Observation: Gobblers

Observation Date

12/9/2019

Observer Name

Wilson, Hardesty, Grainger

Region

Salt Lake » Big Cottonwood Canyon » Mill Creek Canyon » Mill A » Butler Fork » Gobblers

Location Name or Route

Raymond Shoulder, Gobblers

Weather

Sky

Broken

Wind Speed

Calm

Snow Characteristics

New Snow Depth

New Snow Density

High

Snow Surface Conditions

Powder

Snow Characteristics Comments

Fast, smooth, good body. Could feel the crust on East-Southeast, but at 9,500' it was easily edge-able.

Summary:

Today's tour was about pertinent negatives. We traveled up Butler Fork, skied southeast and east off the Raymond shoulder, skied northwest down Gobblers and out Porter Fork, without any bulls-eye clues to instability. Here's a quick summary:

Weather contributing to instability? No. Calm winds with no current transport of the new 6-8" of graupelly snow. Despite occasional sunshine, broken to overcast sky-cover kept the snow cool (can't speak to direct south or lower elevation solars).

Instability within the new snow or at the interface? No. The 35+ degree slope off Raymond shoulder was steep enough it could have revealed meaningfully shear planes and weak interfaces, but instead the new snow was well-behaved. No sluffing, no storm-slabs at our location. Our quick CT's on upper elevation east showed resistant planar failures at the interface and within the new storm-snow, but those weaknesses did not play out.

Evidence that the new 1.5" of SWE was overloading the buried facets? No. We avoided travel in steep NE through NW slopes because the scary structure is definitely there. But even as we broke trail in lower angle north, or skirted ridges above suspect terrain, we did not have cracking, collapsing, remoting, or views of recent avalanches. Pits in upper elevation gave mixed results--and remind of us the still-present-hazard--as described below.

Snow Profile

Aspect

Northwest

Elevation

9,700'

Slope Angle

34°

Comments

Quick test-pits on East, Northwest and North-Northwest at 9,700'.

The north-aspect pits showed a poor structure, with a strengthening slab (first through 4f through finger hardness) sitting over dry facets over moist or melted-and-refrozen facets at the base. At a more wind-loaded and northerly location off Raymond the HS was 110cm and tests did not show a propensity for fracture propagation (ECTX, PST75/100 End down 70cm on facets at the top of the old snow). At a shallower (65-85cm) and more northwest location on Gobblers the failure propagated on small dry facets below a 8cm crust on 17 and 38 (non-standard, we know) taps. These results reminded us to stay clear of terrain on, below, or connected to steep slopes.

The east-aspect pit at 9700' had minimal results. A compression test had RP failures within the new snow, at the interface, and on 1.5 mm facets above the crust that capped the old snow. ECTN at the same layers. In short, this pit did not show an ability to propagate a fracture. Moreover, the most important weak-layer-- at the interface with faceted pre-thanksgiving snow--was interrupted with rocks and shrubs.

Pictures:

PST at NW 9,700'

Structure (with RP failure planes noted) on E 9,700'.