Ana and TD 3 take aim at the Lesser Antilles

By: Dr. Jeff Masters , 4:17 PM GMT on August 15, 2009

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Tropical Storm Ana was born this morning, when the remnants of Tropical Depression Two made a comeback and organized into the first tropical storm of the 2009 Atlantic hurricane season. Ana is the latest first named storm of the season since Hurricane Andrew got its name on August 17, 1992. The two storms have some similarities, as Andrew formed in the same part of the ocean, and also struggled in its early days with high wind shear and dry air. Let's hope the similarities end there.

Ana is struggling this afternoon. After an modest burst of heavy thunderstorm activity prompted NHC to upgrade Ana to a tropical storm early this morning, Ana has run into strong upper-level winds from the west that are creating high wind shear. This shear was not forecast, and it is not clear how long it will last. The shear has acted to drive dry air into the core of Ana, destroying almost all of Ana's heavy thunderstorms. The low-level center of the storm is now exposed to view, something that often foreshadows the death of a storm. It is possible the shear will destroy Ana, and several models (the GFS and ECMWF) forecast this may be the case. However, the shear forecast calls for shear to drop into the low range, 5 - 10 knots, tonight through Tuesday. If the shear does drop as forecast, Ana should be able to moisten the atmosphere around it sufficiently to protest itself from the dry Saharan air that surrounds it (Figure 1). SSTs are 27°C today, and will increase to 28°C by Sunday. By the time Ana moves into the Bahamas, total ocean heat content rises steeply (Figure 2), and rapid intensification of Ana is possible, if the shear and dry air haven't disrupted the storm. The intensity forecast models, for the most part, predict a steady intensification of Ana to the threshold of hurricane strength five days from now. The HWRF model is on the strong side, predicting a Category 2 hurricane. The GFDL predicts a weak tropical storm five days from now, but that is because the model has Ana passing over the rugged terrain of Hispaniola, something the other models do not predict. In summary, the intensity forecast for Ana has higher than usual uncertainty, and I give equal chances that the storm will be a hurricane--or non-existent--four days from now.


Figure 1. Water vapor image from this morning showing the large area of dry, Saharan air surrounding Ana, and lying to the north of Tropical Depression Three. Image credit: NOAA/SSD

Tropical Depression Three forms, could be Bill later today
QuikSCAT data from this morning and satellite loops revealed that the tropical wave (90L) in the middle Atlantic has finally developed a well developed surface circulation and can be classified as Tropical Depression Three. Recent satellite imagery suggests that TD 3 may already be Tropical Storm Bill. Water vapor imagery (Figure 1) shows that TD 3's center consolidated a few hundred miles south of the dry air of the Saharan Air Layer (SAL). Thus, the storm should not be affected by dry air and dust as much as Ana has been. Ana may also act to moisten the atmosphere in front of TD 3, helping protect the storm from the SAL as it edges farther north over the the three days.



Figure 2. Heat content of the ocean, in kJ per square cm. Oceanic heat content steadily increases for Ana and TD 3 as they approach the Lesser Antilles Islands. Oceanic heat content levels of 90 kJ per square cm are frequently associated with rapid intensification of hurricanes. Image credit: University of Miami.

Wind shear is moderate, 15 knots, but is forecast to fall to 10 - 15 knots on days 2 - 5. Sea Surface Temperatures are about 27.5°C, and will remain in the 27.5 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow TD 3 to intensify steadily, and I expect the storm will be at hurricane strength by Wednesday, when it will be near the northern Lesser Antilles Islands. Most of our reliable intensity models strengthen TD 3 into a hurricane by Wednesday. Oceanic heat content (Figure 2) increases sharply just before the islands, so TD 3 could be intensifying rapidly as it moves through or just north of the Lesser Antilles on Thursday. TD 3 consolidated farther south than expected, so the track models calling for a more northerly path were probably incorrect. In particular, the ECMWF model, which had TD 3 turning sharply northwestward and missing the Lesser Antilles Islands, was probably much too far to the north in this morning's 00Z run. TD 3 will probably pass very close to the northern Lesser Antilles islands on Wednesday and Thursday.

