Disorganized Leslie headed towards Bermuda

By: Dr. Jeff Masters , 4:18 PM GMT on September 03, 2012

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Tropical Storm Leslie continues to struggle with moderately high wind shear of 15 - 20 knots, due to strong upper-level winds out of the northwest. The shear is keeping heavy thunderstorms confined to the southeast quadrant of the storm. These thunderstorms are as far removed from the center as we've so far with Leslie, as seen on satellite loops. According to the latest SHIPS model forecast, the shear is expected to stay moderately high through Tuesday night, then drop to the low category, 5 - 10 knots, by Wednesday night. At that time, Leslie will be over warm ocean waters of 29°C, and the reduction in shear and warm waters should allow Leslie to intensify into at least a Category 1 hurricane by Friday, as predicted by most of the intensity forecast models. Intensification to a stronger storm may be hampered by its slow motion, which will cause Leslie to churn up cool water from the depths that will slow intensification. Once Leslie begins moving more quickly on Saturday, this effect will diminish, and Leslie could be at Category 2 strength on Saturday, as predicted by the HWRF and LGEM models. Steering currents for Leslie are expected to be weak on Tuesday - Friday, as Leslie gets stuck between two upper level lows. The latest guidance from our top computer continues to show Leslie making a very close pass by Bermuda on Saturday, and that island can expect a 3-day period of rough weather Friday through Sunday. Leslie will stay stuck in a weak steering current environment until a strong trough of low pressure approaches the U.S. East Coast on Saturday. This trough should be strong enough to pull Leslie quickly to the north on Saturday and Sunday, and Leslie may be close enough to the coast that the storm will make landfall in Canada on Monday, September 10. None of the reliable models have shown that a direct hit on New England will occur, but we can't rule that possibility out yet. The most likely long-term fate of Leslie will be for it to miss land entirely and brush by the coasts of Nova Scotia and Newfoundland, but any forecast of what a tropical cyclone might do a full seven days in advance is pretty speculative. Regardless, Leslie will bring an extended period of high waves to Bermuda, the U.S. East Coast, and Nova Scotia and Newfoundland this week. These waves will be capable of causing significant beach erosion and dangerous rip currents.


Figure 1. Morning satellite image of Tropical Storm Leslie. The low-level circulation center is fully exposed to view, thanks to strong northwest winds creating 15 - 20 knots of wind shear.

Invest 99L in the Central Atlantic
A small extratropical low pressure system that got cut off from the jet stream and is now spinning away in the Central Atlantic, near 26°N 42°W, (Invest 99L), is headed west at 10 mph, and has developed a small amount of heavy thunderstorm activity. This storm is not a threat to any land areas, and in their 8 am EDT Tropical Weather Outlook on Monday, NHC gave 99L a 30% chance of developing into a tropical cyclone by Wednesday morning.

Jeff Masters

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Quoting TropicalAnalystwx13:
I just looked at the 12z ECMWF.

My first reaction: Holy freaking crap!


Cat 5
Member Since: June 20, 2012 Posts: 0 Comments: 2169
Looks like things may pick up again in a few days,depending how far west she might manage to come before coming north.

No worries about TD 13, She looks to go poof soon enough.

Impressive looking wave off of Africa

At least we have a few things to keep an eye on............and a possibility of something surprising us?
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Model Intensity for closest approach to Bermuda:

model raw / adjusted - time

12z Euro 916mb / 911mb - 09091200
12z GFDL 960mb / 956mb - 09081800
12z HWRF 957mb / 957mb - 09081800
12z GFS 972mb / 962mb - 09090600*

avg raw: 951.25mb
avg adj: 946.5mb



* will re-do soon for 18z updates.

** fixed severe map reading error.

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Would be cool if TD 13 turns into something like this:




Hurricane Ivan (1980)
Probably one of the most impressive cat 2's.
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Quoting TropicalAnalystwx13:
I feel bad for Bermuda. They'll be in the right front quadrant of what should be a Category 2 hurricane.



um I dont like the bend to the west..
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Quoting TropicalAnalystwx13:
I feel bad for Bermuda. They'll be in the right front quadrant of what should be a Category 2 hurricane.



Or maybe 3
Member Since: June 20, 2012 Posts: 0 Comments: 2169
Analysis from the site of Mike/Frankfurt (German student of meteorology) about our mediterranean system:

Link

Mike is also on facebook.
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Quoting ncstorm:


The Associated Press is reporting it..


ok
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We need to watch this area for brief development into a tropical cyclone by the end of the week. The ECMWF, and to a certain extent, GFS, show this dropping south into the NE Gulf of Mexico and spinning up before moving into Florida.

