Wet slab observed was a glide avalanche.
Observation: Summit
Location: Tenderfoot
APU Snow Science 1 toured up the standard Tenderfoot uptrack to 2500′. Temps were much cooler than expected staying around freezing on NW aspects.
Forecaster Comments
Observer Comments
We saw numerous wet loose avalanches on Seattle Ridge during drive back. Also what appeared to be a Wet Slab avalanche to the ground south of repeat offender.
Weather
Temps at the trailhead was 13 degrees Fahrenheit. Rising to 1 or 2 degrees above freezing. Calm winds and clear sky.
Snow surface
Surface conditions consisted of low density near surface facets, with surface hoar growing on top. Surface hoar was upto 10mm in size at 1600'. No melt freeze crust was found on north west aspects. Boot Penetration was 25cm. Overall high ski quality. Above tree line we found sastrugi near ridges at 2500'.
Snowpack
2438' NW aspect, 28 degree slope, HS 115, Air temp 0C. Pit had poor structure, Moderate strength with failure on the MLK BSH and on facets near the melt freeze crust near the bottom of the pit. Tests showed moderate propagation potential, no propagation during ECTs. PST 43/100 end on melt freeze crust above depth hoar, PST 27/100 SF on MLK BSH. Surface temp -10.1 Celsius, T10 -9 Celsius, T20 -7.6 Celsius.
sastrugi just above treeline @ 2500'
10mm Surface hoar @ 1600'