We finally got back up to Mt Stewart, one of our usual field areas, after a long time doing our studies on Mt Troy and at Eaglecrest during the big thaw, the subsequent icy late March freeze, and the first few snowfalls after the freeze. We found some large slabs, probably dating back to the big March thaw, and a couple small soft slabs from the cycles of the last week.

The snowpack in windloaded areas had a surface slab that had some potential for sensitivity but did not react in our tests and two prominent weak layers, an upper one at 87 to 90 cm in the profile, 32 cm below the surface, composed mostly of graupel from the March 31 instability showers, and a lower one at 50 cm, 72 cm below the surface, that was the same layer of rounds over the crusts from the big thaw that produced a number of slabs on March 31.

Graupel is heavily rimed snowflakes, little pellets often misidentified as hail. (Hail is clear ice, not white balls, and is rarely if ever seen in our region.) Graupel pellets can bounce and roll downhill to accumulate in weak pockets, and are known for bonding poorly and remaining mostly unchanged in the snowpack.

We added a new test today, a cutback AK Block we are noting as "CAK". It is sized identically to the AK Block, but with a cut back side so we can evaluate the effect of the cut. The sized blocks had identical CAK5 and AK5 Q2 results on the upper layer on 41°, and our Rutschblock scored RB6 Q2 on the same layer and angle. The lower weak layer came out only on additional hard jumps on all tests, earning it a #6 Q2 for all tests.

Slope tests showed no results except cracking of the surface windcrust where its support was cut out, and the only other sign of instability was a mild thaw, mostly below 600 m. The weak layers and any windloaded spots still merit caution, but we'd mainly be watching for the next major load or thaw to reactivate the weak layers. The graupel layer in particular may be persistently weak and difficult to detect because of graupel's inherently high spatial variability.