Member Since: July 6, 2010 Posts: 113 Comments: 32802
Quoting Hurricanes101:


you sure this isn't another hoax? This week Bill Cosby, Rihanna and Eddie Murphy were all reported to have died as well


The Associated Press is reporting it..
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Quoting WeatherNerdPR:

Didn't recon investigate it that day? Because if it did, there really is no justifiable reason not to have classified it that day, since it was threatening land and was producing decent convection, and it had a closed low-level circulation. Why must you be so negative with every single storm that has formed this year?

It looked horrible most of it's lifetime.. Worse then Jose.

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Quoting ncstorm:
Michael Clarke Duncan..the actor who played John Coffey in the Green Mile has died..RIP


you sure this isn't another hoax? This week Bill Cosby, Rihanna and Eddie Murphy were all reported to have died as well
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Quoting RTSplayer:


It's utterly ridiculous that is given TD status with so high of a pressure and no previous classification. (Andrew was different).





It doesn't even fit in a mean steering layer category, so the steering maps are invalid.


Pathetic.

It's embedded in an area of high pressures. It has sufficient convection and a well defined circulation. Leave the most adorable storm ever alone.
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Good Day to all
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Quoting sar2401:


You mean the hurricane from 1932? Where did you see that this was promoted from a cat 3 to cat 4? I can't find anything about it. I can't imagine the NHC doing this.


See Storm #9 Revision


Link


"This is a Category 4 hurricane impact for Puerto Rico, which is significantly higher than the 95 kt Category 2 implied previously. Major – at least 20 kt – upward changes are thus introduced for 18Z on the 26th and 00Z on the 27th."
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Michael Clarke Duncan..the actor who played John Coffey in the Green Mile has died..RIP
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Quoting WeatherNerdPR:

How many times will I have to tell you, Helene was a named storm, as it met the criteria of one and was not the "sad clump of thunderstorms" you claim it to be.

I don't understand what you're basing your "deflate the meaning of the name" argument on. A storm is a storm, whether it's small or big, short-lived or long-tracker. So what if it was near land? If it met the criteria, either near land or in the middle of nowhere, it will be named. The name's meaning or value has always remained the same; a way to make it easier to track them. A storm isn't "very special" if it's named; many named storms are unremarkable or average.

2012 will likely be remembered as an oddball; storms behaving in bizarre ways and taking unusual paths. Of course it will also be remembered as an active season; ACE so far has been above average and, if the models are right, should stay that way because there are more storms coming.


Jeez dude I acknowledge that you're right and give in to your argument and you still nag at me? Am I not entitled to my own opinion? And when I mean a name is special I mean tropical cyclones are special for being named.

You are right though. I thought about it and I should not try and defy the choices that the NWS/NHC/SPC/etc make, and the systems this year have been legit. This year is better than 2007 though, some of those storms looked like open waves with names. I still maintain the NHC pulls fast ones with storms sometimes, and no offense but I think it's a bit ignorant to go by this 'NHC decisions are infallible' mentality.
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Quoting RTSplayer:


It's utterly ridiculous that is given TD status with so high of a pressure and no previous classification. (Andrew was different).





It doesn't even fit in a mean steering layer category, so the steering maps are invalid.


Pathetic.


Gordon was classified a TD with a higher pressure
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Leslie
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I feel bad for Bermuda. They'll be in the right front quadrant of what should be a Category 2 hurricane.

Member Since: July 6, 2010 Posts: 113 Comments: 32802
Quoting TropicalAnalystwx13:

-100C convection surrounding a perfectly symmetric eye. -.-

Don't forget the <880mb pressure.
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Quoting Tazmanian:




i think Matthew was in 2010 or 2011


oops I meant Micheal
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399. JLPR2
Quoting TropicalAnalystwx13:

-100C convection surrounding a perfectly symmetric eye. -.-


Ha! XD
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting wxgeek723:


So be it. You win. The sad clump of thunderstorms was Helene.

I just can't help but cock my head sometimes. I think tropical cyclones are very special because they are named, and I don't want the NHC to deflate the meaning of a name just because it's near land or it's for their budget or something like that.

Look I used to be a huge fanatic about this stuff. I loved watching storms be personified. 2007 was such a great year because they would name storms left and right. And since I once went through a phase like that, I can tell that the people on WU operate the same way. So of course if I come in here and say there was no need to name Kevin, Drew, and Bob, I'm obviously going to take some backlash. I just think this blog gets such a rush out of watching storms get named it sometimes...messes with their heads a bit that's all.

Besides, like I said, I want 2012 to be remembered as an odd and unique hurricane season, not a hyperactive one.

How many times will I have to tell you, Helene was a named storm, as it met the criteria of one and was not the "sad clump of thunderstorms" you claim it to be.

