WunderBlog Archive » Category 6™

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

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

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

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

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

1001. Patrap
..Debbie to wind up ..near the Azores as alow swirling cloud deck..in 6 days....
ONE LITTLE POPCORN FART THUNDERSTORM SOUTH OF CUBA.
Taz,
Central Atlantic
97L Invest
Never thought I's become obsessed with the weather. I see I have alot to learn.

Steve
NOLA
A well-defined tropical wave located about 550 miles east of the
Windward Islands
is moving westward at 15 to 20 mph. Although
this system has changed little in organization overnight...it has
the potential to develop into a tropical depression during the
next day or two. Interests in the Lesser Antilles should closely
monitor the progress of this system.


is this the one could some post a phtot of 97L on her
1006. Patrap
..is out to go feed shrimp to da croakers & maybe hook a flounder or a speck..enjoy the day...b nice....
1007. ricderr
pat....day starts at 4:30..pt...the three s's..read the paper...eat breakfast..read and write emails....play with the weather..and when the admiral gets up in about a half hour...i'm at her bidding for the rest of the day
look like t-storm trying to start for 97L
1009. Patrap
..enjoy ..like I said..Im going fishing...have FEma rep coming around 9am..leaving him a note to call me on trailer door...hes gonna b the one to wait today...
97L

1011. ricderr
pat.....wonder who has more to lose...he gets paid no matter what...enjoy your day
ptrap good luck fishing lol i love catching specks but waters little warm here for them...snook and tarpon are biting good
good morning all

97L is starting to look like its getting its act together. This is the first time there has been any real convection to speak of near the LLC

It still has time to get to TD status before entering the E Caribbean and if it does that may be bad news for the NW Caribbean and beyond

Any system entering the basin at that low a lat tends to wind up in the NW Caribbean
Atlantic Summary
There is an upper level continental high over the U.S.A., that extends into the Western Atlantic, where an upper level low is situated north of the Bahamas, helping to generate some moisture over Florida and the North, and Central Bahamas.

A surface subtropical high is located 31N, 52W, creating ridging (the edge of the high), extending all the way across the Western Atlantic to Florida.

An Upper Level Low is located over Central Mexico, helping to draw/flow moisture inward from the Pacific Ocean, on the western side, and the Gulf on the Eastern side, resulting in a long stream of moisture stretching upward across the Gulf and NW Caribbean Sea, where numerous showers are seen along 82W between Cuba, and the Yucatan Peninsula.

Rainfall total across the area were as high as 40mm in 3hrs, in some spots, yesterday.

Another area of strong thunderstorms and showers is located in the Bay of Campeche, this morning. If it could remain over water, then something could form, as wind shear is only 10-15knots in the area.

A slowing moving frontal boundary is situated over the SE United States with a surface High Pressure area near Texas.

A tropical wave moving west south of Jamaica, another one moving west near the Windward Islands. The latter one is creating numerous showers across the Windward Islands and Trinidad and Tobago.

A Central Atlantic wave (97L) accompanied by an area of broad low pressure, located along 54W with little to moderate scattered showers. This low will be watch for development as it moves west.

The Atlantic Ocean is dominated by surface ridging at the surface by two highs and an Upper level High Pressure area east of the Islands.

The NW quadrant of the ULH and some SE flow extending from the ULL near the Bahamas is generating some High wind shear in the Atlantic, just north and east of the Islands.

Tropical Storm Debby is located 15.9N, 30.1W, in the open Atlantic. The tropical storm is moving WNW at 16mph. It is forecast to continue moving WNW around a ridge (mentioned earlier) then NW as the ridge is weakened by a Central Atlantic Upper Level trough.
1015. IKE
Posted By: kmanislander at 7:30 AM CDT on August 23, 2006.
good morning all

97L is starting to look like its getting its act together. This is the first time there has been any real convection to speak of near the LLC


I agree...convection does appear to be increasing.
1017. ricderr
gs.....remember..it's not the size of the bait..but the presentation
: IKE i seen the photo of 97L but oh is oh?
hi ike

I guess 97L will be the focus of attention today. Shear was high in the E Caribbean yesterday but I have not checked the forecast levels for tomorrow and beyond.

Do you know off hand what the forecast looks like ??
Atlantic
97L.INVEST
04L.DEBBY

East Pacific
10E.ILEANA
09E.HECTOR

Central Pacific
93C.INVEST
92C.INVEST
01C.IOKE

West Pacific
97W.INVEST
96W.INVEST
95W.INVEST
97L...definately more convection with a twist.
gotta get my java
only 7:40 here
bb soon
Agreed, focus should switch to 97L. Cape Verde is safely away and land is far far away, if at all.
Morning all
1025. nash28
97L could be TD5 today.
looks like shear is still high in e carib, 97L may not have time to get its act together
Looks like 97 is too close to SAmerica
this is why you do not want 07L in the gulf look

lol


now what add a eddy to that


lol


and add to that we got red hot sea temps
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.
1030. PBG00
Mornin everyone..
GFLD seems to take Invest 97L more NW, weird, but isnt this model fairly accurate?
GFLD seems to take Invest 97L more NW, weird, but isnt this model fairly accurate?
boy, the gfdl model for 97L sure is bullish!!!

if is to be believed, 93L will be Ernesto.....
1034. PBG00
The gfdl is one of the more reliable models..if another model makes that shift it will be something to watch.
the shear is forecast to weaken, we'll see how soon it does. i agree 97L is pretty close to S america.
Morning all.
Ernesto, come towards the se coast, and MAYBE you can churn the fishee's..... go westward Ernesto, you be a BAD BOY!!!!
I think the shortwave trough that is going to pick up Debbie is going to be a very close call....Debbie is now a compact system and may not feel the trough as much as it would of earlier as the massive system it was, secondly, it needs to really gain latitude if it does not make it to 25N in a few days, the trough I think will miss it and it will continue to the West, iif Debbie makes it to 25N and thr trough is there yeah I can see it moving NW.

