Too bad one cannot easily integrate this to the VP2 as rainfall detector.
I did it once as an experiment. Get an anemometer transmitter, set the ID and set the console for that ID as a temp station. Make a cable for the temp/hum jack. I've forgotten the pair that are used for temp.
Connect 2 resistors in series across the temp input. Choose the values experimentally. Set the RG-11 for rainfall detection. Connect the NO relay out of the RG-11 across one of the resistors.
Now, that temp channel will show one temp reading when it's dry, and another, lower one when it's raining. According to the catalog, the extra temps update every 10 seconds, so that's pretty good resolution for "it's raining".
Any weather program that makes graphs will make a "temp" graph that shows when it was or wasn't raining, and if you do any server-side scripting, it would be easy to use the 2 temp values in any kind of display you want.
You could even set an "It's Raining" alarm in the console based on the temperature values.