I don't understand what you're basing your "deflate the meaning of the name" argument on. A storm is a storm, whether it's small or big, short-lived or long-tracker. So what if it was near land? If it met the criteria, either near land or in the middle of nowhere, it will be named. The name's meaning or value has always remained the same; a way to make it easier to track them. A storm isn't "very special" if it's named; many named storms are unremarkable or average.

2012 will likely be remembered as an oddball; storms behaving in bizarre ways and taking unusual paths. Of course it will also be remembered as an active season; ACE so far has been above average and, if the models are right, should stay that way because there are more storms coming.
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Quoting JLPR2:


It's embedded in an area of high pressures, it has a tight LLC and sufficient convection.

What else does it need?

-100C convection surrounding a perfectly symmetric eye. -.-
Member Since: July 6, 2010 Posts: 113 Comments: 32802
Quoting JLPR2:


It's embedded in an area of high pressures, it has a tight LLC and sufficient convection.

What else does it need?



gorden was the same way
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Quoting Hurricanes101:


So Matthew and Nadine coming up?


Michael, not Matthew.
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Quoting Grothar:



Wow. I saw that before and didn't realize it was the remnants of Isaac. Looks potent.


That's really cool, lol. One persistent storm.



Just to keep you update on our little Medicane-Wannabe: The system doesn't look to become a cane immediately. Nevertheless it already brought torrential rains and thunderstorms to the coasts of the Mediterranean, because waters are very warm right now.

loop-link


Unfortunately I have to be very busy these days. So just a short hallo from Germany.

From the discussion on www.estofex.org (European storm forecast experiment):

At 19Z (2nd Sept.), a 568 gpdam upper low was situated just to the west of Sardinia, featuring an healthy mid/upper vortex in model data. However, buoy and surface observations show a broad and ill defined surface circulation atop the W/C-Mediterranean, with near surface streamline analysis indicating two well structured convergence zones (one west of Sardinia and the other atop the Tyrrhenian Sea). However, coastal synop data locally and temporarily support the evolution of small scale vortices, which envolve within the broad cyclonic circulation, probably spawned by local orography or regionally enhanced baroclinity (e.g. Tyrrhenian Sea). One of those vortices should evolve east of Corsica during the night hours (until my forecast starts), which however is not easy to verify due to a thick cirrus shield of an active warm conveyor belt (WCB) and missing offshore data. Forecast development however seems plausible due to a favorable placement beneath the left exit of a 50 m/s 300 hpa jet and the deep baroclinic zone nearby.

During the forecast, the main scenario of interest will be the aforementioned small-scale vortex, which is forecast to loop cyclonically over Corsica and then towards Sardinia until the evening hours along the still existing N-S aligned convergence zone. Again, some models indicate rapid organization /a profound deepening rate of the depression's central pressure, which however will be challenged for the following reasons:

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393. JLPR2
Quoting RTSplayer:


It's utterly ridiculous that is given TD status with so high of a pressure and no previous classification. (Andrew was different).





It doesn't even fit in a mean steering layer category, so the steering maps are invalid.


Pathetic.


It's embedded in an area of high pressures, it has a tight LLC and sufficient convection.

What else does it need?
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting Hurricanes101:


So Matthew and Nadine coming up?




i think Matthew was in 2010 or 2011
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Quoting trHUrrIXC5MMX:
I didn't expect TD 13 now.. wow


It's utterly ridiculous that is given TD status with so high of a pressure and no previous classification. (Andrew was different).





It doesn't even fit in a mean steering layer category, so the steering maps are invalid.


Pathetic.
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Quoting CybrTeddy:


I have noticed that they're all developing in one two punches.

Alberto, then as soon as Alberto dies - Beryl forms.
Chris, then as soon as Chris died, Debby formed.
Ernesto, then Florence.
Gordon, then Helene.
Isaac, then Joyce.
Kirk, then Leslie.


So Matthew and Nadine coming up?
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389. JLPR2
Ahh, Leslie stop stealing my wind! :\

Temp reached 90.3F in my thermometer, hadn't seen anything above 89 since I bought it.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
388. 7544
Quoting RTSplayer:



Gonna be a named TS for about 1 to 3 advisories.

Find TD 13 (no using NHC coordinates to help).




If that's a TD, then upgrade the Invest at 12N 35W immediately, please...


agree maybe 90l soon
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Quoting RTSplayer:



Gonna be a named TS for about 1 to 3 advisories.

Find TD 13 (no using NHC coordinates to help).




If that's a TD, then upgrade the Invest at 12N 35W immediately, please...

If you two think you can do better, then by all means, go get your degrees and start working at the National Hurricane Center. Until that time, stop questioning their upgrades.
Member Since: July 6, 2010 Posts: 113 Comments: 32802
Quoting TheHurricaneDundee:
has anyone else noticed this season that a strom has never been born and died by itself? there has always been another storm to acompany it for a while


I have noticed that they're all developing in one two punches.

