Tropical Depression Four dusts the Cape Verdes; new threat approaching the Caribbean

By: Dr. Jeff Masters , 8:57 PM GMT on August 22, 2006

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Tropical Depression Four has increased its organization and is close to tropical storm status. It has made what is likely to be its closest pass to any land area--a brush of the Cape Verde Islands off the coast of Africa. The storm is moving towards the west-northwest away from these islands today, towards the open Atlantic. Mindelo reported sustained winds as high as 27 mph today, but no rain--just widespread dust. Other than pulling a lot of dust over these islands, the effect of the storm was minimal. The storm will provide a good case study for the NASA African Monsoon Multidisciplinary Analyses Project, which has several weather research aircraft based in the Cape Verdes Islands right now. The project aims to examine the formation and evolution of tropical hurricanes in the eastern and central Atlantic and their impact on the U.S. east coast, and the composition and structure of the Saharan Air Layer, and whether aerosols affect cloud precipitation and influence cyclone development.

TD Four is in a moderately favorable environment for intensification, and should be a tropical storm by morning. Wind shear is a low 5-10 knots. I expect this will be a Category 1 hurricane by Sunday, but it should stay far away from land. All of the models now have the storm recurving northwards well east of Bermuda early next week, as a trough of low pressure picks up the storm.

Figure 1. Visible satellite image from 2:30pm EDT Tue Aug 22 2006. TD Four is on the right of the image, just off the coast of Africa, and tropical disturbance 97L is in the left side of the image. A long line of cumulus clouds and thunderstorms nearly connects the two systems. Image credit: Navy Research Lab.

New threat approaching the Lesser Antilles
A tropical wave near 10N 47W has developed some rotation at mid levels, and is a threat to develop into a tropical depression later this week. NHC has assigned this disturbance the name "Invest 97L", and has tentatively tasked the Hurricane Hunters to investigate it on Thursday afternoon. There have been some intermittent bursts of heavy thunderstorm activity this afternoon near the center of circulation, but the cloud pattern is very disorganized at present. Wind shear is about 10-15 knots, the waters underneath are warm, and the wind shear is forecast to remain low for the next week along the system's path. The main impediment to development in the next two days will be the large area of dry air and Saharan dust to the wave's north. The system should move through the Lesser Antilles Islands on Thursday. The GFS and NOGAPS models hint at development in the Central Caribbean by Saturday, and a possible threat to Jamaica, Cuba, and Hispanolia by Sunday. We'll have to watch this system carefully, it has the potential to be trouble.


Figure 2. Preliminary model tracks for disturbance 97L approaching the Lesser Antilles Islands.

An area of thunderstorms in the western Caribbean near Cuba is drifting northwestwards into the Gulf of Mexico. Wind shear is a high 20 knots over this area, and upper level winds are not favorable for development.

I'll have an update in the morning.

Jeff Masters

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1109. Cavin Rawlins
2:18 PM GMT on August 23, 2006
A new blog is up
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1108. whirlwind
1:56 PM GMT on August 23, 2006
cheeeezz usssss chrrisssttttt....

gulfscotsman...can we be a little more compasonate here??!!!
everyone wants a damn storm already, we are tired, irritated, upset......
can you show some positive attitude already...at least maybe for 97L????


;D
1107. miamihurricane12
1:56 PM GMT on August 23, 2006
i played against pace last year, and marrero hit a home run and walked around the bases so we hit the next guy on purpose and he rushed the mound....and by the way marrero is on steroids
1106. Oreodog
1:55 PM GMT on August 23, 2006
Gimme an "E"
1105. LyonOfLongBeach
1:55 PM GMT on August 23, 2006
Debbie is definately pining for the fjords. Let's see how long it takes 97L to flare up and die as well.
So far this has been like the Gigli of tropical seasons, sheeeeeeeeeesh!
1104. 21N71W
1:55 PM GMT on August 23, 2006
new blog
Member Since: August 1, 2006 Posts: 0 Comments: 180
1103. littlefish
1:54 PM GMT on August 23, 2006
Bummer, the 97L coc jumped/reformed forward (west) and now is too close to S America. It'll have to turn quick.
1100. fla1963
1:52 PM GMT on August 23, 2006
GulfScotsman Where Where????
1099. nash28
1:51 PM GMT on August 23, 2006
Yep, I see Gulf is in rare form today.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
1097. Tazmanian
1:49 PM GMT on August 23, 2006
on the navy site 45kt 1000mb it all most a hurricane
Member Since: May 21, 2006 Posts: 5091 Comments: 114965
1095. TheRingo
1:41 PM GMT on August 23, 2006
would it be possible if debbie tries to skirt south of the dust?
1094. Tazmanian
1:41 PM GMT on August 23, 2006
Debby is a little stronger now 45kt 1000mb
Member Since: May 21, 2006 Posts: 5091 Comments: 114965
1093. vortextrance
1:39 PM GMT on August 23, 2006
have a good day gamma, I haven't seen you on here much this year.
Member Since: October 5, 2005 Posts: 0 Comments: 700
1092. Canesinlowplaces
1:39 PM GMT on August 23, 2006
I have to agree with the Scotsman. I don't see Debby doing all that much. It looks like it's got some shear - and then there's that huge area of dry air. It's just a different version of the Chris story. Believe me. It's written in stone - not. Probably because I just made this prediction, it'll turn into a cat5.
Member Since: July 12, 2006 Posts: 0 Comments: 133
1091. vortextrance
1:38 PM GMT on August 23, 2006
Posted By: GulfScotsman at 1:35 PM GMT on August 23, 2006.
you can BELIEVE anything you want... but this is NOT going to become a Hurricane!!! sorry!!!


