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Observation: Hatcher Pass

Location: Gold Cord Mine - bowl E side below Pinnacle

Date:
Observer:
Route & General Observations

2 skiers were traveling NE trying to traverse to turn up valley below visible Gold Cord cable. Approached from main trailhead on E side of creek. Visibility had slowly gotten worse over the course of the day – peak flat light, ceiling had started to descend and at 5500′ or so.

Flat light prevented precise navigation, however traverse across slope appeared to be an easy approach to the mellower ramp. No whumfing or collapsing heard until above 4,000′. Then frequent small whumfs starting around 4,000 ft crossing a flat section between boulders (assumed to be from 2″ thick windslab, wind slab appears consistent with Jan 15-16). Then traversed onto short, 35 degree slope to try to attain low-angle valley under the cable. This steeper slope collapsed with large whumf when first skier was in the middle of the slope. Second skier following at safe and appropriate distance (not on same aspect, >100′ behind first skier at the time)

When skier stepped onto convexity while traversing a steeper gully, large whumf heard and cracks shot around slope 15 ft above and 20 ft laterally, skier felt slope settle. Slab did not break up or run downhill. Slope was judged to be only 100-200 feet tall but difficult to estimate given lack of mapping details and extremely flat light. Many large rocks in the area weakening the slope. Skier backed off of slab quickly and then examined crack depth and bed surface.

Slope SE facing, 35*, 4300′ elevation, crack/slab approximately 40′ wide, slab consisted of surface wind slab (2 in) gliding together with 8″ loose facets on old snow slab interface (assumed old snow from recent Gold Cord observation in forecast). Crown/crack appeared consistently 10 in. deep from limited observation. Slab slid approximately 1 inch downhill.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?Yes
Collapsing (Whumphing)?Yes
Cracking (Shooting cracks)?Yes
Observer Comments

A few small whumfs in flat terrain between large boulders prior to traversing onto steeper slope. Crack encircling slab approximately 40' wide, 15' above trigger location and 20' around either direction, limited by small gully that was being crossed.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

Temperature 13*F in Independence Mine lot, assumed around the same at time of slide. Wind around 5 mph and variable direction, no new snow, evidence of wind activity within the past few days. A few older slabs seen to fail on E and W aspects on drive in, difficult to judge age of these slides.

Snow surface

Approach conditions were variable, mix of very firm, slippery uncovered wind slab (assumed Jan 15-16 uncovered), breakable surface crust (more recent wind activity), and uncovered facets 12-18 in. deep. Slope that slid was a firmer wind crust with a light dusting of snow on top.

Snowpack

Hand pit dug at site next to crown: Wind crust and facets underneath (soft slab) failed on a harder slab - perhaps 'old snow' from more recent pit observations from this valley? Wind crust broke cleanly and facets with variable density, poor cohesion slid evenly with wind slab cover. See photo.

Photos & Video
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