall lightly in the late afternoon.

Toured up the ramp this morning, found between 3-6” of new snow on the skin track, winds were fairly strong from the north/northwest and moving snow. Snow was falling heavily for the duration of the tour. As we made our last switchback in the ridge line meadow (8500ft directly east facing) near the top of the ramp, we triggered a wind slab. It propagated about 200 ft wide and was 3 ft at the deepest point. Interestingly on the edges and near the bottom (downhill side) of the slab it was only a few inches deep. It broke on the interface between the wind loaded snow and the light and dry snow we received a few days ago. When we entered the upper meadow there was no evidence of tracks from the day before. Further down the ramp we found cross loaded rolls that produced shooting cracks and collapses, and active snow loading from new snow and wind. A half hour later on our ski down, the skin track was partially buried by new snow as we exited the area.

Photo: H Meyers 

Photo: H Meyers

Saw a small recent looking storm slab avalanche that appeared to be naturally triggered above the road on a south facing slope around 6000'.  It ran all the way across the slope ~30' wide and  ~4" deep within the recent snow.  The snow didn't move far enough to reach the road.  The slope was quite steep-- we didn't measure but I'd estimate 40*.

Photo: H Meyers