Consider covering any possible ingress points with this sort of stuff - it isn't really cheap, but it works instantly
https://www.masters.com.au/product/9...?bmUID=kT1eYVp. If you make a skirt join between the roof and the dome, it will be flexible enough to deal with any movement and it will certainly keep the water out.
I used similar stuff on a skylight in my daughter's apartment on key Biscayne and it withstood Hurricane Sandy. Bought some at Bunnings in Adelaide a couple of months ago, but most hardware stores will have something similar - although I have the impression that the butyl based ones have better adhesive characteristics than the pitch based ones. The butyl adheres like nothing else, but I also give it a gentle tap with a rubber mallet to make sure it has no airgaps at all.