From email: "Observed natural deep slab probably happened overnight with the strong winds... snowpack in the area was about 3-5’ deep mostly 4F with 20+cm of F depth hoar at the bottom... obviously not strong enough to support the wind-load." Photo: T Thorn
This large hard-slab avalanche was snowmobile-triggered on Saturday (2/20). It broke nearly 10' deep and approximately 200' across. It left large chunks of debris that piled up about 8' deep at the bottom. Photo: GNFAC
This large hard-slab avalanche was snowmobile-triggered on Saturday (2/20). It broke nearly 10' deep and approximately 200' across. Photo: GNFAC
Snowmobile-triggered avalanche occurred on Saturday (2/20) at the entrance to McAtee Basin. It broke on a 40-45 degree slope on old snow near the ground. Photo: GNFAC
Snowmobile-triggered avalanche occurred on Saturday (2/20) at the entrance to McAtee Basin breaking on old snow near the ground. Photo: GNFAC
Toured in S and E facing terrain in Specimen today. Average HS 100cm, lower 40 is FC and DH to 5mm. Observed 2 natural avalanches, both on the basal persistent layer I would guess. one maybe a week old, partially filled in (SS-N-D1R2-O), and one that ran in the last 24 hrs (SS-N-D1.5R2-O) on a SE aspect, 35 deg at 8200 ft. I thought it was interesting given the lack of new snow and seeming lack of strong winds in this area. 2/5 ECTs had propagation, we had two large collapses.
Went up the east ridge of Mount Blackmore this morning. Winds were strong in the basin and along the ridgeline from the SW. Lots of snow being transported and wind slabs forming.
Dug a pit on an SE facing, 23deg slope at 9500ft out of curiosity to see what the pit would tell me in contrast to the giant avalanche from a few days prior. Facets at the ground were about 175cm from the surface and unreactive in my CT (had a CT5 on a density change about 8" down). Switched to a deep tap and got a DT4 with a dramatic sudden collapse. Skied a few laps in the low angled trees. Had some wind slab cracking along the ridgeline but otherwise no other signs of instability.
Back side off top. Wind blown. Skied in, not sure when it broke. Continued skiing to the lower angle terrain a short distance away.
