Observation: Public
Observation Details
Name:
Enji CooperObservation Date:
March 9, 2021Submitted:
March 10, 2021Zone or Region:
Snoqualmie PassActivity:
XC Skiing/SnowshoeingLocation:
Mount Washington/Change PeakTriggered Avalanches
Did you trigger any avalanches?
YesWas it intentional?
NoAvalanche Type:
Hard SlabSize:
Size 1: Relatively harmless to peopleElevation:
Aspect:
NComments:
Our group was periodically triggering 6" (mostly) up to 2' R1 wide wind slabs when walking down the ridge from Change Peak on the northeast side with our snowshoes around 10:30. All of the issues were human-triggered by our snowshoes. The wind slabs broke in a planar manner; all snow underneath was (seemingly) consolidated wind fetch or powder.Signs of Unstable Snow
None reported
Observations
Pit observations (didn't conduct ICT since I didn't have saw/trekking pole for digging out back wall and lacked time):
Approximate Location: Hill west of Mount Washington summit radio tower (47.4260, -121.7003)
* Snow depth: 195cm (from base)
* Relative pressure results:
** 182 cm from base: 4 finger interface
** 182~164 cm: non-reactive
** 164 cm: 4 finger+ interface
** 148 cm: finger interface
** 144 cm: 4 finger+ interface
** 137 cm: finger+ interface
** 125 cm: 4 finger interface
** 120 cm: finger+ interface
** 114-94 cm: finger interface
** <94 cm: unknown (didn't dig deeper)
148cm was had buried hoar snow with large crystals (likely the late February weak layer).
Media
Advanced Observations
Observed Avalanche Problem #1:
Wet LooseComments:
Saw D0.5 wet avalanche debris along Great Wall Trail, which was around 47.4356, -121.6836Wet loose debris was likely a few days old.
Later on in the day we were also triggering small localized rollerballs on sun-facing (south, east) aspects.
Observed Avalanche Problem #2:
Wind SlabComments:
* Noticed surface level slab with freshly fallen snow with pit test at Mount Washington summit.* Qualitatively observed planar slab breakage when going up and down the ridge along Change Peak.
* Noticed (and stepped on/through over the course of the traverse :D...) a large number of pillowy surfaces in leeward areas along ridge, as well as wind-textured snow.
* South aspects of the Change Peak ridge (less leeward) seemed more wind scoured than other aspects, but didn't confirm via digging.