Observation: Girdwood

We started the day observing DOT/ AKRR Heli-bombing mission South of Girdwood. They targeted two
specific paths (Karlsberg and Peterson Creek) between Girdwood and 20-mile (see photos below). Both
paths resulted in large avalanches failing and propagating within the basal facets. These avalanches were triggered by helicopter bombing using a moderate sized explosive charge.

There was also one natural wet slab noted this morning on Pyramid’s West face. This likely ran overnight adjacent to the slide on 1/23 (looker’s left flank). It ran full path – 3,000′ and was roughly 2-400′ wide.

The afternoon was spent hiking/ touring up to Ragged Top in the Girdwood Valley.

Ragged Top (NE facing bowl @ 2800’)

Weather:
Broken clouds, intermittent light rain and light snow above 2000’.

Obvious Signs of Instability:
Recent Avalanches: Smaller debris pile in the NE bowl looked recent (24- 48 hrs).
Large R2.5 D4 from several days to a week ago (photo below).
Several more wet avalanches in the Ragged Top and Goat Mtn. areas that have ran within the last week.
Cracking: None observed
Collapsing: None observed

Surface Observations:
Below 1900’ surface consists of crowberry, Devils Club and matted down vegetation. Once we were able
to put skins on the surface changed from very unsupportable wet melt forms to a 5cm breakable crust
above 2500’.

Snowpack Observations (@ 2800’)
Wet basal facets at the bottom of the pack are proving less reactive in snowpit tests. However, given today’s explosive triggered avalanches south of Girdwood these basal facets are showing to still be reactive with the right (or large enough) trigger. We still found evidence of the early December drizzle crust above the basal facets. The remainder of our snowpack in this location was comprised of wet melt forms with some slight density changes between fist and 1 finger hardness. Above about 2500’ we found a 5cm breakable crust capping off this very shallow (45cm or 18”) snowpack.