Ana and TD 3 take aim at the Lesser Antilles

By: Dr. Jeff Masters , 04:17 PM GMT on Αύγουστος 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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Quoting CaribBoy:
looks like Bill is now moving WNW


Yup.
Member Since: Posts: Comments:
Quoting tharpgomex:
just woke up to to TD 4..... I live in Panama City.... some of yall called this right yesterday!

Dont ever take your eye off of anything in ther gulf.
Member Since: Αύγουστος 31, 2008 Posts: 0 Comments: 833
4612. jdjnola
Quoting reedzone:
Will you guys stop saying Bill is a fish storm. It's heading west when models have it heading NW already. Bill still has a decent chance to affect the Eastern Seaboard, it's still 2 weeks away from impacting anybody if any. Models will shift back and forth, soon, I bet the models will shift south again. Dean was forecast to be north of the islands at that same spot, and it went south of there track.


Exactly. People forget between seasons that storms in specific and weather in general both have a pattern of behaving unexpectedly.
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4611. srada
Link

Good morning everyone..

What does the "M" mean on the tracking from NHC?
Member Since: Αύγουστος 17, 2006 Posts: 1 Comments: 774
looks like Bill is now moving WNW
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Quoting Beachfoxx:
OZ, I'm going to be driving the coast this evening, not by choice... but I will have cameras and video equipment with me.


It's email time...
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4607. TomSal
Quoting P451:
Both models curve Bill and still have him intense.
CMC still takes remnants of Ana and redevelops her in the Gulf.
CMC shows Claudette briefly heading due north to the FLA Panhandle.
CMC drops all Africa waves it seems.
GFS drops Ana and all waves off Africa for now.


00Z CMC



06Z GFS


Member Since: Posts: Comments:
I really don't get the pressure readings. Radar shows that bands are wrapping into the center of the depression. Dr. Lyons of the TWC says he doesn't expect the depression to strengthen all that much like the NHC thinks. He said a sign he sees is that the storms are not wrapping around on the northern side of the circulation which would indicate strengthening. I would have to ask me if he is seeing the same Tampa, FL radar as I am? Bands are wrapping into the west side of the circulation as well as southern and eastern sides. The northern circulation area is showing signs of organizing more, but there are no bands wrapping around on that side at this time. Eyewall could be forming. Don't be fooled by the weaker returns near its center, because there are large echoes on the eastern side of the storm between the Tampa, FL radar and the storm's center perhaps blocking it.
Member Since: Οκτώβριος 21, 2008 Posts: 246 Comments: 3970
TD#4 will be hitting the panhandle of Florida by 4 or 5pm. By then it should be claudette.
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just woke up to to TD 4..... I live in Panama City.... some of yall called this right yesterday!
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Quoting CycloneOz:


This is a worst case scenario in the making, though it will likely be much less than that.

A TC gets cooking on a Saturday, then blows up on a Sunday...then makes landfall before the work week begins.

Talk about a possible nightmare scenario...in my opinion...that's the worst possible.

Imagine if you decided to go camping on Friday...and you didn't listen to the radio.

Or...worst...you decided to go deep sea fishing, thinking everything was hunky-dory in the Gulf for the weekend.

Not good...
I have a tendency not to watch the news on the weekend or even have the TV on. I think I am not alone on this. Weekends are my get away from the world days. I am keeping up with the tropics this weekend but have looked at little local or national news.
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Quoting HaboobsRsweet:

Even though TD4 will most likely hit well to our east, it will bring up some of that nice tropical moisture and since it is already unstable out the wahzoo here, you cant rule out a full day of convection. I am not expecting a massive sotrm surge or strong winds but I do expect a day or two of rain.
I guess it is always possible. I just don't see it. Not enough with it IMO. You could be right though. I could use the rain myself...lol
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OZ, I'm going to be driving the coast this evening, not by choice... but I will have cameras and video equipment with me.
Quoting CycloneOz:


I'm 1500 miles out of position. And PensacolaDoug is celebrating his son's 15th birthday today...so he's out of position, too!

The entire XtremeHurricanes.com team is out of position for Claudette.