I'll have an update Sunday.

Jeff Masters

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Bill has a 19% chance of becoming a cat 3 in 5 days, that is pretty high for a cat three at 5 days.

Most storms settle with less than 1 and 5 percent while others that surprisingly became majors quickly (Charley) had less than 15%.
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Tropical Storm Bill is the most likely disturbance or cyclone in the Atlantic to become the next or first hurricane of the season. However I don't expect it to happen tomorrow but maybe Monday. Why? Because there is still dry and stable air on the north side of the circulation. Given that storms are developing within this region the dry air should become less of a factor as we head into tomorrow. The large storm center is interesting and a reason why it hasn't gone through any rapid intensification. Once the moisture is engulfed within Bill's circualtion I expect it to then take off. When will this occur I don't know, but it could happen fairly quickly tonight. DMAX will be a surprise tonight.
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System off Africa too far north..anything that exist Africa around 15N generally ends pulling north! Before people jump on me, I did say "generally"!! :)
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Quoting Chiggy007:
20% chance is pretty low...what that means is that most likely it WON'T be a hurricane tomorrow..FAR FROM IT!!


It only has to go up 1.5 more to attain hurricane status. If it went up just 0.5 each advisory that would be just 3 more.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
does anyone have a link to the UKMET model page and the NOGAPS model page/ thanks for any links
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Here's hoping the models are right & Bill will pass N of us here in the islands. Lots of people have been laid off in the last few weeks so rebounding from a hurricane will not be easy in these very vunerable islands.
Recently the natural curve N by systems tracking our way has been false hope with the two big ones defying the norm. Ivan decided to track S & destroyed Grenada & more recently Dean levelled off & blasted Martinique & Dominica. To be honest I don't see Bill curving fast enough to miss us unless strengthening occurs rapidly in the next 2 days. I see rapid strengthening occuring much closer to the chain by which time a target will be locked on. GOOD LUCK fellow islanders!!
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1256. juniort
What about the system coming off Africa now, looks quite impressive!!
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Quoting claimsadjuster:


It looks that way. Mobilegirl. are you getting the same feeling I am about this. It has been a long time since we here in Mobile have took a direct hit.

Could be a threat with an appetizer(rainmaker in the gulf now moving this way)to go along with it.
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1254. KEEPEROFTHEGATE (Mod)
Quoting kingzfan104

Do No Harm

I will not attack, embarrass, humiliate, or make others fear for their safety

I will respect my readers, critics, and subjects of my posts. I will discuss and answer all people with respect, regardless of age, sex, race, religion, nationality, ability, attractiveness, and social or economic status or mental state
Member Since: July 15, 2006 Posts: 175 Comments: 54880
20% chance is pretty low...what that means is that most likely it WON'T be a hurricane tomorrow..FAR FROM IT!!
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guys the recon aircrafts are out
Decoded recon data in the last 30 minutes:

Non-Tasked Mission Data (for at least one product)
Updated on our site 19 minutes ago
08/15 Td2 NOAA N49RF UZNT13
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Quoting superweatherman:


Hey weather456 do you think if ANA does fallow the models of going to the GOM how strong you think it will get? and where you think it will headed...


if it survives intact, the reults of Ana in the Gulf is not good. Rather, I dont want it nor Bill to enter the GOM. The energy stored there is enough produce Katrina-Rita storms.
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Quoting Weather456:
Also, El Nino may have peaked in late July. I hinted this may have occured in a El Nino blog I had in July



Im not surprised.
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Quoting Weather456:
At the current rate of organization, Bill could be a hurricane as early as Sunday.

