Observation: Turnagain

Location: Sunburst and Magnum

Date:

January 4, 2021 2:00pm

Observer:

Johnston-Bloom / Wunnicke Forecaster

Route & General Observations

Standard uptrack to 2500′ on Sunburst then down and across to the Magnum NW shoulder.

Forecasted snow and winds did not verify.

As noted in many observations before, Sunburst south facing terrain and Magnum north facing terrain both have a lot of scouring from the December 22 storm and subsequent winds. This was inventoried along with other surface conditions in anticipation of the next storm.

The 12.1 crust/facet combo was a focus of the day. At this point it is a layer to track as the snow around the crust seems to be getting weaker in some areas. Will we see avalanches failing here with out next major loading event is the question?

Red Flags

Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.

Observer Comments

None observed

Weather & Snow Characteristics

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

Weather

Varied between overcast and obscured
Very light snow
Light NE winds
Temperatures in the 20°Fs

Snow surface

Trace of new snow over soft settled snow (including small surface hoar) this became a micro wind skin up to a couple inch wind crust as we traveled into more wind affected terrain. Tracks from previous day were slightly blown in on the ridge.

There is a thin melt-freeze crust to 1300' just below a few cms of soft snow.
There are some patches where the winds scoured back to 12.1 crust in the low angle terrain between Sunburst and Magnum.

Snowpack

Pit at 2350' on Sunburst west aspect, 22° slope, HS: 174 cm, the recent surface hoar and slightly faceted snow is visible just below the trace of new snow, soft slab of the top 20 cm of snow pops easily in shovel tilt on the interface with harder wind affected snow below, 12.1 crust is 90 cm down, CT 22, CT 23, DT19, DT 22, ECTX. The snow above the crust is pencil hard. The thin rain crust is stuck to slab above and the failure is in small facets below this sandwiched above a thicker layer of melt-freeze crust.
We probed around a bit a this elevation and the 12.1 crust was anywhere from 30 cm down to 130 down depending on wind loading/scouring.
Pit #2 at 2350' - See profile.

Pit #1 at 2100' on Magnum north aspect, 17° slope, HS: 100 cm, CT 8, CT 12, STVE 20 cm down on interface of slight faceted grains under a layer of wind compacted snow. 12.1 crust was 45 cm down and totally stuck in. No results with CTs and no prying apart at the layer.
Really variable snow depths and crust depths in this area as well.

Pit #2 at Magnum location HS 146cm; CT4 & CT5 on that upper layer.
VE shovel tilts.
I could see the just buried V more easily on Magnum.
basal facets stuck to ground

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