Ana and TD 3 take aim at the Lesser Antilles

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

Share this Blog
7
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 3864 - 3814

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97Blog Index

Quoting serialteg:


i know but the system has been going on since the cape verdes and it regenerates. so

thats a fact too.



Unrecognizable.


Member Since: Posts: Comments:
FYI... I just had a wierd crash with my computer... My screen kept flashing on and off with wierd lines...

Doing a full scan now... It may or may not be related to the blog. I was entering a link when it happened..
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Bill is up to 45mph.


dont see that here...

Member Since: August 22, 2006 Posts: 2 Comments: 1983
5am advisory will take 91L to TD. Tropical Storm warnings will be issued along the panhandle. Since we're 24 hours from landfall, they will be more inclined to upgrade quickly. Otherwise, warnings will be <24hours.
Member Since: Posts: Comments:
Tennisgirl, Stormno said to keep an eye on this in the GOM days ago, so i wouldnt be so quick to LOL.
Member Since: Posts: Comments:
I'm saying this as a reminder... DO NOT UNDERESTIMATE GULF STORMS. unless there is shear or something else to retard its rapid strengthening
Member Since: Posts: Comments:
Well just getting back from the Miss Gulf Coast and I have to tell you there are a lot of people upset that there is not much of a warning out yet and tomorrow will be to late....
Also the gas prices has gone up almost 10 cents from yesterday....

Taco :0)
Member Since: July 7, 2005 Posts: 6 Comments: 3261
Quoting WeafhermanNimmy:
Next advisory will all be the same for TS ANA and Bill!


Bill is up to 45mph.
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Tnumbers are at 1 which I think is too high.

Its moving way too fast to build convection. Those are the facts.


i know but the system has been going on since the cape verdes and it regenerates. so

thats a fact too.

Member Since: August 22, 2006 Posts: 2 Comments: 1983
Is there any chance that Invest 91L skips TD status and goes straight to TS. It looks damn impressive on radar.
Quoting victoriahurricane:
Is there any chance that Invest 91L skips TD status and goes straight to TS? It looks damn impressive on radar.


Does anyone know? I wasn't here for Humberto.
Member Since: Posts: Comments:
Quoting Weather456:


post the 5am advisory when it comes out. dont hit and run.


Sure I will be glad too. :)
Member Since: Posts: Comments:
After Ike us Houstonians dont need or want another one tyvm...lol
Member Since: Posts: Comments:
Quoting WeafhermanNimmy:
Next advisory will all be the same for TS ANA and Bill!


post the 5am advisory when it comes out. dont hit and run.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Patrap:

Hey Pat - I knew it! I went to sleep with local met saying "little chance of development" and BAM i's at red - what is going on? *still wiping eyes*
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Member Since: July 24, 2005 Posts: 407 Comments: 19076
can someone please post a link to the long loop nexrad radar on 91L thank you
Member Since: Posts: Comments:
Quoting stormno:
yes i certainly agree we have a depression now and by 5am we will probably have a strong tropical storm approaching hurricane force...i just looked at the latest satellite pics and radar from tampa and it is definitely moving nw maybe even a little wnw..i would say about 6-8 mph..this is certainly not goog for new orleans if it goes more wnw we will get the brunt of claudette and she will be over the water a lot longer...i agree a watch should come out at 5am or by 8am....the way its moving now i would think the watch would be as far west as lafayette and as far east as pensecola...this storm is growing rapidly in size also..not a good scenario...Stormno


what are you talking about?? its moving NNW and it isn't even named yet. LOL!!!!!
Member Since: Posts: Comments:
Next advisory will all be the same for TS ANA and Bill!
Member Since: Posts: Comments:
Quoting serialteg:
Quoting Stormchaser2007:
At this rate Ana will be gone by tomorrow.




crow talk :/


Tnumbers are at 1 which I think is too high.

Its moving way too fast to build convection. Those are the facts.
Member Since: Posts: Comments:
3844. Fshhead
Atlantic water vapor loop

Hmmm twin ULL'S awaiting Anna & Bill. Anna looks like she is starting to feel the influence. Man I hope Bill keeps a trucking for that area & the ULL'S hold.....
Member Since: Posts: Comments:
Drak bills shape looks like ike when he was forming last year. take into account how ana has set up the environment and u get another similarity to how ike former
Member Since: Posts: Comments:
Claudette (Humberto's cousin)? near the west coast of FL?
Member Since: Posts: Comments:
Quoting btwntx08:

did u see the two and the radar they confirmed a surface low


Radar imagery could easily show a mid-level circulation but I stand correct anyway since buoys show a circulation at the surface. I'll post it shortly.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CyberStorm:


no but the texas wishcasters are getting on standby and moving in to yellow alert