Yep...NHC gives it a 20% chance to do just that.
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South Florida is still well in the cone for Ana. Do not discount it. A hurricane landfall is still possible.

I'm not starting hype, but everyone in the cone of this system should be prepared. If it doesn't hit you, then you will be prepared for Bill or potentially Claudette.
Member Since: July 10, 2006 Posts: 27 Comments: 1623
Quoting jasoniscoolman10:
SATELLITE IMAGES INDICATE THAT TROPICAL DEPRESSION TWO HAS
STRENGTHENED AND HAS BECOME TROPICAL STORM BILL..$
FORECASTER AVILA


Avilla has been working too hard! LOL

TD2 - A
TD3 - B

:)
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1243. 996tt
Quoting rareaire:


based on? its kind of far off for that kind of talk dont you think?


Strength and trough that this recurve Bill will will be moving East.
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Also, El Nino may have peaked in late July. I hinted this may have occured in a El Nino blog I had in July

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Post #1233 reported.

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1240. hahaguy
Quoting superweatherman:


Hey weather456 do you think if ANA does fallow the models of going to the GOM how strong you think it will get? and where you think it will headed...


On the path it's on now it probably wouldn't make it into the gulf if it went over Haiti/DR and cuba.
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Re: 1233


Uncalled for dude.
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Quoting 996tt:


This one actually looks big. It will recurve though.


based on? its kind of far off for that kind of talk dont you think?
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Weather456:

You are one of the ones I respect hugely on here but your latest statement about BILL being a Hurricane by tomorrow..REALLY?
Highly unlikely...braod circulation, north side completely open, lack of convection apart from the recent blow-ups...not seeing it AT ALL..
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1234. Patrap

The turbulent flow patterns of an intensifying hurricane. From NASA's Scientific Visualization Studio.


Member Since: July 3, 2005 Posts: 426 Comments: 129093
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Lifted from Joe Bastardi's blog this afternoon. Enjoy!

SATURDAY 5 PM

RAPID FIRE FEEDBACK TRYING TO REV UP HOME BREW IN SOUTHEAST GULF.

I do have Gulf-a noia... the fear of a storm getting into the gulf and going haywire. I have been watching waves this year and noticed that the 2 we can look at have blown up quite a bit on the their way to the coast. A well established storm over the Fla starits could be a real problem this year, even more so than others.

Another example is occuring before our eyes as the tropical wave in the southeast gulf is organizing and quite fast. but above the surface right now. The PSU look pis vivid with the banding features

http://www.meteo.psu.edu/~gadomski/SAT_SE/anim16vis.html

I want to make sure you understand why I am like this. Humberto for instance was a product of one system that split, the eastern side resulted in Gabrielle, the bottom part of the wave got into the area that Erin below up at the last minute. TPC fell asleep, and tried to play it off as rapid development, when in reality the pressure drop was 20 mb in some 20 hours.. respectable but nothing that hasnt happened before. The problem is they wrote the wave off and did not realize that it was approaching storm intensity at 3 am in the morning when we warned our clients. It was described, by one of my friends in the field as an almost mesoscale event. True enough but it came out of a trackable wave that hit its stride. This year is like that in the gulf... fortunately this will be onshore by late tomorrow night.. Unfortunately, if it gets down to the surface and really starts feeding back, it is embedded in high pressure so a 15-20 mb drop would lead to the same kind of excuse. I am on their case about this, because Humberto was predictable if one understood what was going on. I specifically posted that evening as to WHY the convection had fallen apart in the afternoon, a situations that happened in Bob in 1991 as a weak 150mb trough crossed over the storm and capped the upward motion, but once by, off it went.

While a powerful hurricane in this area moving nnw would weaken, a weak system can intensify since its well below the threshold of maximum intensity in the eastern gulf for a storm, which north of Tampa and east of 85 west, may be a cat 2 due to the rapid cooling of water with strong east winds off land, and entrainment of dry air with a strong hurricane paralleling the coast. However a small system can ramp up to a certain level.

