Ana and TD 3 take aim at the Lesser Antilles
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
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...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 18W S OF 16N MOVING W NEAR 15 KT.
ANALYSIS OF THE BAMAKO MALI UPPER-AIR TIME SECTION AND RECENT
5-DAY SATELLITE HOVMOLLER DIAGRAMS INDICATE THIS WAVE PASSED
BAMAKO NEAR 15/0000 UTC AND IS CURRENTLY PASSING DAKAR SENEGAL
AND EMERGING INTO THE FAR ERN TROPICAL ATLANTIC OCEAN WATERS.
LOW TO MIDDLE LEVEL CYCLONIC TURNING IS NOTED IN THE CLOUD MASS
IN CLOSE PROXIMITY TO THE WAVE AXIS WITH SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 7N-16N E OF 22W.
Whenever there are watches or warnings issued for a particular system, then you still have full advisories every six hours, but you also have intermediate advisories in between them. Ana has TS watches up for it; Bill does not. Intermediate advisories are not yet necessary for Bill.
Only the arrogance of youth would believe that the only way to become something is a degree. I know many people who have lots of pieces of paper, and can't fight their way out of a brown paper bag.
I got a new image 'cause that one wasn't showing up :(
I realize that, but something is going to have to change for him to make that bend.
sometimes you have to throw out the models and make your own forecast based on experience and whats actually happening. I expect Ana to continue towards the west northwest, reaching the islands by Sunday/Monday, Puerto Rico Monday, the Dominican Reb, Monday/Tuesday and Cuba by Tuesday/Wednesday. What ever is left of Ana after the land interaction emerges over the GOM in 5-6 days. How much is left will determine the degree of concern Ana posses in the GOM. There is still a chance Ana slide north of the islands, in which it could become strong TS.
Ana closer to land , and already tropical storms watches for the leeward Island?
the next update is 11PM but you can begin checking by 10:30
Arrogance of youth? LOL! Surely you jest.
Most names should end in 'ster :)
I agree, Monday night Bill will be virtually upon the islands.
I just cannot see it curving enough before the islands.
Adrian (hurricane23) and CCHSweatherman are very good too. Also, you can't forget our IKE, and StormJunkie. Lots of very respectable Wunderground mets on here :)
By the way, what does your Mom do with all your comments? I pull my kids' ear!
Yes, knowledge is great, but wisdom is far greater, for it is knowledge applied.
Looks like a cane, imo:
How about Little Ana and Bill the Brute?
I agree there needs to be a balance - but all the tools and latest technology learned - doesn't always equal experience. If this was an exact science - none of us would be lurking...
UZNT13 KWBC 152353
XXAA 65231 99173 70462 04176 99015 26640 09018 00128 25438 08023
92809 19615 09025 85539 21282 09023 70189 11064 10543 50589 09150
10521 40761 15566 09013 30971 30768 13523 25098 40763 15530 20246
53158 16510 15426 653// 14524 88999 77999
31313 09608 82326
61616 NOAA9 WX02A ANA OB 10
62626 SPL 1729N04628W 2341 MBL WND 08524 AEV 20801 DLM WND 11521
014145 WL150 08022 082 REL 1726N04619W 232631 SPG 1729N04628W 234
112 =
XXBB 65238 99173 70462 04176 00015 26640 11908 18823 22883 20866
33874 20860 44859 20865 55850 21282 66817 18863 77803 18263 88785
17876 99721 13067 11562 03321 22501 09148 33491 08164 44479 07377
55468 08177 66458 09559 77440 10971 88431 11566 99424 12175 11401
15366 22339 23769 33288 32768 44220 47957 55195 54559 66166 633//
77145 65942
21212 00015 09018 11984 08526 22934 08526 33906 09524 44874 08516
55850 09023 66705 10543 77541 10040 88504 11023 99487 07014 11475
08509 22465 04512 33459 04014 44420 08515 55330 14024 66301 13523
77287 16020 88258 15034 99202 16511 11182 15004 22166 16510 33153
13520
31313 09608 82326
61616 NOAA9 WX02A ANA OB 10
62626 SPL 1729N04628W 2341 MBL WND 08524 AEV 20801 DLM WND 11521
014145 WL150 08022 082 REL 1726N04619W 232631 SPG 1729N04628W 234
112 =
I don't know. It is in your opinion who you would feel is better.
What do you do now?
I was about to comment on that, It is still expose but not to the degree as earlier today.
Yeah, looks like a cane, a very nasty one too.
BILL:
Ana
Winds: 50mph
Pressure: 999 mbar
Bill
Winds: 65mph
Pressure: 994 mbar
Good answer...
That might be on the TWO by 8 AM tomorrow. Some models develop it. GFS and CMC are the two I think of off the top of my head.
I dont think Drakeon graduated yet from HighSchool last I saw... he maybe 17? not sure
A dense response for a dense question.
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