ATL: HELENE - Post-Tropical

[Aric Dunn]

I nice convective burst on the east of the circ now where it has been very absent of convection its whole life thus far till now. clearly the circ is vigorous enough to overcome the sal/ dry air. looking at TWP there is a nice pouch of moisture associated with though.
They will probably go 40 to maybe 50 at 8pm with this new convection if it maintains.

[Aric Dunn]

Is the TUTT forecast to go anywhere in the next 3-5 days? I see that the GFS has the current TUTT dissipate in about 2 days, just as a new TUTT digs down from about 30N. Is there a chance this first TUTT moves out before it imposes doom upon 92L?

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

Notice though that TUTT pulls out and weakens just as fast as it drops down. going to be all about timing with this one.

[BigA]

Is the TUTT forecast to go anywhere in the next 3-5 days? I see that the GFS has the current TUTT dissipate in about 2 days, just as a new TUTT digs down from about 30N. Is there a chance this first TUTT moves out before it imposes doom upon 92L?

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

Notice though that TUTT pulls out and weakens just as fast as it drops down. going to be all about timing with this one.

Timing yes, but it also means that the storm would be less likely to be sheared to bits day after day. Storms can survive some shear by the TUTT; it's when the TUTT is constantly on top of them that they get blasted.

[KWT]

Notice though that TUTT pulls out and weakens just as fast as it drops down. going to be all about timing with this one.

Going to be a close call, though the models I've seen do all have a fairly marked shear zone which any system heading with any sort of westward motion from 60W onwards would have to go through if its north of 15N, which this one very likely will be.

As for track, depending on strength, I'm going for a track very close to the Caribbean islands at least till 70W, then I think a weakness is highly likely to scoop it up IF it remains a TC, if not then it'll probably just keep tolling further west.

[gatorcane]

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With the ECWMF and GFS keeping this system weak run after run (the former to a position just north of the Leewards and the latter through the Leewards into the Caribbean), I find it hard to bite on this system. There is alot of SAL around looking at the visible loops and the shear upstream from the TUTT looks pretty high. I can see the NHC raising the chance of development to 50% because the system looks to have taken on a better structure with increased convective activity today, but I think it eventually succumbs to the SAL and stable air across the MDR...I would go with 40% chance for the 8PM TWO.

[KWT]

18z GFS once again develops this around 60hrs, but looks like it forms it too far south, around 13N when it is infact close to 15N already.

[Weatherfreak000]

I'm with Wxman57....he's already too far North...seems hard to believe that he'll go so far South but after the models latest performance for the past few storms it's getting hard to go against them when such a large consensus exists he will get pushed west.

Here we go again.

[MGC]

Getting that tumbleweed look....as long as the dry air stays out of the circulation I think 92L will spin!...MGC

[gatorcane]

[KWT]

Lower level looks faster than the upper levels, not at all helpful if this system is going to have to also face shearing issues.

[KWT]

I'm with Wxman57....he's already too far North...seems hard to believe that he'll go so far South but after the models latest performance for the past few storms it's getting hard to go against them when such a large consensus exists he will get pushed west.

Here we go again.

Its already north of where the models are trying to develop it. That being said as Wxman57 said there is a decent high to its north right now so a westward track from here is probably a good bet. I personally think it may either hit the Islands or go just to the north but who knows!

[Weatherfreak000]

I'm starting to believe by examining vorticity maps that we have a very disorganized system. Circulation looks great, we have an impressive structure compared of Ernesto in his formative stages. Sadly though, strongest circulation exists further South but does this perhaps mean the circulation could hit some shear and dry air and eventually reform to the South? As usual, an unbelievable amount of uncertainty here but if he makes the Caribbean i will be worried as Ernesto cleared out the dry air.

[Portastorm]

I'm starting to believe by examining vorticity maps that we have a very disorganized system. Circulation looks great, we have an impressive structure compared of Ernesto in his formative stages. Sadly though, strongest circulation exists further South but does this perhaps mean the circulation could hit some shear and dry air and eventually reform to the South? As usual, an unbelievable amount of uncertainty here but if he makes the Caribbean i will be worried as Ernesto cleared out the dry air.

I'm curious what you're looking at, Weatherfreak000. I just went to the CIMSS site and checked out vorticity and while 92L is not very well organzied as you suggest, the vorticity maps at 500, 700, and 850 mb look fairly similar in terms of location. Perhaps I'm not looking at the right stuff.

[HurricaneMaster_PR]

Here the 18Z Tropical Surface Analysis Map



Uploaded with ImageShack.us

[floridasun78]

EURO developes 92L then undevelopes it in the Carib....at 120hr

http://raleighwx.americanwx.com/models/ ... SLP120.gif

so models are now picking up 92l their not last night that well

[Weatherfreak000]

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=


Mid Level structure appears pretty warped i'd say. Perhaps, MLC and LLC voriticty is still not aligned? I was just making a point, if the shear or dry air kills 200 mb vorticity maybe he could reform around 12N39W, which would more likely than not assist it to trek towards the Caribbean.

[Portastorm]

http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor2&zoom=&time=


Mid Level structure appears pretty warped i'd say. Perhaps, MLC and LLC voriticty is still not aligned? I was just making a point, if the shear or dry air kills 200 mb vorticity maybe he could reform around 12N39W, which would more likely than not assist it to trek towards the Caribbean.

I'd definitely concur about the mid levels being warped, per se. No, I was just trying to understand what you were looking at. That's all. No doubt a tropical low with a lack of vertical consistency has a limited future. We saw that with Ernesto until he got it all together and "stacked."

For those of you who don't know about the CIMSS site, it's a great site to see where vorticity is lined up, how winds are blowing at different levels, the status of Saharan dust, etc. Here is the main link:

http://tropic.ssec.wisc.edu/

[cycloneye]

Up to 50%

THE CIRCULATION ASSOCIATED WITH A SURFACE LOW PRESSURE SYSTEM
LOCATED ABOUT 950 MILES WEST OF THE SOUTHERN CAPE VERDE ISLANDS HAS
BECOME BETTER DEFINED OVER THE PAST SEVERAL HOURS. THUNDERSTORM
ACTIVITY IS SLOWLY BECOMING BETTER ORGANIZED...AND UPPER-LEVEL
WINDS ARE EXPECTED TO BE CONDUCIVE FOR SOME GRADUAL DEVELOPMENT OF
THIS DISTURBANCE OVER THE NEXT COUPLE OF DAYS. THIS SYSTEM HAS A
MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES WESTWARD AT 10 TO 15 MPH.

[floridasun78]

Up to 50%

THE CIRCULATION ASSOCIATED WITH A SURFACE LOW PRESSURE SYSTEM
LOCATED ABOUT 950 MILES WEST OF THE SOUTHERN CAPE VERDE ISLANDS HAS
BECOME BETTER DEFINED OVER THE PAST SEVERAL HOURS. THUNDERSTORM
ACTIVITY IS SLOWLY BECOMING BETTER ORGANIZED...AND UPPER-LEVEL
WINDS ARE EXPECTED TO BE CONDUCIVE FOR SOME GRADUAL DEVELOPMENT OF
THIS DISTURBANCE OVER THE NEXT COUPLE OF DAYS. THIS SYSTEM HAS A
MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES WESTWARD AT 10 TO 15 MPH.

ty

[cycloneye]

08/2345 UTC 14.3N 38.1W T1.0/1.0 92L