Firstly, I don't know where DD gets his rainfall figures but BOM reports: Rain since 9 am today was 0.0mm. As of right now the track is rated Good 3.
The forecast is for showers Friday & Sat with possibility of storm Friday. That rain may OR may not fall at Bundall, so nobody knows what the rating will be on the day. fate will determine that.
I suggest you play the odds and assume the track will be good or dead at worst.
Are you going to tell us the name of the noble steed? If you can, I am happy to rate the race for you.