The rain doesn't have to be very hard for the signal to sputter in and out. Lost reception is due to raindrops sticking to the dish, which causes it to receive signals erratically. Making the dish non-stick seemed like a good idea.
There is a solution that I came across when talking to a salesperson at a major electronics store. He recommended spraying my dish with Pam or some other non-stick cooking spray.
I recommend spraying the dish every three months to keep everything non-stick.