Loaded PST on Tamarack Pk/Galena Cr

We went to the lower NE slopes of Tamarack Peak today with the specific intention of performing a loaded PST on the near surface facets below the Jan 4 rain crust. We ascended to 9,200' where wind scouring by previous NE winds became prominent. We descended NE slopes towards Galena Creek, performing numerous hand pits along the way. As we descended, our hand pits showed the Jan 4 rain crust became increasingly more prominent and the faceted snow below it increasingly weaker. We found the weakest snow down near Galena Creek on a N aspect at 8,460' and choose that as the snowpack characteristics we wanted to test.

The upper snowpack showed no failure in the compression test. Adding a 10cm think artificial slab of disaggregated snow to the surface and letting it sinter for 70 min using the methods of Birkeland et al (2018) set us up to test the faceted layer of interest. The loaded PST scored PST 10/100 end. This test result indicates that this near surface weak layer may not support rapid new snow loading from forecast storms this week.

In many near and above treeline areas on Tamarack Peak, there has been significant wind effect and scouring, breaking up the continuity of this layer. This weak layer of concern is most prominent and continuous in wind protected areas below treeline on northerly and possibly easterly aspects in this area.