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Observation: Turnagain

Location: Sunburst

Date:
Observer:
Route & General Observations

Toured to 2450′ on the West ridge of Sunburst. Snowing and blowing hard, visibility was down to a couple of feet at times, and the strongest gusts were knocking us off our feet. Objectives were to inventory surface conditions and to see how intact and continuous persistent weak layers are on aspects that were windward during last weeks wind events.

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?No
Collapsing (Whumphing)?Yes
Cracking (Shooting cracks)?No
Observer Comments

Extremely small and subtle collapses were felt in places that felt notably punchy and upside down when pole probing.

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

Snowing ~1"/hour, ~3" of new snow at 2 pm. Winds moderate gusting to strong and extreme, channeling from the NE at the road, and from the E above treeline. 29 degrees at the road. Ridgetop temps in the teens, winds easterly 50 mph gusting 70+ mph. (96 mph at 6 pm!)

Snow surface

~3" of new snow sitting on 2-3" of 0.5mm near surface facets. New snow at the road was moist.

Snowpack

Hand pits and pole probing showed a 6" to 1' wind slab sitting over near surface facets above treeline. We dug 3 pits around 2400', on the West shoulder of Sunburst. Height of snow averaged ~170 cm, though on the windward NW ridge HS varied from 90cm to 150cm, and was as shallow as 40cm in places in places where winds had blown the surface down to old melt-freeze crusts.

Pit 1: 2450', NNW, 24 degree slope. CTV, CT4, ECTN12 down 15cm on facets below wind slab. CT16, CT28 failed down 75cm on facets between two melt freeze crusts.

Pit 2: 2425', NW, 18 degree slope, HS=133 cm. Test Depth=85 cm. CT12 SC, CT27 BRK, and ECTN25 down 27 cm on 6mm Jan. 21 BSH and predominantly 1.5mm facets. The rain crust / facet layers were 43 cm down in the pit but not reactive in tests.

Pit 3: 2400', W, 20 degree slope, HS=170 cm. Test depth=100 cm. Found January 21 BSH & facets down 30 cm below a 1F hard wind slab and facets above a melt/freeze crust down 45 cm below a K hard slab. CTN, ECTX on both layers, but the facet-m/f crust layer popped out very easily in shovel shears. Able to remove my entire column in one cohesive piece.

Photos & Video
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