Observations from Mt. Tallac

Minimal signs of slab instability observed on Mt. Tallac this morning though early afternoon. Loose dry instability was common in areas steeper than 37 degrees. Ridgetop winds were not as strong as forecast and ongoing wind transport was minimal. Winds were generally light on the peak with moderate speed west winds limited to ridgetops. Wind slabs were present in near and above treeline areas (4F+ hard over F to 4F- hard), but tests indicated that they were well bonded to the old snow surface. This was despite the presence of a graupel layer at the base of the recent storm snow below the wind slab. Test pits dug on a NE aspect at treeline at 9,260' (38.911354, -120.101737) and on an E aspect at treeline at 9,300' (38.912658, -120.102349) showed no additional signs of instability. Signs of slab avalanche activity visible on peaks further west into Desolation Wilderness were small and very isolated.

Gradual warming conditions were occurring between sun breaks. Snow was not falling off of or melting off of trees as of 1 pm even down at 6,500'. A few small areas of roller balls were noted off of the  SE aspect cliffs in the main east bowl (Tallac Cr. drainage), but were very isolated activity.

Photo#1:  Small natural wind slab avalanche off of ridge behind Mt. Tallac.  North aspect, 9200', partially covered by storm snow.

Photo#2:  Skier triggered loose dry avalanche (sluff) on steep E aspect below treeline (noted lat/long).

Photo#3:  Repeatable ECTN's showed that propagation was not likely on wind slabs at this location.  CT's did not show clean shears. Graupel layer was noted near the base of the recent storm snow but was not reactive.