Gaston still a threat to redevelop

By: Dr. Jeff Masters , 3:17 PM GMT on September 05, 2010

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For the first time since August 22, when Danielle became a tropical storm, there are no named storms active in the Atlantic. An extratropical storm absorbed Tropical Storm Earl last night, bringing an end to the 11-day life of the 2010 season's longest-lived storm. While Earl was mostly a non-event for North Carolina and New England, the storm gave Nova Scotia a solid pounding, reminding us of what could have easily happened to New England had the forecast track deviated slightly to the left. Kudos go to the computer models and NHC, who successfully predicted the path of Earl very accurately four days in advance. As we approach the climatological peak of Atlantic hurricane season, which occurs on September 10, there are no indications that today's break in the action represents a beginning of an extended quiet period in the Atlantic. Indeed, we have two systems that could become tropical depressions in the next day, and we also have model predictions of another storm to come late in the week.


Figure 1. Morning satellite image of the remains of Gaston, approaching the Lesser Antilles Islands.

Gaston near tropical depression status again
The remains of Tropical Storm Gaston, located about 700 miles east of the Lesser Antilles Islands and moving west at about 13 mph, are close to reaching tropical depression status again. Recent satellite imagery shows that Gaston's remains have developed a well-organized surface circulation, but not enough heavy thunderstorm activity to be considered a tropical depression. A large amount of dry air surrounds Gaston's remains on all sides, as seen on water vapor satellite loops. This dry air will continue to be a major impediment to development. The latest SHIPS model forecast predicts shear will remain moderate, 10 - 15 knots, for the next three days, then fall to the low range. The winds creating the shear are coming from the east, where a tongue of dry air has intruded. These easterly winds will be able to drive the dry air into Gaston's core, disrupting it, unless the storm can find a moister environment, or moisten its environment on its own by generating enough heavy thunderstorms. Gaston has managed to develop more heavy thunderstorms near its center of circulation late this morning, but the amount of dry air it is battling is formidable. Even if Gaston does manage to become a tropical depression today, development will be slow over the next few days, due to the dry air. When Gaston passes over or just to the northeast of the Lesser Antilles Islands early Tuesday morning, the storm is unlikely to have more than 50 mph winds. More significant development is possible later in the week, as the atmosphere should be moister for Gaston. Gaston may threaten Puerto Rico on Wednesday, the Dominican Republic on Thursday, and Haiti, Jamaica, and/or the Turks and Caicos Islands by Friday, depending upon the storm's interaction with a trough of low pressure expected to move off the U.S. East Coast later this week. The earlier Gaston develops into a tropical storm, the more likely it is to "feel" the upper-level winds of the approaching trough, and curve more to the northwest. The HWRF model predicts Gaston will develop by Monday, and pass just northeast of the Lesser Antilles Islands Tuesday morning. The GFDL model, on the other hand, delays development until Wednesday, keeping Gaston in the Caribbean. The GFDL has Gaston hitting Jamaica as a strong tropical storm on Friday morning. However, the GFDL forecast is dubious, because on Wednesday and Thursday, Gaston may have an encounter with the high mountains of the island shared by the Dominican Republic and Haiti, Hispaniola, which could easily destroy a system as fragile as Gaston. Gaston has a 70% chance of developing into a tropical depression by Tuesday, according to NHC.

Gulf of Mexico disturbance 90L
A concentrated area of heavy thunderstorms (90L) has developed over the extreme southwestern Gulf of Mexico, in the Bay of Campeche. Satellite imagery shows that this disturbance is disorganized, but has some modest spin to it. The disturbance is under a moderate 10 - 15 knots of wind shear, and has a 60% chance of developing into a tropical depression by Tuesday, according to NHC. The disturbance is headed northwest at 5 - 10 mph, and should bring heavy rains to the Texas/Mexico border region on Monday, according to the latest run of the GFS model. The main impediment to development will be the limited time 90L has over water; the storm will be ashore by Tuesday, which doesn't give it much time to develop.

Elsewhere in the tropics
The GFS and NOGAPS models are predicting development on Thursday of a tropical wave that will emerge from the coast of Africa on Tuesday or Wednesday.

Next post
I'll have an update Monday morning.

Jeff Masters

Sunrise Surf was cranking (RIWXPhoto)
Sunrise Surf was cranking
Post Hurricane Earl surf photos at Newport, RI (RIWXPhoto)
Post Hurricane Earl surf photos at Newport, RI

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1785. P451

Quoting KoritheMan:


Well, the system did have convection, but it was well-removed from the center. So... perhaps subtropical?


