Models Diverge - Leslie Weakening?

We are going to look at the guidance tonight first before we look at anything else that might explain what is happening with leslie. Leslie earlier yesterday afternoon finally became a hurricane a minimum Category 1 Hurricane... At times during the day yesterday it appeared as if an eye was forming.. 

Models just 24 hrs ago were essentially taking this into Nova Scotia and at one point were actually kind of close to Southern New England ..since that time...the guidance has come in further to the east and with most of the guidance now going east of Nova Scotia..

We are going to start off with the GFS ...and this is 120 hrs out which is WELL SE of its position on the 12 Z run @ 132 hours..

The GFS is much slower then the rest of the guidance is in regards to leslie and it basically moves Leslie on a NE type heading until it gets closer to Nova Scotia in which it then starts to turn more to the North and then NW and this is where we finally end up at 174 hours..

Next up is the UKMET ...

You can see that the UKMET completely misses Nova Scotia off to the east and this is actually east of 12 Z...

This is the 00z NOGAPS and if you remember this was one model showing a landfall in Nova Scotia and it now is as well to the east and other then timing differences arrives pretty much at the same spot the UKMET does and further in the frames not that far from the GFS either.. 

This gives us pause to consider that so far the UKMET/GFS are lining up with the NOGAPS and the NOGAPS is pretty much a horrible model with Tropical Cyclones...

This brings us now to the ECM or European Computer model..

Difficult to tell with 24 hour increments but this looks like it would pass just off or along the coast of Nova Scotia.. So pretty much this is slightly west of the other guidance up above...

Last but not least is the GGEM...

Looking at it from the view from Canada .. you can see that the GGEM has stayed relatively consistent with a landfall around the Nova Scotia area.

So as you can see the models are pretty well divergent tonight.. 

So now lets turn to what is presently happening with Leslie..
First the steering currents and as you will see Leslie is still with in a weak flow and there is ridging actually in the mid levels that is over top of her which is why she is moving so slow...

Now here is where we start to see some problems with Leslie . First of all lets look at the water vapor and the visible image and also the wide view water vapor..

You can still see that Leslie is pretty large in size on both the water vapor and the wide view image of the water vapor..but now we are going to call your attention to the visible in the middle and how it looks like dry air is getting entrained into the system..and lo and behold if you look at the water vapor image you will see this happening.. We took this image and point out what is happening on the image..

Now, still yet another problem is when you look at the 700 MB vorticities and we see that once again the system is NOT vertically stacked...

So its really not a surprise that we are not seeing any strengthening and according to ADT we are actually seeing some weakening..

---- Current Analysis ----- 
     Date :  06 SEP 2012    Time :   071500 UTC
      Lat :   26:17:53 N     Lon :   62:32:22 W

     
                CI# /Pressure/ Vmax
                3.6 / 989.7mb/ 57.0kt

     
             Final T#  Adj T#  Raw T# 
                3.0     2.9     2.5

 Center Temp : -19.7C    Cloud Region Temp : -42.8C

 Scene Type : CURVED BAND with 0.33 ARC in LT GRAY 
              Maximum CURVED BAND with 0.44 ARC in LT GRAY 
               at Lat:  26:53:23 N  Lon:  62:07:48 W 

 Positioning Method : FORECAST INTERPOLATION 

 Ocean Basin : ATLANTIC      
 Dvorak CI > MSLP Conversion Used : ATLANTIC  

 Tno/CI Rules : Constraint Limits : 0.7T/6hr 
                   Weakening Flag : ON    
           Rapid Dissipation Flag : FLAG  

And you can also see by the following image that the center is placed to the west of the convection and not under neath the convection..

One thing that is not a concern this evening is the shear. In fact the shear has decreased across the system and if it were to continue to move due north it would be going up an alley of lesser shear...

Presently the system is also in decent convergence and divergence as well..

So in summary what we see is mid level ridging over top of Leslie which leaves her in a weak steering flow and dry air seems to be penetrating into the system as of the time 

of this writing. This essentially means that Leslie will be slow to move to the north. And in addition to this it will continue to upwell cooler waters because of the slow north

movement. These factors all indicate that strengthening should be slower to occur. 

At this point and time with the guidance seemingly still NOT in agreement we are not going to make any changes to the track with thinking that Nova Scotia will still be the most likely place for Landfall. We do not think this will have any effect on the East Coast other then storm surge and higher tides then usual.

Intensity wise all guidance is still suggesting for this to intensify and perhaps into Major hurricane status. However ..we are going to hold off on making any type of intensity forecast because we would like to see how the slow movement will effect the systems 

development and if it can become vertically stacked and work out the dry air..

Just compare the above visible image with this one from around 11 AM and you can see the difference..

Big difference from earlier yesterday morning and tonight in the over night hours.

Stay tuned the next update will be exactly 24 hours from this one...