Not good....
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4598. Relix
Ana is having a heart attack. Seems she no longer can fight. Bill will have to fight whatever remains.... and IMO he won't make it as well. Probably a minimal TS at best.
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Bill is larger than ana so he can take more dry air. Tiny TS ana can't take that much dry air, but it is heading into a more favorable environment. TD4, I think with the hot waters of the GOM, I think it will be a mod to strong TS Claudette.
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4586. CycloneOz

Oz, good points! I have friends who left Friday to go to Port St. Joe to do some scalloping.... they are camping. Wonder if they have seen the forecast???
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Quoting futuremet:
CycloneOZ, are you going to film this?


I'm 1500 miles out of position. And PensacolaDoug is celebrating his son's 15th birthday today...so he's out of position, too!

The entire XtremeHurricanes.com team is out of position for Claudette.

Not good....
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Quoting CycloneOz:
Okay...where is the complaint department.

I have a depression that's spinning up into a TC and the ingredients for it to happen were all in place yesterday at this time...

I thought it was too. Watched it spinning on satellite and then radar from the very early morning hours yesterday. Then when the buoys had west winds, how could it not be a low? The pressures were not very low but relatively lower than the surrounding area. I guess that's all it takes. I'm no expert but have learned most of what I know from this blog when it comes to these starting.

I have followed the weather with great interest since childhood.

It was a pleasure watching it generate right on radar with this blog. Let's just hope it doesn't do much harm, and brings needed rain to someone who needs it. After all the rain it brought here, I know I won't have to water the tomatoes for at least today.
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Quoting ALCoastGambler:
I doubt TD 4 will add much to South MS weather other than a few showers. If it goes onshore in the Big Bend area anyway.

Even though TD4 will most likely hit well to our east, it will bring up some of that nice tropical moisture and since it is already unstable out the wahzoo here, you cant rule out a full day of convection. I am not expecting a massive sotrm surge or strong winds but I do expect a day or two of rain.
Member Since: Μάιος 20, 2009 Posts: 0 Comments: 1640
CycloneOZ, are you going to film this?
Member Since: Ιούλιος 19, 2008 Posts: 43 Comments: 4051
Morning everyone!
I see that we now have three players in Atlantic.
Member Since: Αύγουστος 9, 2009 Posts: 10 Comments: 5080
Quoting CycloneOz:
The Pensacola News Journal says nothing about Claudette this morning.

The NHC better hope that it doesn't spin up ala Humberto.

People will be screamin' "Why can't they predict a hurricane one day out!!!"
I remember folks at High Island going to bed thinking the next day it would rain. Boy they woke up to a surprise with 80 mph wind, rain and damage! I know many folks got caught with their pant down.
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4589. szqrn1
Quoting HaboobsRsweet:
I here thunder in Southern MS. Looksl ike more and more rain in our forecast and TD4 just going to add to it.


I am here too.... yep gonna be a wet one for us
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4588. Dakster
Quoting hahaguy:
I wake up to td4 in the gulf lol.


Good thing this is a "Dead" season that was written off by so many ppl here...
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Quoting HaboobsRsweet:
I here thunder in Southern MS. Looksl ike more and more rain in our forecast and TD4 just going to add to it.
I doubt TD 4 will add much to South MS weather other than a few showers. If it goes onshore in the Big Bend area anyway.
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Quoting Beachfoxx:
4560. CycloneOz 7:48 AM CDT on August 16, 2009

and that surprised you? The Journal probably went to publication before midnight.... I will check the NWFL Daily later, it won't mention the storm either, I am sure!

Looks like the panhandle will have an interesting evening... hopefully since the TD is already so close to land it will not have time to get stronger. I expect to see winds around 50 sustained tonight. YUK


This is a worst case scenario in the making, though it will likely be much less than that.

A TC gets cooking on a Saturday, then blows up on a Sunday...then makes landfall before the work week begins.

Talk about a possible nightmare scenario...in my opinion...that's the worst possible.

Imagine if you decided to go camping on Friday...and you didn't listen to the radio.

Or...worst...you decided to go deep sea fishing, thinking everything was hunky-dory in the Gulf for the weekend.