I don't believe so.

And this year is a new term "Post-Tropical"

I mean, come'on. It's either tropical or it's not.

Many systems emulate tropical characteristics on satellite but they simply are not.

Living in NJ I can tell you many a potent Nor'Easter suddenly has an eye.... but... it's not tropical, nor extra-tropical... nor post-tropical. It's just a very intense cold core low pressure system.

There is a difference.

The only non-tropical-basin systems that can potentially be classified as Tropical systems are those in the Mediterranean sea.

Those come close. And maybe a few did make it.

But that's it. These other systems are just an enigma. They wrap up, form "eyes" but they just are not tropical.

They aren't Tropical Storms or Hurricanes. They're just very intense lows that may mimic them to a degree. But they still lack your CDO. Therein lies the difference.

Again, weather isn't solely based on the surface temperature.... but more on the DIFFERENCE of temperature from surface to upper levels. The difference gives you the weather.

That's why you can get thunderstorms in the midst of a 20F snowstorm. 20F surface, -100F upper level? Thunderstorm. 80F surface, -20F upper level? Thunderstorm.

However, with TROPICAL systems there is more to it than that.... and you just don't have it in these instances, sans, the Mediterranean systems.

I think they are akin to your NE Atlantic systems that so many say "Oh, come'on, it's over 20C waters, no way is that tropical!" when, indeed, it is.

Grace comes to mind.

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Quoting TexasHurricane:


Hi AtHome.... :)


Hey Tex. :)
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Quoting KoritheMan:


Well, the system did have convection, but it was well-removed from the center. So... perhaps subtropical?


A tropical cyclone has a warm core sturucture sustained by convection. However, deeply-occluded extratrpoical cyclones can have convection and even a low-level warm core, but its not a tropical cycloen folks unless it has a fully developed vertical warm core with anticyclonic outflow.

To see the differences between extratropical, subtropical, and fully tropical, again I refer to Figure 4 of this blog post.
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1782. leo305
Quoting hurristat:
I have a question for all y'all -- is this a tropical system or not?

Link


cold core, means it's mostly extratropical..

but I guess it's a sub tropical low since they classified it as a hurricane or did they?
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Quoting P451:


Last year I posted a storm located just off the coast of Antarctica that had a warm core and was wrapped up tightly. However, it was NOT a tropical cyclone. It was devoid of heavy convection. As is this system that has been posted.

There are criteria to be met and these systems just don't meet them.



Well, the system did have convection, but it was well-removed from the center. So... perhaps subtropical?
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1780. centex
Quoting Grecojdw:


At the absolute highest barely a hurricane if there is an episode of RI (rapid intensification).
The amount of rain has little to do with wind speed. Some TD/TS have caused major flooding events. Fortunately this one does not look to be setting up stall Central Texas or points south so should not be an extreme event but still could get bad in some areas; don't think they can predict too well where the flooding rain will setup.
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Quoting mtyweatherfan90:


Then that would the first "tropical cyclone" to form over a lake? Just curious. :)


If it was verified, yes.
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Quoting hurristat:
I have a question for all y'all -- is this a tropical system or not?

Link


No, I don't think it was. See Figure 4 of this blog post. I think this Huron cyclone ultimately never made it past the deep-occlusion stage of Figure 4.

...Although that article says the Huron cyclone got passed its baroclinic stage and was still intensifying perhaps due to heat fluxes, perhaps it was a weak subtropical cyclone? There was also a similar system like this in the Meditterrranean Sea in 1995.
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1777. P451
Quoting KoritheMan:


If I'm not wrong, it did have an upper-level warm core, so it could have briefly been tropical.


Last year I posted a storm located just off the coast of Antarctica that had a warm core and was wrapped up tightly. However, it was NOT a tropical cyclone. It was devoid of heavy convection. As is this system that has been posted.

There are criteria to be met and these systems just don't meet them.

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Quoting KoritheMan:


If I'm not wrong, it did have an upper-level warm core, so it could have briefly been tropical.


Then that would the first "tropical cyclone" to form over a lake? Just curious. :)
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1775. P451
Quoting hurristat:
I have a question for all y'all -- is this a tropical system or not?

Link


Where is the convection?

I posted an image last year of a James Bay low that was incredibly cut off and looked like a tropical system just like that Huron low... but it had no CONVECTION.

