Unstable Surface hoar at Hebgen

Went up Hebgen with a small gaggle of folks.  In and out visibility all day, with some occasional very light snow.  Dug first pit on the subtle ridge about 15 minutes from the top of the ridge, ENE aspect, about 8700 ft.  

HS = 135 cm

SH at 105 cm

ECTP6 on the SH

No other stability test results other than a broken ECTN25 sort of mid-pack (about halfway between the SH and the old DH layer)

 

Skinned up to the ridge and when we were almost to the top my partner was out front and triggered a noticeable whumpf.  Appeared to whumpf on the SH layer.  Whumpf was somewhat localized (about 10 m in diameter as a guesstimate). The group skied a short lap in the trees while I dug a pit for the whumpf study.  Pit profile attached.  Very similar structure to first pit, but also got an ECTP on the DH layer.  ESE aspect, 8950 ft.

HS = 135

SH at 105 cm, ECTP3

DH at 45 cm, ECTP23