Observation: Turnagain

Location: Sunburst lower ridgeline

Route & General Observations

APU Snow Science 1 & 2 students field day on Sunburst common uptrack.

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

We observed collapsing and whoomphing of the thin crust within the top of the snowpack. While this was wide spread and talkative on several aspects 2200' - 2500', it was not really acting like a true red flag, since there is no real slab to trigger besides 3-5 cm of soft new snow.

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

Sunburst had some nice sunshine first thing in the morning above the valley fog, but clouds build up during the day in the field. No new precipitation during our travel day, even though the clouds were trying to produce renegade flakes here and there. Rain/snow line from overnight precipitation was low, ~ 1200'.
Air temperature remained above freezing through our tour & winds were calm.

Snow surface

Up to 1500' 1 cm of new snow & rimed particles.
1500 - 2500' up to 5 cm of new snow & rimed particles.
Thin ~2 cm meltfreeze/sun(?) crust below the new snow, but this remained supportable creating just fine ski quality. Perfect dust on crust conditions.


We dug several pits at lower Sunburst ridge. Snow depth varied 75 - 140 cm. The facet layer 25 cm from the top that was very reactive two weeks ago is still very easily identifiable, but it has been gaining significant strength and dropped its propagation propensity. These facets are getting moist! Despite significant dormancy, we were still able to get full propagation on one of the ECT tests (ECT26RP) and one PST test propagated fully (PST 45/100 end) on this old facet layer.

Photos & Video
Please upload photos below. Maximum of 5 megabytes per image. Click here for help on resizing images. If you are having trouble uploading please email images separately to staff.