Not...Tropical.

Looks neat, looks close, but it just is not.


The closest thing to a non-ocean-basin tropical system are your Mediterranean systems. A few might have absolutely made the cut. Except for temperatures. However, what is temperature? It is relative. If you're in 10C waters and you have 10C temps 50K up in the atmosphere is it not a "warm core" system? And if it's a closed low with an eye and convection around it. Is it not a tropical cyclone? I believe it is!

Research the Mediterranean tropical cyclones. I think the few that existed are in reality... Hurricanes.

However, what you posted, is not.
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Quoting hurristat:
I have a question for all y'all -- is this a tropical system or not?

Link


If I'm not wrong, it did have an upper-level warm core, so it could have briefly been tropical.
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1773. Patrap

GOES-12 Atmospheric Imagery




These images are primarily for use in tropical storm monitoring. There are several areas to choose from providing a large-scale view of the Atlantic, down to the Gulf of Mexico. During hurricane season, the hurricanes page provides a variety of GOES atmospheric products to help monitor the active storms.
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1772. centex
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I have a question for all y'all -- is this a tropical system or not?

Link
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1770. P451
Good EVENING, Ladies and Germs.

Was a beautiful Sunday here in NJ topping out at a dry 82F, now 55, looking towards 48-52 for a low.

That aside,

Here is TD10: 12 Hour WV Loop:

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Quoting cccidojr1:
yesterday our local abc weatherguy said this LOW wont effect us at all. now the station is saying localized areas could get up to 10 inches.. how strong do u guys think this system will get?


At the absolute highest barely a hurricane if there is an episode of RI (rapid intensification).
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Quoting cccidojr1:
yesterday our local abc weatherguy said this LOW wont effect us at all. now the station is saying localized areas could get up to 10 inches.. how strong do u guys think this system will get?


60 mph. I don't currently expect that, but that's the highest I could see it reaching, wind wise.
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Quoting JLPR2:


I guess that's dedicated to the dry air LOL!


Lets hope Gaston doesn't get too hyped up, I don't like how the Computer Models are trending Gaston toward the warmest waters in the Atlantic basin (Caribbean Sea, and I hope not the Gulf of Mexico in the very long range).
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1766. centex
Quoting TropicalAnalystwx13:


No. You would get some heavy rain, but nothing major.
I beg to differ.

NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1002 PM CDT SUN SEP 5 2010

...TROPICAL DEPRESSION 10 HAS FORMED IN THE SOUTHWEST GULF OF MEXICO...

.UPDATE...
THE TROPICAL SYSTEM LOCATED OVER THE SOUTHWEST GULF OF MEXICO WILL
LIKELY PRODUCE WIDESPREAD HEAVY RAINFALL ACROSS THE WESTERN HALF
OF OUR CWFA MONDAY NIGHT THROUGH WEDNESDAY AS IT MOVES NORTH
NORTHWEST OVER THE NEXT FEW DAYS. THE AREA ALONG AND WEST OF I-10
FROM JUNCTION TO SAN ANTONIO AND WEST OF I-37 FROM SAN ANTONIO
SOUTHWARD WILL HAVE THE HIGHEST RISK OF FLASH FLOODING. MAIN STEM
FLOODING OF THE RIO GRANDE IS ALSO LIKELY WITH RESERVOIRS CURRENTLY
AT OR ABOVE NORMAL POOL LEVELS.
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Quoting NCHurricane2009:


LOL, the only thing the Weather Channel teaches me is the pronounciation of storms. That's about it,



I think Gaston is listening to these lyrics from Christina Aguilera tonight, link

NO, I don't listen to Christina, but my younger sister does!


I use this site.
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1764. Patrap
Quoting Grecojdw:


Is there anything in the overall future pattern that won't prevent this from going strait into C.America?



I cant say as Im not a met.

I would follow the ATCF and NHC Guidance as they usually on the ball with track and intensity.

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yesterday our local abc weatherguy said this LOW wont effect us at all. now the station is saying localized areas could get up to 10 inches.. how strong do u guys think this system will get?
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1762. JLPR2
Quoting NCHurricane2009:


LOL, the only thing the Weather Channel teaches me is the pronounciation of storms. That's about it,



I think Gaston is listening to these lyrics from Christina Aguilera tonight, link

NO, I don't listen to Christina, but my younger sister does!


I guess that's dedicated to the dry air LOL!
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Thanks guys, if something bad happens I will show up some pics. Let's hope it's just some late-summer rain.
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Quoting Patrap:


Anything in the Caribbean in Sept..