Not good...
Member Since: Posts: Comments:
I here thunder in Southern MS. Looksl ike more and more rain in our forecast and TD4 just going to add to it.
Member Since: Μάιος 20, 2009 Posts: 0 Comments: 1640
4583. hahaguy
I wake up to td4 in the gulf lol.
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Quoting stormwatcherCI:
LOL and Good evening(?) to you.

Good evening stormwatcherCI and to everyone else I bid you a Good Evening.
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4581. Grothar
I have been lurking the Experimental models for many years and it does not appear that the CMC is always that accurate. It either shows 10 category 5's (exagerating, of course) or nothing. From anyone's experience, of these models, which are usually the most reliable? Don't want to waste my time on conjecture.
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Again, models may shift south again, it's called trends. It's still a long ways away, models won't nail it that fast, sorry.
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Quoting AussieStorm:

enough with the polls already... they are getting a bit old and are a waste of space. my comment on ur poll is also a waste of space


really was a question aussie ....Geez
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http://www.wunderground.com/blog/fmhurricane2009/show.html
Please comment, this is a new blog, I hope you like it
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Quoting KEHCharleston:
On the Navy site - TD4 is Claudette


I haven't got it.
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Quoting KEHCharleston:
On the Navy site - TD4 is Claudette

I had a look... no Claudette yet
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I'm going to be back later

Tropical Update

LINK
Member Since: Ιούλιος 24, 2005 Posts: 407 Comments: 19076
Quoting TropicalNonsense:
there is a major south westward push by the bermuda high taking place right now.

this high is essentially the key player in bill and anna's track. the models are all currently way off with the intensity and oreintation and movement of this high. Bill and Anna may never see the trough 4-5 days out and may very well make landfall in south Florida if the high keeps digging in.


Florida Residents Stay Tuned to the Tropics .....









WOW, just what we want to hear !!!!!!!!!!!!
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4560. CycloneOz 7:48 AM CDT on August 16, 2009

and that surprised you? The Journal probably went to publication before midnight.... I will check the NWFL Daily later, it won't mention the storm either, I am sure!

Looks like the panhandle will have an interesting evening... hopefully since the TD is already so close to land it will not have time to get stronger. I expect to see winds around 50 sustained tonight. YUK
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Quoting AussieStorm:

enough with the polls already... they are getting a bit old and are a waste of space. my comment on ur poll is also a waste of space
LOL and Good evening(?) to you.
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I'm just a lurker but Ana reminds me a lot of Andrew.. How many times did he lose convection and was written off. Besides the fact that she is a woman and you all know we are persistent...
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4569. cg2916
Quoting boomerang08:
what would possibly be worst for ana?

1)going through the 30 knt shear in the caribean

2)crossing cuba or hispanolia

2
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Quoting Grothar:
TO:StormwatcherCI

Thank you for your honesty. Quite an admirable trait. I am not an expert either, which is why I ask so many questions rather than contribute. One would not like to appear a fool amongst so many who DO know.
Your welcome and I agree. Asking questions is how we will learn.
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Quoting CycloneOz:
The Pensacola News Journal says nothing about Claudette this morning.

The NHC better hope that it doesn't spin up ala Humberto.

People will be screamin' "Why can't they predict a hurricane one day out!!!"


If you look at the radar, it's doing just that, developing an eyewall.. Come on, lol.. water teps are 90 degrees and it's under an anticyclone, what do you expect?
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Quoting HaboobsRsweet:

On the last Metsat loop it looks like it is starting to turn ot the NW. That is a sign that maybe the models are correct.


agree
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Quoting P451:



Hmmm...well I do know one thing - Bill looks to be entering the same deadly dry air environment that Ana had done so in the past. I can't see Bill becoming a major hurricane or even a hurricane really while that is going on. He's clearly training in dry air from his NW it's wrapped around the south end of his inner core already.



Yes, but Anna is sort of moisturizing that area to the West for Bill, so it won't go through the exact same conditions.
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4564. Grothar
TO:StormwatcherCI

Thank you for your honesty. Quite an admirable trait. I am not an expert either, which is why I ask so many questions rather than contribute. One would not like to appear a fool amongst so many who DO know.
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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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