The system is suffering now from competition from tstorms over land, but later tonight we may see a big comeback. The Key West radar is very interesting

http://radar.weather.gov/ridge/radar.php?product=N0R&rid=BYX&loop=yes

So folks between the se tip of La and the Fla coast east far east as Cedar Key should watch close here. While one may be going bananas over Ana, and getting a thrill over Bill, there si a chance by tomorrow night we may have to fret, if this feedback and is trying to become Claudette. Given long enough odds, make the bet ( it is a bold idea)..

Lets see if we get the hatched area to go to moderate.

In the end, it may be a tool to use if we get an established system in there.
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1230. 996tt
Quoting Weather456:
Here comes another



This one actually looks big. It will recurve though.
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Quoting mobilegirl81:
So ana could be a gulf storm?


It looks that way. Mobilegirl. are you getting the same feeling I am about this. It has been a long time since we here in Mobile have took a direct hit.
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Quoting Weather456:
Here comes another




Wow, that one looks pretty good!
Member Since: July 2, 2009 Posts: 0 Comments: 2811
In a way I'm surprised that tropical storms/hurricanes can form at all. There are SO MANY factors that have to come to play....
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Here comes another

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1224. Patrap
Tropical Storm Bill Storm Relative 1km Geostationary Visible Imagery

Time of Latest Image: 200908151945




Storm Relative 1km Geostationary Visible Imagery

The current suite of geostationary satellites provides visible imagery during daylight hours at higher resolution than many of the infrared channels. Such imagery is useful, especially when animated, for position estimation and monitoring the degree of convective organization. The native visible imagery has been remapped to a one-km Mercator projection and the digital data has been stretched over its full range - allowing a more esthetically pleasing appearance. The center location is based on the last operational position estimate and the previous 12-hr motion.
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting KEEPEROFTHEGATE:
he knows nothing ws except what the book tells him and in reality the book is meant as guidance just like the models
Quoting KEEPEROFTHEGATE:
he knows nothing ws except what the book tells him and in reality the book is meant as guidance just like the models
Plus he is not the only one on here that knows his stuff and WS interprets things that way he wants to see it.
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At the current rate of organization, Bill could be a hurricane as early as Sunday.

Meanwhile, future 91L is a very virgorous wave off the coast of Africa

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1221. 996tt
The keys disturbance or wave has all but fallen apart.
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Speaking from a hunch - just a hunch - and therefore don't annihilate me blog members, I think, believe Ana will get ripped apart by the mountains of Hispaniola. The storm has been asking to be put to sleep since her departure from the coast of the Cape Verde islands. I almost want the storm to just die already. It is so annoying to look at how pathetic it has been doing... L O L
I dont wish nor prefer a powerful storm to impact any population center, I just like observing the formation of tropical systems because it is a phenomenon happening mostly during hurricane season and they are interesting atmospheric events. You know, this is Earth and it is a complex matter worthy of being curious about.
Member Since: July 27, 2009 Posts: 0 Comments: 96


Hey weather456 do you think if ANA does fallow the models of going to the GOM how strong you think it will get? and where you think it will headed...
Member Since: July 18, 2009 Posts: 0 Comments: 307
http://forums.accuweather.com/uploads/post-16078-1250369937.gif

Fish still a strong possibility
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Quoting mobilegirl81:
So ana could be a gulf storm?


Looks like it could be.....
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting Weather456:


same here, after it sped it, its location and motion,


Afternoon 456,Guess you have been busy all day preparing........AS it stands, it is my opinion and don't see Bill pasing as far North as Dominica. I see a central passage!!! What's your take on this?
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Quoting Fshhead:


Your kiddin' right??? Waaay to early to say that!
Not for him. He has the inside track on where every storm will go. LOL
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If it goes over Cuba/DR its tiny circulation will be done.
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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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