Unfortunately, the latest Hurricane Hunter aircraft was not able to get the dropsonde instrument exactly where it needed to be. It showed a slight rise in pressure, but that seems doubtful to me as the "central dense overcast" for Isaac -- a necessary component of a hurricane -- now seems to be developing
Here is the satellite image five hours ago.
Here is the most recent. The black is much more widespread and symmetric which are both signs of better organization. Also notice that it is moving west. I'll come back to that in a moment.
If you look every closely, you might see the very first indication of an eye forming on the satellite view.
Now, let me be clear. This is not currently a major storm. But, it is starting to show signs of organization. The west movement is probably temporary and it should resume moving WNW to NW during the night.
The 11pm EDT advisory is out from the National Hurricane Center. It shows the eye of the storm moving right over New Orleans with landfall late Tuesday evening or overnight.