Overall all is well. The sprinklers are coming on at the correct time and WUnderground forecasts are clearly changing the watering time.
However, since the firmware upgrade to 2.1.1 I have no log entries. I tried erasing the existing log entries and they will not erase. If it matters, I have an SD card installed. The SD card does not really seem necessary but I had an old Class 4 card laying around that was so slow that it brought my Raspberry Pi media server to its knees. This seemed like a good use. Perhaps I need erase the SD card? How should I proceed to get the log working again?
P.S. Unrelated topic: I tested the Web interface on Windows 10 Prerelease. I did not expect there to be a problem and none were found.