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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...and what happens when Ana gets inthe Gulf?!
Yep Yep. I hope we will be spared this year...
Tropical Disturbance Summary (1800z 15AUG)
=========================================
At 3:00 AM JST, Developing Low, Former Tropical Depression Etau (1000 hPa) located at 43.0N 179.0E is reported as moving east at 40 knots
FINAL FROM WWJP25
---
On its way to Alaska.
ANA
TD3
AOI
sure hope so
Basements. If I remember correctly coffee was on here last year and called out Gustav too.
IF YOU DO NOT UNDERSTAND THIS PLEASE VISIT THIS LINK: Link
UZNT13 KWBC 152315
XXAA 65231 99165 70504 04260 99012 26824 ///// 00106 26021 09025
92790 21214 10030 85521 18229 10036 70163 09217 10538 50588 05356
07523 40760 16350 07523 30971 30950 09016 25097 41361 17513 20245
53561 16521 15425 643// 19502 88999 77999
31313 09608 82251
61616 NOAA9 WX02A ANA OB 07
62626 SPL 1655N05053W 2306 LST WND 017 MBL WND 09026 AEV 20801 DL
M WND 10520 010145 WL150 09024 091 REL 1653N05043W 225114 SPG 165
5N05053W 230614 =
XXBB 65238 99165 70504 04260 00012 26824 11914 20613 22850 18229
33803 15826 44761 14060 55731 11857 66717 11062 77695 08812 88678
08456 99660 07029 11652 06858 22646 06250 33622 04460 44611 03856
55581 01862 66554 00763 77541 02356 88532 03158 99527 03549 11478
07948 22471 08356 33462 09167 44450 10538 55445 11129 66415 13958
77405 15545 88395 16757 99383 18122 11351 22350 22329 25758 33303
30156 44267 37356 55242 43164 66224 47750 77194 55162 88170 619//
99145 65150
21212 00012 ///// 11010 09023 22975 09528 33850 10036 44651 10545
55599 08537 66514 08528 77433 06019 88414 08021 99381 08016 11359
06512 22314 10011 33290 09013 44265 13506 55255 17510 66231 19514
77206 16021 88182 16527 99170 15034 11160 18007
31313 09608 82251
61616 NOAA9 WX02A ANA OB 07
62626 SPL 1655N05053W 2306 LST WND 017 MBL WND 09026 AEV 20801 DL
M WND 10520 010145 WL150 09024 091 REL 1653N05043W 225114 SPG 165
5N05053W 230614 =
You can say a lot of things about StormW... but to say he "guessed" is not one of them.
Poof
Tropical Disturbance Summary (1800z 15AUG)
=========================================
SUBJECT: Tropical Depression Near Marshall Island
At 3:00 AM JST, Tropical Depression, Former Maka (1008 hPa) located at 14.6N 173.2E has 10 minute sustained winds of 30 knots with gusts of 50 knots. The depression is reported as moving north-northwest at 6 knots
Location: 14.4°N 50.4°W
Max sustained: 40 mph
Moving: W at 17 mph
Min pressure: 1004 mb Per the NHC
First time I have laughed all day on the blog!!!!!
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SAT AUG 15 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM ANA...LOCATED ABOUT 735 MILES EAST-SOUTHEAST OF THE LEEWARD
ISLANDS...AND ON TROPICAL STORM BILL...LOCATED ABOUT 820 MILES
WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS.
A LARGE AREA OF CLOUDINESS AND THUNDERSTORMS OVER THE SOUTHEASTERN
GULF OF MEXICO IS PRIMARILY ASSOCIATED WITH A TROPICAL WAVE
INTERACTING WITH A MID- TO UPPER-LEVEL TROUGH. THIS ACTIVITY HAS
BECOME A LITTLE MORE CONCENTRATED OVER THE SOUTHEASTERN GULF OF
MEXICO WHERE SURFACE PRESSURES ARE BEGINNING TO FALL. THERE ARE NO
SIGNS OF A SURFACE CIRCULATION AT THIS TIME AND ANY ADDITIONAL
DEVELOPMENT...IF ANY...SHOULD BE SLOW TO OCCUR. THIS SYSTEM SHOULD
MOVES TOWARD THE NORTHWEST OVER THE EASTERN GULF OF MEXICO ON
SUNDAY. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
PUBLIC ADVISORIES ON TROPICAL STORM ANA ARE ISSUED UNDER WMO HEADER
WTNT32 KNHC AND UNDER AWIPS HEADER MIATCPAT2. FORECAST/ADVISORIES
ARE ISSUED UNDER WMO HEADER WTNT22 KNHC AND UNDER AWIPS HEADER
MIATCMAT2.
