Friday, September 7, 2012

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 ...


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