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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Quoting AllStar17:
'

Yuck. Those tracks would be horrible...especially if it got into the W. Caribbean.

I really do not understand why the NHC went with 60% because of dry air. At most, it should have dropped to 70%, if at all. It is moving west and into a more favorable environment, yet they lowered the percentages. Not to mention, it does have convection over the center.

I also do not believe 90L should have gotten 80%. They should have kept it at 60%.

Very confused by this TWO issued by Blake.
Read post 1071. :D
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Quoting MoltenIce:
Moist environment in front of Gaston is moist.


The ULL in front of Gaston is pulling moisture up from the south, probably what the NHC thinks will provide him with a better environment in the future.
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A bit off-topic, but has any tropical cyclone stayed tropical while over Labrador? Earl came close. It's the first time I've ever included Labrador on a hurricane graphic:
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1130. Vero1
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 05 2010

...TROPICAL WAVES...

TROPICAL WAVE REMAINS INLAND OVER WEST AFRICA ALONG 11W MOVING W
NEAR 10 KT. A 1009 MB LOW IS ALONG THE WAVE AXIS NEAR 9N11W.
THIS SYSTEM IS EXPECTED TO ENTER THE ATLC OVER THE NEXT 24 HRS.

...ITCZ...
A MONSOON TROUGH IS S OF 20N E OF 30W TO W AFRICA. AN ITCZ AXIS
CONTINUES WESTWARD FROM 8N30W TO 8N40W 12N60W. SCATTERED
MODERATE TO STRONG CONVECTION IS FROM 9N-15N BETWEEN 15W-19W.
WIDELY SCATTERED MODERATE CONVECTION IS FROM 6N-10N BETWEEN
20W-26W...AND FROM 3N-6N BETWEEN 26W-32W. SCATTERED MODERATE
CONVECTION IS FROM 6N-8N BETWEEN 35W-40W.

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Quoting AllStar17:
'

Yuck. Those tracks would be horrible...especially if it got into the W. Caribbean.

I really do not understand why the NHC went with 60% because of dry air. At most, it should have dropped to 70%, if at all. It is moving west and into a more favorable environment, yet they lowered the percentages. Not to mention, it does have convection over the center.

I also do not believe 90L should have gotten 80%. They should have kept it at 60%.

Very confused by this TWO issued by Blake.
Yeah, Blake likes to mess around this us. He's the same guy that did the 0%-60%-0% with 95L. He just likes to go with how things are that very second instead of looking for trends.

Though, due to the dry air, it may not develop during the next 48 hours.
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Quoting StormW:


SE coast of where?

I haven't looked at the models on that yet...but seems to me with the trend, they'd want to recurve something if it formed on the other side of the Equator.
Im sorry I meant SE US coast //Florida etc.
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another intersting week lies ahead!!
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Quoting MiamiHurricanes09:
Hey good evening Kman! We currently stand at ex-Gaston 6.0. Check out the 18z dynamical models...they shifted towards the left...a lot.

'

Yuck. Those tracks would be horrible...especially if it got into the W. Caribbean.

I really do not understand why the NHC went with 60% because of dry air. At most, it should have dropped to 70%, if at all. It is moving west and into a more favorable environment, yet they lowered the percentages. Not to mention, it does have convection over the center.

I also do not believe 90L should have gotten 80%. They should have kept it at 60%.

Very confused by this TWO issued by Blake.
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Quoting Vero1:
NOT Good!!



From what I've learned here, it's a bit early to have models of where it could hit? I really dislike number 16, but for the next couple of days, I don't worry at all from these models.
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If the trend continues, Gaston could move south of the big islands and then could end in the GOM and that's a really scary scenario.
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1121. Vero1

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 05 2010

...SPECIAL FEATURES...

A 1009 MB LOW...REMNANT OF GASTON...IS ABOUT 550 NM E OF THE
LESSER ANTILLES NEAR 17N51W MOVING W NEAR 10 KT. SATELLITE
IMAGERY INDICATES A LOW LEVEL SWIRL WITH SMALL CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION TO THE W FROM
16N-18N BETWEEN 52W-54W. ALTHOUGH ACTIVITY IS CURRENTLY
LIMITED...ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR
DEVELOPMENT OF THIS SYSTEM AND A TROPICAL DEPRESSION COULD
RE-FORM DURING THE NEXT DAY OR TWO. THERE IS A HIGH CHANCE OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE AGAIN DURING THE NEXT 48
HOURS.

A 1005 MB LOW OFF VERACRUZ MEXICO IS NEAR 20N96W. A TROUGH
EXTENDS N FROM THE LOW TO 26N95W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE FROM 19N-26N BETWEEN 93W-99W. SHORT RANGE
COMPUTER MODELS SUGGEST THIS SYSTEM WILL CONTINUE TO MOVE NNW
OVER THE NEXT COUPLE OF DAYS. ENVIRONMENTAL CONDITIONS APPEAR
FAVORABLE FOR ADDITIONAL DEVELOPMENT AND A TROPICAL DEPRESSION
COULD FORM DURING THE NEXT DAY OR SO BEFORE THE SYSTEM MOVES
INLAND. THERE IS A HIGH CHANCE OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS
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Quoting Vero1:
NOT Good!!

Moving WSW? That's "NOT Good!!"

