Isaac To Weaken Before Gaining Hurricane Strength

We are starting this off with our final track and really this track has not changed to much from what we issued and created back on the 21st of the month. The main difference is that in the short term we have pushed the track further to the north..however in the latter part we have leaned more towards the left with a Alabama/Florida Panhandle land fall. Cone of uncertainty takes it into the Western Panhandle and as far west as the SE LA region.

Isaac is generally moving towards the Northwest and this is due to a weakness that is in the ridge..However the ridge is still pretty healthy ...and what this should do is cause the system to move a little slower then what guidance was originally suggesting...
Latest Pressure was 990 MBs with winds at 70 MPH..However now we are beginning to have some land interaction.. The steering currents are below:

Also lets throw in some latest water vapor images and visible images and you can see that pretty much the island of Haiti is having an effect on the system. Remember we stressed a weaker system would be disrupted less but a stronger system has potential to be disrupted more..

Lets look at the current conditions as of 6 Z and I think this may also explain the appearance we see on visible and water vapor with not much convection on the northern side..

Now what this clearly shows you is that the northern side of the system is under about 10-20 knots of wind shear and it increases as you go to the NW towards the Eastern Gulf of Mexico as the bottom image shows (the increasing tendency) but the top image shows that it is as high as 30-40 knots to the NW of the system.  So it may have some rough sailing as it moves NW.

Convergence and Divergence is actually very good across the region. The size of Isaac is quite large so this means it will have a large reach with tropical storm winds . The weakening we anticipate because of going across land .. 
Now lets go and look at some of the guidance...

We are going to start with the GFS which is showing landfall around the Western Panhandle of Florida.

Now going to the opposite extreme and well to the left is the GGEM..

Now going back to the right end of the spectrum is the UKMET and the NOGAPS

Now we have saved the two last models for last because they are higher resolution models which would be the NAM & The European Computer Model..
The NAM is actually from the beginning of the latest guidance which is the 6 Z and this shows only 84 hrs as far as the model goes but notice that this model is NOW leaning towards the left end of the spectrum..

Now finally is the ECM and this gets it down to about 969 MBS at landfall which is in the western Panhandle..

Now one more image to look at and that is the ECM ensembles from tonights run..

Notice how the storm is slightly further west then the actual operational run? 

So what we have decided to do is to take a blend of all the model guidance because the reality of the situation is that we still have two camps and we are only about 96 hrs away from this impacting the USA.
On one side you have the Nogaps, GFS, ECM 
On the other side you have the GGEM, NAM, & ECM ensembles ...

Quite honestly I am not sure if i like the ideal of the Nogaps , ECM being on the same thought pattern with Isaac because the NOGAPS is a notoriously bad model but one thing we discovered two years ago at least in winter is if it is at the same area with a low pressure system as the other guidance..usually it means that the guidance with it is not correct.. 
We do feel that once Isaac re emerges in the GOM that significant strengthening is likely ..HOWEVER this will all be dependent on the shear relaxing in that region.

Remember the worst side of a hurricane is on the east side of the center and because of the size even if this goes a good distance off the FL coast line there will be strong gusty winds to the east into Florida and very heavy rainfall. 
If you live in any part of the region that is highlighted in the cone of uncertainty I would begin to make preparations now to protect your belongings etc. 

We will be updating this in about 24 hours once again but the track at the top is the final track less guidance follows the NAM ..