Observation: Turnagain

Route
Sunburst

Weather
Warm, 39 F at 1,000’
Rain/Snow Line around 2,000’
Moderate winds out of the East
Light and showery precip, trace of accumulation above R/S line

Obvious Signs Of Instability
Recent Avalanches-NO
Shooting Cracks-NO
Collapsing-NO

Surface Obs
Rain soaked snow surface (top 2-3”) up to 2,000’. Ski penetration=6” (punchy)
Winds have moved and destroyed surface hoar that grew over the previous 3 days.
New snow/wind was just beginning this afternoon with 1-2” of damp wind blown
snow sitting on the surface.
Berries showing around the 1,000’ level-spotty in distribution (see photo)

Snow Below the Surface
We went back to a pit location that we visited 2 days ago (Feb 18) to assess
changes (2,400’ SW aspect on Sunburst ridge). Test results were similar with
scores within the same range. Fracture character was the same-Sudden planar
with columns popping into the pit (see video). The weak layer has shown signs
of strengthening, in that the hardness of the layer in the top 1cm is 4finger
(see pit profile). Compression from the weight of the slab above has helped
this. This is a fine detail in the grand scheme, as the test results tell the
real story and current situation.

We dug higher as well, around 2,700’ and found the weak layer to be disturbed in
our pit. This is a high traffic area that saw significant tracks during the
drought period when this layer was created. Test results were inconsistent in
this pit. The weak layer was reactive in 1 test, with ECTP18 SC. Slab
thickness was 65cm.

The take away from today was that the potential for avalanches to propagate
across areas large enough to produce volumes great enough to injure and bury a
person or group remains. The likelihood of triggering has gone down but consequences
remain high. New precip and wind will change the overall picture in relation to
this persistent slab problem. Rain/snow line, precip intensity, loading rates
and total load will be the key factors in determining the increase in likelihood
of triggering as well as type of avalanches (wet vs dry slab).