It's supposed to be a fast moving storm so the area shouldn't have the flooding issues like TS Allison caused.
4-7 knots doesn't sound fast to me. But there appears to be nothing to the west or north (high pressure systems etc) to make it slow down or stall.
Tropical Storms often aren't a big deal, but something like Claudette, where rainfall can be measured in *yards* of rain per eight hours, will be a problem anywhere. And the flat terrain in Houston makes for more problems than other areas.
Almost all of the really destructive storms I remember growing up in Houston were tropical storms, not hurricanes. It was the tropical storms that either parked overhead for a while or kept coming back for more.