Hurricane Leslie Update Including New Revised Track

We have shifted the track east but not as far east as some of the guidance is suggesting on tonights model runs. For those in Nova Scotia please keep in mind that even though the center is not expected to make landfall in Nova Scotia you will still have strong gusty winds to tropical storm force to contend with. We also would like to note that the track is not set in stone yet either. So we will continue to watch and monitor the situation.

The Hurricane has not gotten its act together over the last 36 hours . There is some reasons for this:
1: With the storm being stationary what this is doing is causing colder waters to upwell so that now Leslie is remaining stationary over colder waters which limits the intensity and perhaps will cause the system to weaken.
2. As water vapor images will show ..Leslie is still having a battle with dry air..

These images clearly show dry air is effecting the system. Again this is something that you do not want to see happen or occur in a developing Cyclone..

3. Shear is essentially anywhere from 5 knots to 20 knots across the system ..However ..a path north thru less shear and higher shear east and west ..could allow this to strengthen once it moves away from the colder water.

And you can see the clear stretch it would move thru if it moves on a direct north passage.

Convergence and Divergence we notice is still decent across the system but there is still one more problem that Leslie faces and this has been an issue from day 1 and that we are still not dealing with a vertically stacked system..

So in summary we still have some issues that need to be rectified with Leslie...
A . The upwelling of coolers ..this could potentially weaken the system.
B Dry air is still getting entrained into the system
C. Shear is still between 3 and 20 knots...

So what is the guidance suggesting is going to happen with Leslie..? Virtually all guidance has come east from a Nova Scotia Landfall.. We are going to post the GFS/GGEM/ECM the three main global models..

Now finally we come to the point of looking at the steering currents ..

Steering currents continue to show that Leslie remains in a weak to almost Non Existent flow. This is mainly due to a ridge that is to her north. In order for this to start moving due North this ridge is going to have to move off to the east. 
You can tell by the ADT center relocation image that Leslie has barely moved..

You can see the movie here at this LINK

Now the thing we have to watch is for any weakening if any weakening does indeed occur this could cause Leslie to stay more or less trapped under that ridge and remain stationary longer. The path off to the NE is very determined by a trough that will be moving off the east coast in about 72hrs. The thing is that if Leslie DOES NOT start moving soon..there is a chance that she could miss that trough then and we would be talking a completely different scenario.
As is we do not think there will be any further intensification until Leslie moves away from the colder waters. 
By the time Leslie gets to the Newfoundland and Novia Scotia it should no longer be Tropical but rather extratropical.
Stay tuned we will have an updated outlook in 24 hrs ...

September 7th Severe Weather Outlook

We have not done a severe weather outlook for some time because the Tropical Storms take predominance over the severe weather. However..I know many people on this page (storm support ) have fears of storms so even if i do not do an outlook you are still able to message me and I will answer any concerns you may have.. I also have made my phone # available to those on this page..Some have taken advantage of having the number and using it while others still have not.. 
For those that are reading this on the Real Wx Services page the above was addressed to those on my other page that I admin called Storm Support & Severe Weather Education.
Now back to the severe weather outlook .
Temperatures today across the area where there is the potential of severe are goin

g to be in the 80s to the 90s.
http://www.twisterdata.com/data/models/nam/221/maps/2012/09/06/18/NAM_221_2012090618_F30_TMPF_2_M_ABOVE_GROUND.png
Dew points will be in the upper 50s to upper 60s depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/09/06/18/NAM_221_2012090618_F30_DPTF_2_M_ABOVE_GROUND.png
CAPE or Convective Available potential energy will be anywhere from 500- to as much as 4000 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/09/06/18/NAM_221_2012090618_F24_CAPE_SURFACE.png
Lift Index
Lift in the atmosphere will generally be from 0 to negative 10 however there is isolated locales that are around -11 to -12
http://www.twisterdata.com/data/models/nam/221/maps/2012/09/06/18/NAM_221_2012090618_F24_PLI_30_0_MB_ABOVE_GROUND.png

