looks like this forecast only goes to the edge of the stream, so I think if you got over 20 miles out it would be much rougher than 2-4 feet and the further out you get the worse it gets. not only that but 10-15 kt forecasts have a nasty habit of turning into 20-25 kt winds -- and from the north than can turn the Stream nasty. further, its worse around Lauderdale and South because of a funnel effect caused by the closeness of the Bahamas to the Florida coast which speeds up the current.
You not only get higher waves with shorter fetch as the wind fights the current, but even worse IMO you get a really confused sea -- waves coming from all directions. Means you have to pay attention every minute to keep the seas off your bow or on your quarter depending where you're headed. It can be a really exhausting experience.
We crossed from Lauderdale to West End and had predicted light easterly winds winds suddenly increase to 15 the 25 kts and become northeast. We were half way across at the time in a relatively heavy 45-ft boat on a beautiful sunny day. It turned a relaxed sail into a really uncomfortable experience -- no fun at all. We were dog-tired when we finally got past the West End entrance markers and that was after fight the Stream for only four hours or so.
Sufficient unto the day is the evil thereof
S/V Enchantress -- Morgan 45