Observation: Turnagain

Location: Sunburst

Route & General Observations

Standard uptrack to 3200′.

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)?No
Cracking (Shooting cracks)?No
Observer Comments

There were a number of small winds slabs on Seattle Ridge in many of the cross-loaded gullies. There is also a small slab observed on the west face of Magnum. All activity looks to have run during the storm.

*There were no whumpfs or shooting cracks observed today. A party we chatted with said they turned around yesterday on the Sunburst skin track just as they were reaching the ridge around 2400' due to the biggest whumpf they had ever heard. They also mentioned another party on Magnum heading towards PMS bowl yesterday also turned due to large whumpfs.

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

Broken skies
No precip
Light east winds
Temperatures in the high teens

Snow surface

Trailhead @ 900' to 1300' rain crust tapering with elevation, runnels.
1300' to 2000' soft settled snow
2000' to 3200' variable wind effect from minor wind skin to grabby breakable wind crust.


Average HS @ 900': 115cm/3.5'.

Dug 2 pits @ 2200' average HS: 140 cm/4.5'. December 1st rain crust is 45 cm down with 10 cm of slightly faceted snow above and then the 35 cm of new snow. The 12.1 rain crust is 10 cm thick. Test results: CT 22, CT 24 at the top of the rain crust. ECTX. We did dig to the ground. There were two other melt freeze crusts and some percolation columns in the snowpack. There were small basal facets in this location. However, the snowpack below the 12.1 crust is pretty dang locked up.
The 12.1 crust disappears right around 2500'. There was a hard wind layer felt probing all the way up the skin track under the softer foot of snow.

Mixed surface wind effect as noted above. No cracking along skin track.

We dug 2 pits @ 3200'. Pit #1 was 140cm (dug to ground). Pit #2 was 200 cm (did not dig to ground). New snow was slightly wind stiffened resting on the 10 cm of settled slightly faceted snow that was the surface prior to the storm. There is a very thin rime crust down 30 cm. Compression tests failed on top of this layer, CT 24, CT 22 and ECTN 22. Snow below is stiff 1F-P to until 10 cm basal facets on the ground. The facets were loose 4mm cups. When probing to the ground there is still an obvious drop in this weak basal snow.

Overall take-away the new snow appears to be bonding to the old snow surface and below 2500' the near surface faceted snow seems to be sticking to the 12.1 rain crust.

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.