I agree Gulf, I would be real surprised to see a hurricane, but Debby is not weakening right now.
Member Since: October 5, 2005 Posts: 0 Comments: 700
1090. ricderr
1:37 PM GMT on August 23, 2006
you can BELIEVE anything you want... but this is NOT going to become a Hurricane!!! sorry!!!
WHSSSSHHHHH....WHSSSSSHHHHHHH....hears the winds of hurricane debbie in the atlantic

call me the official Hdebbie chearleader...give me a D!!
Member Since: June 27, 2006 Posts: 673 Comments: 21585
1089. Tazmanian
1:36 PM GMT on August 23, 2006
i think we sould this trun to 97L
Member Since: May 21, 2006 Posts: 5091 Comments: 114965
1088. seflagamma
1:36 PM GMT on August 23, 2006
Good morning everyone, Sure hope Dr Master's gets in an update soon, this blog is bloated!!!

everyone have a great day as we all keep an eye on the topics.
Gamma
Member Since: August 29, 2005 Posts: 298 Comments: 40894
1087. jandree22
1:35 PM GMT on August 23, 2006
...and to think just yesterday I was worried Debby would ruin my Keys vacation next week, shows what I know. oh well, guess I can't do more than just try to calm down and see how 97 develops
1085. Canesinlowplaces
1:32 PM GMT on August 23, 2006
Also, the biggest part of the convection over Debby seems to be centered just a little south of the coc.
Member Since: July 12, 2006 Posts: 0 Comments: 133
1084. kmanislander
1:30 PM GMT on August 23, 2006
off to work myself
catch u all later

Member Since: August 19, 2006 Posts: 0 Comments: 15813
1083. StormJunkie
1:28 PM GMT on August 23, 2006
Morning ya'll...

Looks like the big questions is still if Debbie will pick up enough strength to get turned N.

Also noticed it was interesting that the GFDL wanted to ramp 97 up pretty quickly and I think that is why it is showing the more nortehrly track.

Got to get to work, and it looks like I will be there a little late tonight :( Ya'll have a great day.

StormJunkie.com-Forecast models, imagery, marine data, wind data, preparedness info, storm video from WU bloggers, and much more.

Also check out the Quick Links page for fast and easy access to many of the best weather and tropical sites on the web.
Member Since: August 17, 2005 Posts: 26 Comments: 16420
1082. Canesinlowplaces
1:27 PM GMT on August 23, 2006
BTW, I was referencing the Debby RGB loop.
Member Since: July 12, 2006 Posts: 0 Comments: 133
1081. Cavin Rawlins
1:26 PM GMT on August 23, 2006
I agree, Debby is surrounded by dust and she seems to dont care.....

So much for dust...the next healthy wave to come in dust off Africa, has my take of development......
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1080. Canesinlowplaces
1:26 PM GMT on August 23, 2006
On the RGB loop, it looks like some thin whisps of mid/upper level clouds blowing off to the south - indication of shearing?
Member Since: July 12, 2006 Posts: 0 Comments: 133
1079. kmanislander
1:26 PM GMT on August 23, 2006
but Gilbert was only a TD. Before Wilma Gilbert held the recored for the most intense system ever in the ATL.
Just goes to show that two very different systems can have the same ultimate intensity levels at the same place further down the road
Member Since: August 19, 2006 Posts: 0 Comments: 15813
1078. floridafisherman
1:25 PM GMT on August 23, 2006
ty for all the info kman i thought it was ivan but i cant remember where every storm was at any particular time lol ty once again thats why i like this site because everyone is always pretty helpful for the most part
Member Since: August 28, 2005 Posts: 0 Comments: 551
1077. StormReadyinSFL
1:24 PM GMT on August 23, 2006
AVG is the best anti-virus out there. The trojans you guys are seeing are probably from a program that got downloaded. This program then creates the trojan under a different name everytime you boot your computer. NO anti-virus is designed to find a program. You need find the program that is creating the trojan. Sometimes you can find it by using MSconfig and see what programs are set to start everytime you boot the computer. Usually, the trojan producing program name will be something really wierd.
1076. fla1963
1:24 PM GMT on August 23, 2006
There? Where?
1075. nash28
1:24 PM GMT on August 23, 2006
Guys, don't overreact. It's not even a TD yet. I don't think anyone needs to be rushing for gas.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
1074. vortextrance
1:23 PM GMT on August 23, 2006
I would say Debbie is as strong as she has ever been. I am surprised that the large amount of dust to the west isn't bothering her more.
Member Since: October 5, 2005 Posts: 0 Comments: 700
1073. kmanislander
1:23 PM GMT on August 23, 2006
swfl

