Field objective was to assess the persistent slab problem in the Banner Summit zone and how it compares to further south. There is too little data to write of the problem (two pits), but I only found weak evidence of it existing on easterly aspects and no sign of it on shadier aspects. Also, it doesn't appear that the 3/31 earthquake caused any slides to break on the early to mid-March weak layers. Still, this area continues to warrant caution—since the weak layer is down nearly 3', being wrong would be dangerous.
There was a trace of new snow on the highway this morning. The day began relatively clear, then gave way to fully schizophrenic spring weather around noon. During this short tour, I experience periods of blazing sun, full-on windy and cold conditions, greenhousing, and snow flurries. The wind increased in the early afternoon to moderate speeds, but it was not moving much snow.
I did not see any avalanche activity that didn't fit the pattern of previous observations (Haskin's photos from 4/1). Widespread avalanching occurred as a result of the 3/31 earthquake. Most of these appeared to run on a mid-storm layer and appeared to be less than the depth of the storm snow. I did not see any slides that broke into deeper weak layers.
Widespread cracking from the earthquake occurred on slopes over about 25* (see photos below). I dug down on a few of these and they appeared to go quite deep, some to the ground. Certainly deeper than the avalanche activity that occurred on slopes over about 38*.
I dug two pits looking for the persistent problem:
@8700', NE, 32*: HS 245cm. No obvious weak layer in the top 1m+ of the snowpack. The dust layer was down 90cm. No crusts were present so this should be representative of cold, shady aspects. ECTX
@8800', E, 25*: HS 235cm. Settled HST was 60cm (indicated by a faint crust below it). The dust layer was 85cm down and consisted of a matrix of thick, hard crusts. ECTX on standard loading steps, but I did get ECTP with very hard taps, breaking 85cm down on a thin layer of facets above the crust matrix.
Problem | Location | Distribution | Sensitivity | Size | Comments |
---|---|---|---|---|---|
Persistent Slab |
|
Layer Depth/Date: ~85cm |
Based on the cooler temps, clouds, and wind, the surface snow only became moist in the sheltered trees. I don't think there was a significant wet snow problem today.