PUBLIC ADVISORIES ON TROPICAL STORM BILL ARE ISSUED UNDER WMO
HEADER WTNT33 KNHC AND UNDER AWIPS HEADER MIATCPAT3.
FORECAST/ADVISORIES ARE ISSUED UNDER WMO HEADER WTNT23 KNHC AND
UNDER AWIPS HEADER MIATCMAT3.
$$
FORECASTER AVILA/KIMBERLAIN
If it will be the ghost of Hugo, why would it hit Savannah, Hugo, make landfall near Charleston. And also, note: Hugo made landfall on September 22. So why would its ghost come bac in less than nearly a month to his date of birth and his date of landfall??
There isn't a single fully trained met left on the site, except for Dr. Masters of course. The couple we had have fled for higher waters. We have 1 recommended by Dr. Masters met(weather456), and 1 quasi-met, and 3000 amateur mets with a handful being presently studying fully trained mets.
Not much of a secret now, is it?
Wise words backed up by evidence...
If you had read the full conversation I was talking about mets on tv.
StormW's a met too.
so as sgt. friday would say...just the facts, please.
The winds do get that strong over the tropics.. I have seen jet streams over 100 kts over the caribbean islands chain and going out into the atlantic
Nope.
Rapid intensification, upper level low, and some weakest in the ridge might help steer it towards the trough more.
Who?
Hey Ike,
This late start has caught many off guard... let's hope that the storms don't make a trek toward us!
We all discussed, Masters included, that homegrown systems might rule this year in light of El Nino. Might this be one of them?
Can you please explain what that mean?
There have been strong storms that have been known to break through ridges.
The one in the SE GOM will be moving in to us tomorrow. Looks better on satellite this evening. I wouldn't rule out a TD to a weak TS with it.
WTNT32 KNHC 152331
TCPAT2
BULLETIN
TROPICAL STORM ANA INTERMEDIATE ADVISORY NUMBER 15A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
800 PM AST SAT AUG 15 2009
...ANA RACING WESTWARD WITH LITTLE CHANGE IN STRENGTH...
A TROPICAL STORM WATCH IS IN EFFECT FOR ST. MAARTEN...SABA...AND ST.
EUSTATIUS. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM
CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN
36 HOURS.
INTERESTS ELSEWHERE IN THE LEEWARD ISLANDS...THE VIRGIN
ISLANDS...AND PUERTO RICO SHOULD MONITOR THE PROGRESS OF ANA.
ADDITIONAL WATCHES AND WARNINGS MAY BE REQUIRED FOR PORTIONS OF
THESE AREAS TONIGHT AND SUNDAY.
FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA
OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR NATIONAL METEOROLOGICAL SERVICE.
AT 800 PM AST...0000 UTC...THE CENTER OF TROPICAL STORM ANA WAS
LOCATED NEAR LATITUDE 14.4 NORTH...LONGITUDE 50.4 WEST OR ABOUT
730 MILES...1180 KM...EAST-SOUTHEAST OF THE LEEWARD ISLANDS.
ANA IS MOVING TOWARD THE WEST NEAR 17 MPH...28 KM/HR. A TURN TOWARD
THE WEST-NORTHWEST IS EXPECTED DURING THE NEXT COUPLE OF DAYS.
THIS MOTION COULD BRING THE CENTER OF ANA NEAR THE LEEWARD ISLANDS
ON MONDAY.
MAXIMUM SUSTAINED WINDS REMAIN NEAR 40 MPH...65 KM/HR...WITH HIGHER
GUSTS. SOME SLOW STRENGTHENING IS POSSIBLE DURING THE NEXT
48 HOURS.
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM
FROM THE CENTER.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB...29.65 INCHES.
...SUMMARY OF 800 PM AST INFORMATION...
LOCATION...14.4N 50.4W
MAXIMUM SUSTAINED WINDS...40 MPH
PRESENT MOVEMENT...WEST OR 270 DEGREES AT 17 MPH
MINIMUM CENTRAL PRESSURE...1004 MB
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM AST.
$$
FORECASTER AVILA
No actually he isn't.
Pretty decent probability.
I am a long time lurker on this blog and do NOT post hardly at all, I have to agree, I do the same thing! At the same time taking the necessary precautions for safety first.
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