Ivan was a CAT 3 system at the current location of 97L
Member Since: August 19, 2006 Posts: 0 Comments: 15813
1072. msuwxman
1:23 PM GMT on August 23, 2006
There is a low level circulation there.
Member Since: August 9, 2006 Posts: 0 Comments: 150
1071. gbreezegirl
1:22 PM GMT on August 23, 2006
Please Ike, don't remind me. I saw that same thing this morning as well. Bad feeling in gut. Thing I may gas up this afternoon before the rush and rise in prices!
Member Since: September 7, 2005 Posts: 0 Comments: 274
1070. Cavin Rawlins
1:21 PM GMT on August 23, 2006
Debby is looking its best.....
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1069. ricderr
1:21 PM GMT on August 23, 2006
Gs...she's gonna be Hurricane Debbie..and all the sissies...i mean fishies..will bow down before her
Member Since: June 27, 2006 Posts: 673 Comments: 21585
1068. floridafisherman
1:20 PM GMT on August 23, 2006
gulf how can u say that debbie is weakening. i see it strengthening if anything
Member Since: August 28, 2005 Posts: 0 Comments: 551
1067. Cavin Rawlins
1:20 PM GMT on August 23, 2006
Posted By: Canesinlowplaces at 9:09 AM AST on August 23, 2006.
Thanks 456. So staying on the southern edge means more westerly movement - seems to me gfdl takes it too much north.


ULHs do not steer surface features....ULHs, only provide them with good conditions.

97L is more under the influence of a surface subtropical high and a more powerful high, with its ridge(edge) extending NW towards FL then back out to sea.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1066. Canesinlowplaces
1:19 PM GMT on August 23, 2006
The steering currents map also indicates that Debby will be in the Caribbean - so much for the steering currents maps. Although I guess these things aren't static, so you would have to have a steering currents forecast map.
Member Since: July 12, 2006 Posts: 0 Comments: 133
1065. SWFLdrob
1:19 PM GMT on August 23, 2006
Posted By: IKE at 8:08 AM CDT on August 23, 2006.
Ivan in 2004 was at the exact same coordinates as 97L is right now.

Wasn't Ivan already a hurricane when it was in the same position 97L is right now?
1063. KRL
1:17 PM GMT on August 23, 2006
Posted By: leftovers at 8:51 AM EDT on August 23, 2006.
I really dont see much out there that can ruin my week. Ike your the one who now uses Brighthouse broadband. Remember I warned you about viruses. Well yesterday my Norton anti virus which I am paid up for a yr detected another trojan that somehow slipped into the system. I asked a few experts what it was all about. My daughters boyfriend who is a computer installer said dont worry about it just dont use a credit card. I thought I would be protected when I bought the anti virus program I guess nothing is full proof. Be careful what you download.


Get SpySweeper. Its the best at keeping out the nasties.

http://www.webroot.com/consumer/products/spysweeper/

Try to get the older Version 4.5.9 Build 709. The new version 5 require heeps of memory for all the system protection functions it runs. The older version works great.
Member Since: July 31, 2006 Posts: 0 Comments: 231
1062. weatherbrat
1:17 PM GMT on August 23, 2006
In Pensacola....stayed home during Ivan...UGHhhh!!! I don't want to go through that again. "Debby" can do her thing and fizzle out. I'm more interested in what 97L is going to do. Four of the five models I looked at this morning seem to think 97L will be tracking into the Carribean and heading for the GOM. That doesn't give me a warm & fuzzy feeling. I'm just now getting my windows replaced from last years "Dennis". We'll all have to stay on our toes if 97L decides to rear it's ugly head!
1061. Tazmanian
1:17 PM GMT on August 23, 2006
send me mail send me mail from time to time ok
Member Since: May 21, 2006 Posts: 5091 Comments: 114965
1060. ricderr
1:17 PM GMT on August 23, 2006
gs..you sarcastic?.....i'd have never guessed...now let me go back and reread your posts in this new light
Member Since: June 27, 2006 Posts: 673 Comments: 21585
1059. kmanislander
1:16 PM GMT on August 23, 2006
florida

Ivan passed right over Grenada which is very far S
Member Since: August 19, 2006 Posts: 0 Comments: 15813

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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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