U betcha we will keep one eye ball on it.


Is there anything in the overall future pattern that won't prevent this from going strait into C.America?
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Quoting KoritheMan:


Ah, possibly. I never knew Jimena was pronounced in that way. The more you know...


LOL, the only thing the Weather Channel teaches me is the pronounciation of storms. That's about it,

Quoting JLPR2:


It's trying harder tonight.


I think Gaston is listening to these lyrics from Christina Aguilera tonight, link

NO, I don't listen to Christina, but my younger sister does!
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Good night everyone!

Special Blog Update

Special Late Night Update: Tropical Depression #10 forms
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting JLPR2:


Well...
That makes me slightly uncomfortable. XD



Yup, this convection keeps growing a few more folks may be more uncomfortable tomorrow. UGH!
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Quoting AtHomeInTX:


Sorry to hear that. :( Hope it spares y'all the worst.


Hi AtHome.... :)
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Quoting Grecojdw:


It looks like he's going through another one of his bi-polar episodes...again.
LOL!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting mtyweatherfan90:
WOW, GFS brings TD10 right over my house!!!!




We´re still rebuilding the city from Alex and some landslides ocurred due to some heavy rainfall last friday and saturday so any more rain could cause some mayhem.


Sorry to hear that. :( Hope it spares y'all the worst.
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1753. Patrap
Quoting KoritheMan:


Gonna have to watch this one closely here in Louisiana eh, Pat?


Anything in the Caribbean in Sept..

U betcha we will keep one eye ball on it.
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Quoting Grecojdw:


It looks like he's going through another one of his bi-polar episodes...again.


I mean Gaston...forgot to point that out.
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1751. JLPR2
Quoting moonlightcowboy:
Gaston, Sept 5 evening


Well...
That makes me slightly uncomfortable. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting MiamiHurricanes09:
I think I can...I think I can...I think I can.... :)



yeah, and I think he will....
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Quoting MiamiHurricanes09:
I think I can...I think I can...I think I can.... :)



It looks like he's going through another one of his bi-polar episodes...again.
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1748. JLPR2
Quoting MiamiHurricanes09:
I think I can...I think I can...I think I can.... :)



It's trying harder tonight.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting Patrap:
00z Early Cycle NHC model tracks
Gaston
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)







Gonna have to watch this one closely here in Louisiana eh, Pat?
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Gaston, Sept 5 evening
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1745. KEEPEROFTHEGATE (Mod)
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1744. Patrap
GOM IR Loop

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I think I can...I think I can...I think I can.... :)

Member Since: September 2, 2009 Posts: 130 Comments: 21194
I see there's some talk about storms like Ginny 1961 and Noel 2007.

Those sorts of snow-making tropical "freaks" are more likely right in October and November. Why? Well, the warm Gulf stream hasn't cooled off as fast as the land mass of North America has by that time, that's because water has higher heat capacity than land (Oceans take longer to heat up, and then take long to cool down after that). So, you get a warm water current next to cold land mass, great source for east-west temp. constrasts and hence baroclinc instability for extratropical cyclones.

An Atlantic tropical cyclone can have a chance of developing strongly over the leftover warm waters in October or in some cases in November. It can then find itself moving quickly into a strong baroclinic (non-tropical) zone, and next thing you know, it finds itself suddenly mixing in enough moisture on the cold side of the baroclinic system to make snow.
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Quoting mtyweatherfan90:
WOW, GFS brings TD10 right over my house!!!!




We´re still rebuilding the city from Alex and some landslides ocurred due to some heavy rainfall last friday and saturday so any more rain could cause some mayhem.


Stay safe up there. Not sure that's going to mean much though, if you guys get as much as rain as I expect could occur...
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1740. Patrap
00z Early Cycle NHC model tracks
Gaston
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)





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WOW, GFS brings TD10 right over my house!!!!




We´re still rebuilding the city from Alex and some landslides ocurred due to some heavy rainfall last friday and saturday so any more rain could cause some mayhem.
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Quoting NCHurricane2009:


I think RecordSeason is remembering Jimena, which is an eastern Pacific name with that pronounciation.


Ah, possibly. I never knew Jimena was pronounced in that way. The more you know...
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Quoting NOSinger:


Read ...#1714


Thanks, post didn't show up fast enough. Should have known someone else would ask before me.
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It looked like a shading color up to Corpus

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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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