Route & General Observations
Toured up standard Tincan up-track to a high point of 2800′. Observing how widespread the distribution and reactivity of the MLK Jr Day (1/21) buried surface hoar was with the overnight 4″-10″ of new precipitation.
Obvious signs of instability
|Recent Avalanches?||Yes||Collapsing (Whumphing)?||No||Cracking (Shooting cracks)?||No|
No observed recent avalanches on Tincan.
Saw four natural D1.5 - D2 storm slab avalanches on the South end of Seattle Ridge near Bertha Creek and one natural just South of the uptrack. See photos below.
Upper 20s - Low 30s (F)
Very Light Snow (S-1)
Calm - Light Winds
Road to ~1500' - 4"to 6" new moist snow with drier grains directly under the surface
~1500 - snow surface transitions to dry grains
~2800 - new snow depth increases gradually to approx. 10" at our high point
The MLK Jr Day (1/21) BSH layer was still found wide spread at multiple elevation bands. We saw it in multiple hand pits and test pits on different wind effected aspects within the same elevation band.
Beginning at 1800' we lost the obvious storm/rain crust interface and found the MLK Jr /Melt Freeze interface.
At 2000' - we were able to find that MLK Jr BSH (7-10mm) buried approx 14" down and shear with moderate force in a planar fashion on top of a MF interface. We also found a mid-storm crust interface approx 10" down which did not shear.
At 2300' - we found a very thin eggshell melt freeze / near surface facet crust interface (NSF/MF/DF .5mm) above the MLK Jr BSH buried approx 18" down and shear with moderate force in a planar fashion. The hand shears were failing on the MF/NSF interface, not within the BSH.
At 2800' - the MLK Jr BSH was a very obvious line buried approx. 8" and 24" down in the snowpack depending the amount of wind loading the test area possessed and showed some propagation propensity in multiple stability tests. The 1/11 BSH was noted approx 4" below the MLK Jr BSH in both locations. The Xmas BSH was found 20"and 42" down depending on the pit location. Neither of these BSH could be seen in the pit wall, and only showed results in one stability test.
Tincan Windward Test Pit - 2800' - W. Aspect - HS:171cm - 11* slope
CT7/CT14 down 20cm on MLK Jr BSH (8-10mm)
CT9 down 30cm on the 1/11 BSH (3mm)
ECTN14/ECTN15 down 20cm on MLK Jr BSH (8-10mm)
PST60/100 (END) down 20cm on MLK Jr BSH (8-10mm)
PST50/100 (Arr) down 20cm on MLK Jr BSH (8-10mm)
*No results on the Xmas BSH (3mm) that was 50cm below surface
Tincan Leeward Test Pit - 2800' - NW Aspect - HS:275cm - 27* slope - Airtemp: -1.3 c
SSH down 60cm on MLK Jr BSH (8-10mm)
CT20 down 60cm on MLK Jr BSH (8-10mm)
ECTX x 2
PST30/100 (END) down 60cm on MLK Jr BSH (8-10mm)