We toured in the Southern Whitefish Range to try and get a better idea of the distribution of the recently buried surface hoar. The specific surface hoar layer we were hunting for is a layer that is found throughout the Swan and Flathead Ranges.
We dug several pits on SE, SW, and N aspects and were unable to find any recently buried surface hoar. We did find a rime crust about 3” under new snow, and the New Years crust further down. We did not get any propagating results on these layers.
We did notice slightly rimed surface hoar growing on the current snow surface on all aspects at mid and upper elevation. Most of the grains were 5-10 mm.
We observed no obvious signs of instability. No cracking, collapsing, or recent avalanches.
We saw the remnants of a rollerball cycle in steep, open, south facing terrain that occurred a few days ago.
On a NNE aspect at about 6400’ we dug 2 deeper pits to look at persistent weak layers further down in the snowpack. Here we found the sleeping dragons. The first pit was unintentionally dug on a slope that had previously slid. In an extended column test, we had a propagating result with moderate force on the early November crust buried at the base of the snowpack. The second pit, which was 50 yards away on the same slope, did not produce a propagating result with the standard 30 taps. However, after two more good hits, it broke cleanly on a layer of well-preserved surface hoar down 110 cm. Both of these layers produced large avalanches in the previous weeks. Although they are proving to be mostly stubborn to unreactive at the moment, a large loading event could wake them back up.