Really where????
Member Since: Posts: Comments:
Quoting stormno:
it indicates rapid development..im really getting concerned about this ..it still will be over the warm water for at least another 24 hourrs or longer if it slows down..this could be one for the books especially if it crooses the warm eddy just off the la coast..i was afraid of this happening..Stormno


me too
Member Since: Posts: Comments:
Quoting drj27:
well if it hits pcb then we should be ok in okaloosa county i hope
I wouldn't blink. I think anywhere in the panhandle could be impacted.
Member Since: Posts: Comments:
d max in 2 hours gonna throw some gas on 91l
Member Since: Posts: Comments:
3834. TX2FL
Quoting Drakoen:
This season doesn't seem to want to stop. The ECMWF 00z wants two more systems to form in the tropical Atlantic.


What's it doing with Bill? Still wanting to recurve it? I figure it's way to early to plan not to plan..
Member Since: Posts: Comments:
Models indicate landfall in the Florida panhandle around midnight tomorrow.
Member Since: Posts: Comments:
Quoting Stormchaser2007:
At this rate Ana will be gone by tomorrow.




crow talk :/
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Conditions at 42013 as of
(1:40 am EDT)
0540 GMT on 08/16/2009:


Wind Direction (WDIR): SE ( 140 deg true )
Wind Speed (WSPD): 23.3 kts
Wind Gust (GST): 23.3 kts
Atmospheric Pressure (PRES): 29.98 in
Water Temperature (WTMP): 86.2 °F


Station 42036
NDBC
Location: 28.500N 84.517W
Conditions as of:
Sun, 16 Aug 2009 05:50:00 UTC
Winds: E (90°) at 19.4 kt gusting to 25.3 kt
Significant Wave Height: 3.3 ft
Dominant Wave Period: 5 sec
Mean Wave Direction: ESE (112°)
Atmospheric Pressure: 29.97 in and falling
Air Temperature: 84.4 F
Dew Point: 75.9 F
Water Temperature: 86.2 F
Member Since: Posts: Comments:
Texas hurricane, dont know thats the point.
Member Since: Posts: Comments:
Quoting neonlazer:

Where did you find that?..link? :)


Link
Member Since: Posts: Comments:
3828. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128879
3827. drj27
can someone post a link to the radar
Member Since: Posts: Comments:
Quoting Stormchaser2007:
Latest surface wind obs show some 30 knot winds with an isolated 35knot barb.


Where did you find that?..link? :)
Member Since: Posts: Comments:
Quoting hurricaneguy87:
Can't believe there are no trolls saying that 91l will "break up" or its a fish, next! lmao


no but the texas wishcasters are getting on standby and moving in to yellow alert
Member Since: Posts: Comments:
Quoting Drakoen:
This season doesn't seem to want to stop. The ECMWF 00z wants two more systems to form in the tropical Atlantic.


Well it may not have a huge window for development, trying to squeeze out what it can.
Member Since: Posts: Comments:
Is there any chance that Invest 91L skips TD status and goes straight to TS? It looks damn impressive on radar.
Member Since: Posts: Comments:
Quoting Patrap:
Somebody's gonna Have a Close Encounter with a Tight,Cyclone,...Possibly a Hurricane,with a Night Landfall if I did my lil quick Math Right,..



Ugh! Nightfallers are the worst!!!
Member Since: Posts: Comments:
Quoting stormsurge39:
I dont know if we need to go strictly off models right now. Just watching it shows alot.


Where would you think it would go then?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
456 do you mean it looks stronger than what it might be?
Member Since: Posts: Comments:
3818. Drakoen
This season doesn't seem to want to stop. The ECMWF 00z wants two more systems to form in the tropical Atlantic.
Member Since: Posts: Comments:
Quoting tennisgirl08:
Models are very accurate on storms that have formed and where they are going within 1-2 days. 91L is going to the panhandle!

This storm has formed a low level circulation so recently, the models could not have had an exact point of initialization when they were run. The models take hours to run, and data has changed dramatically since this info was input. That said, the panhandle is obviously the probable landfall point. Don't need a model for that!
Member Since: Posts: Comments:
Ana looks like it's racing thru the upper windwards and tracking south of PR.
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Quoting stormsurge39:
Its definitely moving more W of N than an hour ago.


It is moving NNW with 35mph winds.
Member Since: Posts: Comments:
Quoting stormsurge39:
Its definitely moving more W of N than an hour ago.


You are looking at radar right? because I don't see that at all
Member Since: Posts: Comments:

Viewing: 3864 - 3814

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.