It looks like we have some rain on the way. I've done some thought-engineering, some research on R/C time constants, and some experimentation to see how I can integrate (in the calculus sense) the drop counting output of an RG11 to get a voltage signal with some sense of the rain rate.
What I have is a 1000 uf capacitor and a few resistors, 1k, 10k, and 100k, plus 2 AA cells for power. On the bench, I've experimented with charging the cap in fractions of a second increments similar to the 100 ms output of the RG11, and then discharging it through the same or different value resistor when the relay isn't closed.
The theory seems to be sound. Right now, I'm using a 10K charge resistor and 100k discharge and it works about as I would expect. Tomorrow I'll hook it up across the RG11 and see how it works, comparing voltages with the Davis console rain rate.
I'm not sure if I can figure out how to graph it, but I'll try.