Unnerving structure in a frequent flyer

CBAC CBAC Observations

Date of Observation: 01/07/2022
Name: Zach Guy and Jack Caprio

Zone: Southeast Mountains
Route Description: Mt. Emmons, NE aspect

Observed avalanche activity: Yes
Avalanches: A couple of small wet loose slides on SW aspects NTL this afternoon.
Weather: Mostly clear, mild temps, calm winds.
Snowpack: 1 to 3 mm surface hoar growth in wind-sheltered, shady aspects, including start zones NTL.
Dug a hasty pit on belay on a slope that we know avalanched on 12/10 and again on 12/24. The structure still looks surprisingly lousy. The 12/6 depth hoar layer (3mm, fist hard) is still present: it is cohesionless and shows little evidence of rounding below a 100 cm hard slab – a concerning depth for triggering. I got propagating results after about 35 hits.
The structure caused us to change to a plan B descent route. Previous avalanche activity on that slope was not obvious to the untrained eye. The best indicator was snow depth: HS in the flats was 200 – 220 cm, and HS in the start zone was 100 cm. This observation gives me some concern for similar types of slopes such as Schuykill Ridge or Snodgrass that likely saw activity on 12/10 and again on 12/24. We dug about 10 feet below the old 12/24 crown; unsure how the structure changes further downslope.

Photos:

5221