Isaac is behaving as expected so far today. Bands of increasingly windy squalls will move across the Keys and southeast Florida through the day. The storm surge against the Keys will peak in the late afternoon when the center come over or near Key West. The tide will be near high tide then, so the water will rise in the areas that were flooded by Hurricane Georges in 1998. Perhaps not to the same level, but be ready. Heed all emergency advice.
Waves of squalls with some winds to 60 mph or more will also move over the Miami-Ft. Lauderdale metro area. The best advice is to stay inside until the storm passes.
Luckily, Isaac will only slowly organize, so no surprises in intensity are expected.
The storm surge questions remain for the west coast. The NHC has lowered their maximum estimate for southwest Florida to 4-6 feet... still extremely threatening to anyone near the water. The 3-5 foot estimate remains for areas in and around Tampa Bay. The severity of the surge in these areas will be highly dependent on timing. If the peak surge comes at high tide, it will be significant and dangerous. The question of the surge being enhanced by a shelf wave is also still open. Heed emergency advice along the west coast!
There is no obvious reason why Isaac shouldn't strengthen once it gets into the Gulf. How much it strengthens depends a bit on the exact track. If it tracks just west of the coastal shelf, the water gets very deep so that cooler water can be churned up by the storm. Over the shelf or farther off into one of the warm pools and the cooling effect won't occur. In any case, the central northern Gulf coast should be thinking about a Category 3 hurricane under the theory that you always prepare for one category higher than forecast, knowing that intensity-forecasting skill is not high.
The track spread in the models continues from last night.
See you later today on The Weather Channel.