First, I'm sure the forecast will change many, many times. It always does when we go. Just like it does at home.
Disney is the rain, isn't always a bad thing. The parks tend to be a bit quieter when it's raining, so many people stay away or leave. Sometimes it will drop the lines down to nothing for rides-- which of course is an advantage.
Even though the rain isn't all bad-- I know an entire vacation filled w/ rain wouldn't be much fun. So here's hoping the rain keeps to a minimum for your trip!