Quoting kmanislander:


Sorry it took so long to reply. The blog is taking firever to laod. I saw that, not a good sign if he egts his act together.
Don't worry about it. Yeah, hopefully he stays weak, but the Caribbean looks like prime spot for deepening.
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1119. dayton
Thank you, StormW, for answering my questions in a simplistic way! Sometimes, people on here are so confusing, I can't figure out what they are trying to say!! No, I'm not dumb...just don't know all the terms that are used here!
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Quoting stormwatcherCI:
Gaston did not dissipate. He lost his convection but still had his circulation.

True.
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Moist environment in front of Gaston is moist.
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Quoting cyclonekid:
I never said they weren't right all the time. Look at Gaston for example. They were expecting it to reach Category 2 intensity and it dissipated the next day. But I'm saying trust them because MOST OF THE TIME meaning 99% of the time, they are correct. They really did do a good job of predicting Danielle and Earl for example.
Gaston did not dissipate. He lost his convection but still had his circulation.
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Quoting MiamiHurricanes09:
Hey good evening Kman! We currently stand at ex-Gaston 6.0. Check out the 18z dynamical models...they shifted towards the left...a lot.



Sorry it took so long to reply. The blog is taking firever to laod. I saw that, not a good sign if he egts his act together.
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looks like the caribean islands could be in for some interesting kind of weather this week with the models putting gaston to ride throught the caribean..
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1111. Vero1
NOT Good!!

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Thanks MH09.
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Quoting clwstmchasr:


We can trust them and respect them but they are not always right.
I never said they weren't right all the time. Look at Gaston for example. They were expecting it to reach Category 2 intensity and it dissipated the next day. But I'm saying trust them because MOST OF THE TIME meaning 99% of the time, they are correct. They really did do a good job of predicting Danielle and Earl for example.
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Well now the switch numbers, now is ex-Gaston down to 60% and GOM disturbance up to 80%,in route to hit NE Mexico... Gaston probably a rain maker to the leewards... after that when he gets to the Western caribbean has a possibility.
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Quoting kmanislander:


Yeah, the steering should take Gaston well into the Caribbean. The game was great but was it ever hot out there. Can't wait for the cool down to happen.



When do you get your first cool weather there? It is usually the beginning of Nov. here in S. Fl.
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Quoting kmanislander:


Yeah, the steering should take Gaston well into the Caribbean. The game was great but was it ever hot out there. Can't wait for the cool down to happen.

Temp today 93F with a heat index of 105F. This has been one hot summer.
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Evening Storm..hope you are having a good weekend!!! Just wanted to ask if you feel Gaston could pose a threat down the road to the southeast coast?? I also see the models forming another system off africa next few days but seem to want to recuve it???
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1102. Vero1
Quoting xcool:


The model are continuing their westward trend
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The blog is really messed up. Double posting and taking forever to load
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1100. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15648
.
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Hi Storm! Thanks for the update on Gaston. I'll be keeping an eye on him.
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I wouldn't be surprised if the NHC goes ahead and upgrades 90L tonight...they seem bored after having to deal with 3 simultaneous tropical cyclones.
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1088...I like that...
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Quoting stormwatcherCI:
Models have shifted into the Caribbean now also. How was your game ?


Yeah, the steering should take Gaston well into the Caribbean. The game was great but was it ever hot out there. Can't wait for the cool down to happen.

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Quoting StormW:


Well, today I had mentioned I expected his waxing and waning to continue for the next 36.

Here is from my forecast yesterday:

Based on analysis of various satellite loop imagery channels, current and forecast wind shear products, and SST's, I expect the remnant low to either maintain it's current status, or even weaken over the next 12-24 hours. The main culprit here is going to be dry air.

Based on water vapor loop imagery, and warming SST's to his west, conditions may improve during the next 48 hours, as an upper level trof backs to the WSW, and eventually lifts out. During this process, the ULL will aid in continued ventilation of the remnant low.

Save any serious dry air intrusion, I don't look for "Gaston" to really begin to improve for about another 48 hours. Thereafter, the remnant low should be under the influence of an established upper level anticyclone, and organization could become a more steady pace.


Thank you, sounds like you have a solid call, as usual!
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1092. dayton
To StormW: I know this may sound like a juvenile question, but, I'm just an interested person - no expert...and it's hard to sometimes pick out the experts on this board (except for you)...and that is why these questions are directed to you. What do think the chances are that Gaston affects the US? What do you think the chances are of having a US hurricane strike this season?
Thank you in advance for answering.
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Interesting flip flop. Gaston down to 60% while 90L goes up to 80%.
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1090. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15648
Quoting StormW:
Yep...that's it boys and girls...let's go home...the season is over.




just lurking and had to comment on this one.

That's Good Storm! ROFL!
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Quoting StormW:
Yep...that's it boys and girls...let's go home...the season is over.




The models show nothing through November 30th...
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Quoting futuremet:


Typed too fast lol.


I would rather have good info than the eiditors cut!
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Amen well stated.

Quoting ShenValleyFlyFish:
if folks would just goe through a 3 part ritual every time one of these guys appears life would so much better.
#1. hit the red flag ! this alerts admin that there is an issue.

#2. hit the minus - if enough members do this person is basically voted off the blog and may not reappear if admin bans.

#3. if reappears hit the ignore as may be a personality issue between you and poster and others may not find as annoying as you but hey life is too short to be aggravated while engaged in what is supposed to be a pleasurable activity.

Every quote or response to a troll is a vote for them to stick around. They want to piss you off and wallow in your abuse because it means they got to you. Don't play their game you loose every time.
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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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