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Observation: Turnagain

Location: Sunburst to 2500'

Date:
Observer:
Route & General Observations

Standard route, W aspect of Sunburst. Avalanche conditions were active with lots of collapsing, shooting cracks, one remotely triggered avalanche and a natural avalanche on Western ridge near skin track at 2500′. Did not feel it was safe to go any higher.

Avalanche Details
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Avalanche Details

Crown was filled in a little, but bed surface didn't have any new accumulation. Avalanche likely occurred near end of storm this morning.

Also a D2 avalanche on East aspect of Seattle Ridge, North of the uptrack and across the street from Eddies.

In Girdwood numerous D2 naturals reported including the SW face of Max’s released 80% of its area, with the crown extending up to the wx station. Its important to note that Girdwood received more snow than Turnagain.

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

All obvious signs of instability were observed today. There was a natural avalanche near the standard up-track on the West facing slope of Sunburst and looked like it occurred late storm. We also remotely triggered a small avalanche in a gully from pretty far away. We were 400' away when it was noticed. We also observed widespread collapsing causing shooting cracks almost every step above 2000' and looked like stretch marks in the snow.

Other red flags included:
Above freezing temps, recent precip, and recent wind loading

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

Broken skies - overcast with partial clearing mid-day and light snow around 2pm
Temps at 1000' were 34F, but could feel pockets of cooler air during day.
Winds - East 5-15 mph
Light snow falling later in the afternoon, but no notable accumulation.

Snow surface

Surface crust from recent rain/wet-snow at parking lot to about 1000'
Loose unconsolidated surface snow above, maybe 5" from overnight. It was hard to tell the interface between yesterday's new snow and what fell overnight.
In the alpine the snow was more consolidated and we could see settlement cones in the mid elevations.

Snowpack

Poor structure! Below 1700' basal facets were found on the ground with a 12" slab on top. Above 1700' well developed facets were sitting on a melt/freeze crust with a 15" slab on top. This melt/freeze crust varied in thickness from 1-6" with elevation. Most hand pits failed on isolation due to this weak faceted layer. Along the Western Sunburst ridge from 2300' - 2500' hand pits were more stubborn and revealed variable interfaces between old/new snow. In some places along the ridge new snow was sitting directly on the crust, and in other places the new snow was found on old hard layers of wind packed snow. These finding aligned with several observations from Tincan and Seattle Ridge last week where ridges had been wind affected, but just below the ridge-lines widespread facets were found in areas protected from strong NW winds from mid-November.

We dug several test pits at 2500' just below the natural avalanche on a Westerly aspect of Sunburst. Height of snow varied from 45-70cm (16"-27".) 32 degree slope angle. Test Results: ECTP7, ECTP8, ECTN11, CT11

Photos & Video
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