Donner Summit Observations

Midday snow accumulations at 2’’/hour, SW winds in the moderate range gusting strong with moderate to intense snow transport.  Dug many hand pits and ski cut lots of slopes with no signs of propagation below treeline except for some cracking around skis.  At 7600’ below treeline we dug a test pit, we had 16’’ of new snow, consistent CTE’s in the top 10’’ on large plate crystals, 2-3mm in size with clean smooth Q-1 shears.  We also had CTH’s 2’’ above the old snow/new snow interface with Q-3 shears.  ECT’s were all ECTN at this location with no propagation.  No failures occurred at the new snow/old snow interface or the Jan. 11 melt freeze crust.  Just a little higher on Wildflower Ridge another pit was dug in a high wind loaded area with 3 ½ ‘ of storm snow.  We had similar results as the other stability tests with deeper shear failure, CTE’s 18-20’’ deep on a similar large plate crystal type.  We kicked off some cornices with most not propagating, just entraining some snow and going downhill.  Some bigger loads had some shooting cracks that propagated but nothing was moving.  It felt like a slight cooling trend through the afternoon but still a very wet day out there.  Visibility was poor, never could see more than a few hundred feet away at best.

Photo#1: View up Wildflower Ridge with large cornice built out, some previous natural cornice failures rolling down slope but no slab release could be seen-debris slightly covered up by storm snow.

Photo#2: Large shooting crack from a small cornice drop from a ski kick.  N aspect, 7700’, 38 degree, wind loaded terrain.