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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.
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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