Not only is Gustav a hurricane, it's almost a Category 2 hurricane already! The central pressure has fallen 25mb in 24 hr, and 9mb in 12 hr. Certainly not extremely rapid intensification (yet), but fast enough to warrant concern. In microwave imagery and aircraft recon data, there is a small eye/eyewall too, but no open eye is yet apparent in visible or infrared imagery -- that could change in a few hours though. You can monitor a high-resolution visible satellite loop here:
The latest intensity (15Z) is 80kts and 981mb, with significant intensification expected over the next week. It should weaken a little bit as it passes over the southwestern peninsula of Haiti, but the ocean is so incredibly warm and deep under Gustav's predicted path (combined with little to no vertical shear), that there's no foreseeable reason that this will not be an extremely powerful hurricane in a few days.
As far as the track goes, things aren't looking good for Cuba or the US. A major hurricane landfall on the US Gulf coast looks inevitable, but this far out, it's too hard to say where along the coast.
The GFDL model's 06Z run paints an ominous picture for Lousiana and Mississippi:
This is one model and one run, and 5 days out, but a situation worth preparing for nevertheless.
Just for the record, you first heard about what's now Gustav in my August 14 update: "an impressive easterly wave has just exited the African coast and is just south of the Cape Verdes now. Several long-range models develop this into a hurricane within a week". Then again in the August 18 update: " The easterly wave I first mentioned four days ago is now near 35W and heading W at 12kts. There is a 1009mb Low embedded within the wave, and its satellite presentation is impressive. In the long term, it looks like continued W-WNW motion and gradually strengthening". Gustav has been a long time in the making.
Elsewhere, we have a couple other areas of potential development. One near 20N 56W (we've been discussing that one for a long time now), and one that recently exited Africa near the Cape Verde Islands. The first has a 1011mb Low with it and is moving WNW, and the second has a 1008mb Low and moving WSW at 10kt. The next names on the list are Hanna and Ike. Ike replaces Category 3 Isidore (2002) that caused so much destruction on the northern Yucatan Peninsula, and then moved straight north into New Orleans as a tropical storm.
Please visit my tropical Atlantic headquarters.