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This station had about 17 false tips over that night of Dec 15/16, and a similar looking set of false tips the next night, after the station visit of Dec 16.
Doing a quick look back through the plots shows similar false-looking tips every night between Nov 23 and Dec 1 with the exception of the nights of Nov 27 and 28. There are a few false-looking tips during the day, but most of them are at night. Typically the tips occurred throughout the night, and were not an isolated incident which one might expect from a prankster.
I think the false tips are correlated with temperature, they seem to occur on cold nights, when the temp is below -6C.
A tip is .01 inch of precip in 5 seconds. In the example above, the ETI at station 4 is reporting every 5.04 seconds. Using a value of 5 seconds is in error by less than 1 part in 100.
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