Now when it comes to tornados we like to look at things like the Energy Helicity Index and the Helicity and the Shear...
When we see the EHI like it is across Indiana /Illinois this tells us that tornado potential is possible especially in that part of the area.
http://www.twisterdata.com/data/models/nam/221/maps/2012/09/06/18/NAM_221_2012090618_F24_EHI_3000_M.png

And you will see that it is in these general areas that the Helicity is also on the high side...
http://www.twisterdata.com/data/models/nam/221/maps/2012/09/06/18/NAM_221_2012090618_F30_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png

Shear also is pretty substantial incoming with this cold front..
http://www.twisterdata.com/data/models/nam/221/maps/2012/09/06/18/NAM_221_2012090618_F30_SHRM_500_MB.png

Shear shows to be 30 to as much as 60 knots...

At the surface we have a cold front that will be dropping east and south east across the region and this will serve as the trigger for the the severe weather potential.
http://www.hpc.ncep.noaa.gov/basicwx/95fwbgus.gif
Outside of the regions mentioned above for the tornado potential the main threats will be winds and hail...

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...

Leslie Still In No Hurry To move..

We are starting with a look at ADT and where the center is located for Tropical Storm Leslie. According to ADT : 25:20:04 N Lon : 62:51:28 W . It seems as if the center is trying to contract more and move under neath the heavier convection. If you look at the movement focusing on the center 
Center Movement! 

You can see that the movement has been relatively stationary.  The next thing we take notice to is the pressure is dropping and is now down to 992 mbs. However..it appears as if the winds are not yet catching up to the pressure dropping.

Next thing that one has to take notice to is the extremely large size of Tropical Storm Leslie. This is one contributing factor as to why this has not become a hurricane yet. Another contributing factor which the models I do not believe take into consideration is the fact that since this has been stationary for quite some time now it is causing cooler waters to upwell which also will slow down the intensification process.
Still yet another reason that we have not really seen Leslie become a hurricane yet is because the shear is kind of high across the system from 10-30 knots...

The good news is that the shear is starting to decrease. Once this shear decreases it should be easier for Tropical Storm Leslie to become better organized. 
Another factor is the system has still yet to become vertically stacked as the 200, 500, 700 mb levels show.

And for the first time since we been tracking this system it is no longer in the best convergence and divergence. 

Those areas are mainly to the south of the system or in the case of the bottom image over the southern part of Leslie.

Steering currents suggest very weak flow ..However a slow Northwest ward movement is occurring. But as we mentioned the system is not in a hurry ..as it has only been moving or jogging about .2 N and .2 W so about 2 MPH..

Guidance is starting to come into better agreement ..However we still have some timing issues and in addition to timing issues ..it would appear that the GFS is the right side outlier. Majority of your guidance is pointing towards a Nova Scotia landfall..

This is the GGEM which gets the system down to about 956 mbs and makes landfall in Nova Scotia. 

As you can see this is the 00z NOGAPS and it is slightly west of the GGEM but it still has the general theme with landfall in Nova Scotia..

This is the 00z ECM and it appears somewhat west again of the 12 Z ECM and is really more consistent with its prior two runs before the 12 Z run yesterday and this would appear to take Leslie into Nova Scotia as well..

Then we have the GFS which comes close to Nova Scotia but never makes any actual landfall..

We sincerely feel that the GFS would be an outlier to the east ..and is to far to the east. Just in is some better pictures of the ECM..

As we stated earlier yesterday when we received a comment about it should be now safe to say that SNE is out of the game for Leslie that with guidance still showing as close as what it is showing and still being 5-6 days away it is never safe to "assume" anything.
The ultimate track is all going to depend on how strong the ridge is able to build to the north and east of Leslie. If the ridge ends up being stronger then expected then a more western track can be anticipated. 
We have no change in our thinking with the track from over night last night with the landfall being in Nova Scotia..However..since the guidance does get kind of close to southern New England and the fact that Leslie will only grow in size this means that the wind shield will also grow in size.
Also earlier in the evening NHC mentioned a jog to the west..If this occurs more frequently this would also help with bringing this system closer to the east coast. So things still need to be monitored and we will update this in another 24 hrs...