It just could be the seal in the sun roof...mine was
leaking last fall so I put duct tape on for the winter
and this last Saturday while passing traffic on the
interstate I heard this horrible noise. Pulled off
and check the car and couldn't find any thing wrong
but the noise grew louder and on the second stop
I noticed the leading edge of the tape had pulled
loose for about 4 or 5 inches and when stopped it
would lay back down. So you may have some loose
or broken seal coming out. Bill