Alberto, then as soon as Alberto dies - Beryl forms.
Chris, then as soon as Chris died, Debby formed.
Ernesto, then Florence.
Gordon, then Helene.
Isaac, then Joyce.
Kirk, then Leslie.
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Quoting RTSplayer:
There are scattered thunderstorms in Alabama which have more convection than TD13...probably stronger winds too...


but do they have a surface circulation and are they tropical?

Also you answered your own concerns in your statement...tropical systems do not have "scattered" convection
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I didn't expect TD 13 now.. wow
Member Since: April 23, 2011 Posts: 104 Comments: 14873
There are scattered thunderstorms in Alabama which have more convection than TD13...probably stronger winds too...
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Quoting Tazmanian:



no am still here if i was bannd i would not be on here right now now would i


No Taz.
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381. 7544
90L behind leslie soon imo
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Quoting Tazmanian:




99L is now TD 13

Looks like my blog prediction worked out well then, lol.
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Quoting wxgeek723:


I rest my case.



Gonna be a named TS for about 1 to 3 advisories.

Find TD 13 (no using NHC coordinates to help).




If that's a TD, then upgrade the Invest at 12N 35W immediately, please...
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so far 90L too 99L has got in RENUMBER the olny one that has not got in RENUMBER yet this year is 91L
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377. JLPR2
Last visible of TD 13


Can't see the center so I guess Leslie is improving.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting WeatherNerdPR:

Unless it's surface circulation is still intact. If so, it is the same system, and will keep its name.


My younger son said it would then be Isaac Squared.
Member Since: August 22, 2009 Posts: 0 Comments: 3167
Quoting MAweatherboy1:
I just finished up a quick blog update on the tropics if you're interested.

Link




99L is now TD 13
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3Sept.12pm's 23.5n62.2w-24.1n62.8w has been re-evaluated&altered
3Sept.06pm's 23.4n62.2w-23.7n62.8w-23.8n63.1w are now the most recent positions
(The previous vectors and straightline projections have been corrected for this mapping)
All times in GMT. Derived from NHC_ATCF data for TropicalStormLeslie at 2Sept.6pm

BDA-Bermuda :: SVN-Savannah :: SSI-St.SimonsIsland :: 4j6-St.Marys :: 1FL8-CapeCanaveral

The kinked line traces Leslie's path on its 4th day as a TropicalStorm
The easternmost dot on the longest line is TS.Leslie's most recently reported position

The longest line is a straightline projection through TS.Leslie's 2 most recent positions to an inhabited coast
2Sept.06pm: TS.Leslie had been headed for passage 178miles(286kilometres)WSWest of Bermuda
3Sept.12am: TS.Leslie had been headed for passage 3.4miles(5.4kilometres)ENEast of Bermuda
3Sept.06am: TS.Leslie had been headed for passage 301miles(485kilometres)SWest of Bermuda
3Sept.12pm: TS.Leslie had been headed for passage over St.SimonsIsland (top,SSIblob)
2Sept.06pm: TS.Leslie was heading for passage over CapeCanaveral

Copy&paste ghb-25.152n76.135w, svn-31.72n81.138w, 4j6-30.873n81.418w, ssi-31.1n81.403w, ssi-31.161n81.360w,30.896n67.435w, 32.382n64.592w, 29.2n68.478w, 32.281n64.887w-bda-32.368n64.647w, 21.3n60.9w- 22.1n61.4w- 22.8n61.6w- 23.4n62.2w- 23.7n62.8w, 23.7n62.8w-23.8n63.1w, 23.7n62.8w-1fl8 into the GreatCircleMapper for a larger map and other information
The previous mapping for comparison
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I just finished up a quick blog update on the tropics if you're interested.

Link
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Quoting WeatherNerdPR:

Exactly. Recon was there for quite some time, and they continuously found TS winds. Why do you keep denying Tropical Storm Helene's existence?


So be it. You win. The sad clump of thunderstorms was Helene.

I just can't help but cock my head sometimes. I think tropical cyclones are very special because they are named, and I don't want the NHC to deflate the meaning of a name just because it's near land or it's for their budget or something like that.

Look I used to be a huge fanatic about this stuff. I loved watching storms be personified. 2007 was such a great year because they would name storms left and right. And since I once went through a phase like that, I can tell that the people on WU operate the same way. So of course if I come in here and say there was no need to name Kevin, Drew, and Bob, I'm obviously going to take some backlash. I just think this blog gets such a rush out of watching storms get named it sometimes...messes with their heads a bit that's all.

Besides, like I said, I want 2012 to be remembered as an odd and unique hurricane season, not a hyperactive one.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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