My take on the computer models now is the GDFL has 97L moving NW? But most have it going West which means I think a stronger high? They are not in good agreement.
1040. ricderr
HMM...gs...does that mean you'll be minnow watching?
There looks to be some clockwise spinning right above 97l. Does that indicate a high? - if so, wouldn't that tend to keep 97l going more westerly as opposed to the gfdl?
1042. IKE
Posted By: leftovers at 7:51 AM CDT 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.


That's what I get...trojan viruses. I've got AVG.
Posted By: Canesinlowplaces at 9:00 AM AST on August 23, 2006.
There looks to be some clockwise spinning right above 97l. Does that indicate a high? - if so, wouldn't that tend to keep 97l going more westerly as opposed to the gfdl?


Its an Upper Level High, as long as 97L stay on the southern edge, it will have a good chance of becoming TD05, as early as Thursday.
the low lat for 97L is not necessarily a problem for it. Cesar came in over T&T in 1996 and was classified a TD @ 11.8N62.6W

Cesar went on to become a 80MPH hurricane that went ashore in Nicaragua
1046. IKE
Ivan in 2004 was at the exact same coordinates as 97L is right now.
so where is 97L going look like to me it going to make a run for thr gulf but where is the $100 ?
Thanks 456. So staying on the southern edge means more westerly movement - seems to me gfdl takes it too much north.
ike

you said it.Caymanians pay close attention to anything that low down as do Jamaicans. Gilbert and Ivan both started down there and gave both these places a good pasting. Lucky for Ja Ivan put on the brakes about 50 miles S and then walked around their S coast before paying us a visit
1051. ricderr
sorry gs..i was referring to your tropical discussion..and figured..with what you wrote..it must mean..that your emphasis would be on watching debbie.. :-)
" My daughters boyfriend who is a computer installer said dont worry about it just dont use a credit card."

no offense intended, but what an idiot! LOL

personally i wouldnt have a computer that i don't feel safe enough to use a credit card! LOL

i'd tell your daughters "boyfriend" he needs to get educated on internet security! ;)

if the gfdl is to be believed, we could have TD5 today?????
The steering currents map also indicates westerly movement for 97l.
i dont think 97l is too close to s. america if my memory serves me right wasnt ivan or one of those other strong storms also very close to s america before U.S. landfall? i may be wrong can someone help me?
cant wait for dr m update
Gilbert and Ivan did behave differently though although both came through the NW Caribbean in the end. Gilbert came up just below Puerto Rico and then turned W in response to a strong high N of the islands.

Ivan came in real low and then WNW through the central Caribbean. With Gilbert I thought we were out of the woods after seeing it head up towards PR but it still passed about 60 miles S of us. Luckily we did not get too much damage from it ( about 14 million)
IKE .... you got wundermail! LOL
florida

Ivan passed right over Grenada which is very far S
1060. ricderr
gs..you sarcastic?.....i'd have never guessed...now let me go back and reread your posts in this new light
send me mail send me mail from time to time ok
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!
1063. KRL
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.
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?
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.
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.
gulf how can u say that debbie is weakening. i see it strengthening if anything
1069. ricderr
Gs...she's gonna be Hurricane Debbie..and all the sissies...i mean fishies..will bow down before her
Debby is looking its best.....
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!
There is a low level circulation there.
swfl

Ivan was a CAT 3 system at the current location of 97L
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.
1075. nash28
Guys, don't overreact. It's not even a TD yet. I don't think anyone needs to be rushing for gas.
1076. fla1963
There? Where?
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.
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
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
On the RGB loop, it looks like some thin whisps of mid/upper level clouds blowing off to the south - indication of shearing?
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......
BTW, I was referencing the Debby RGB loop.
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.
off to work myself
catch u all later

Also, the biggest part of the convection over Debby seems to be centered just a little south of the coc.
...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
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
i think we sould this trun to 97L
1090. ricderr
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!!
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.
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.
have a good day gamma, I haven't seen you on here much this year.
Debby is a little stronger now 45kt 1000mb
would it be possible if debbie tries to skirt south of the dust?
on the navy site 45kt 1000mb it all most a hurricane
1099. nash28
Yep, I see Gulf is in rare form today.
1100. fla1963
GulfScotsman Where Where????
Thanks storm be ready in So Fl. I will look into it. Your So Fl baseball team Pace took it to my sons hschool team. We had you unfornately my son gave up a homer to Morerro who now plays for a Washington minor league team which ended up being the winning run. There are some great players on that team. Damn computer.
Bummer, the 97L coc jumped/reformed forward (west) and now is too close to S America. It'll have to turn quick.
1104. 21N71W
new blog
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!
1106. Oreodog
Gimme an "E"
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
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
A new blog is up