TD 2 nearly dead; African disturbance 90L gathering strength

By: Dr. Jeff Masters , 2:38 PM GMT on August 13, 2009

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Tropical Depression Two is near death, but is still worth watching. The dry, Saharan air to the north and west of the depression, combined with moderately high levels of wind shear of 15 - 20 knots, have almost completely destroyed all of TD 2's heavy thunderstorms. Satellite loops of the storm show a well-formed circulation, but almost no heavy thunderstorm activity.

Wind shear over TD 2 is expected to remain in the modereate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C three days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that TD 2 will not be able to intensify quickly, and some of the models indicate the TD 2 may get destroyed in the next day or two. However, several models still predict TD 2 will become a tropical storm. The HWRF model predicts TD 2 will become a hurricane five days from now, but this seems unlikely given the dry air and relatively high wind shear affecting the storm.


Figure 1. Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

African tropical wave 90L
A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.

I'll have an update Friday morning.

Jeff Masters

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2376. Chiggy007 9:14 PM CDT on August 13, 2009
HAHA, is that what taught you
Well said
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Quoting weatherblog:


Are you talking to me? There's such a thing called the quote button.

That requires some scripting. Some folks might have it turned off intentionally...or visiting from a smart phone with scripts disabled.
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Quoting PSLHokie:


... things that can't possibly be predicted....

uggg....

Where do you go to find those things?
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I have fallen into the blog of banned, cloned, related, definitely trolls, and who know what other characters, and I'm all by myself here...
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PSLhokie...read a book or take some classes. You might learn a little on here but there are too many non-mets to take what you read on here seriously. Maybe you know which ones are and arent and can have converstations with them.
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90l is going to have a good DMAX with all that divergence and outflow the convection will help it tighten up and help it get going...The models seem to think that the bermuda high eventually wins out as many of them turn the storm west at the end of their runs
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2380. KEEPEROFTHEGATE (Mod)
Quoting duprk452:


Caicos Retired Sailor.. i've always wanted to visit the turks and caicos when is the best time of year to visit?
anytime after nov 30 is good

lol
Member Since: July 15, 2006 Posts: 175 Comments: 54852
Quoting Hhunter:


A) PSLhokie is an idiot
b) PSLhokie is just not a patient person
c) PSLhokie needs some lythium
d) PSLhokie wants us to all think he knows his stuff in is thus better than all of us mere mortals.



all of the above
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Quoting Chiggy007:
Some people on here make me LAUGH - probably didn't even complete high school..
Anyway, all the panic about where 90L (for God's sake it's not even a depression yet) will eventually hitreally ticks me off..
Hey, I made it to second semester of my 8th grade year, buddy, so lay off. Besides, high school is overrated!
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Quoting duprk452:


Caicos Retired Sailor.. i've always wanted to visit the turks and caicos when is the best time of year to visit?


Only recommendation I would have is to avoid July, August, & September.

CRS
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HAHA, is that what taught you in weather school - stick your neck out and forecast the weather!
I am all for educated guesses and you have to agree with me that lot of people on here are not that educated when it comes to metereology - they've probably learned a few things from watching the TWC...!
IF you have formally studied weather than obviously this wasn't targeted to you...so YOU CHILL mate lol... PEACE!
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Quoting weatherblog:


I'm stating an opinion. If you don't like that then you're in the wrong place.
As i said earlier. this person is clueless
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2373. Hhunter
Quoting PSLHokie:


Holy crap...this is a weather blog, not a guess random events blog.... do you want us to predict the storm surge for the 3rd named storm this year too? Maybe we can "forcast" the tracks for the 2011 storm season.

Any more ridiculus polls?

How about using some real science for prediction? I tune in here to get a better understanding about how different weather patterns interact with tropical systems. I dont come here to create gossip and "fun" guessing games about things that can't possibly be predicted....

uggg....


A) PSLhokie is an idiot
b) PSLhokie is just not a patient person
c) PSLhokie needs some lythium
d) PSLhokie wants us to all think he knows his stuff in is thus better than all of us mere mortals.

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I hit the quote button. evedently i did not take. but yes i am talking to you.
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Quoting Chiggy007:
WEATHERBLOG: Stop talking on absolutes! None of us know where 90L is going and you don't know sqaut mate


I'm stating an opinion. If you don't like that then you're in the wrong place.
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Quoting DM21Altestic:
so, Biloxi and Katrina are married?

After seeing next post...my own post needed to go.
Wasn't that bad, mind you, just not tasteful in the context of the next post by DM...
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Right now, no one know where 90L is going. It is all a guessing game based on the latest models. To claim absolute, show ignorance of weather. I been through enough storms to know that 2 weeks out, the models, troughs, ect. can and will change.
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Quoting Chiggy007:
Some people on here make me LAUGH - probably didn't even complete high school..
Anyway, all the panic about where 90L (for God's sake it's not even a depression yet) will eventually hitreally ticks me off..

Maybe you are the one still in high school. I got a lot of weather experience and there is nothing wrong with trying to do a long range forecast...if you are wrong you are wrong but you can learn from it. How do you think we will ever get better or develop the capabilities to make long range forecasts? You stick your neck out, make a call and see what does and doesnt pan out. Chill out.
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WEATHERBLOG: Stop talking on absolutes! None of us know where 90L is going and you don't know sqaut mate
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And where did you guesstimation come from?
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Quoting Skyepony:


NGPI is doing the best for intensity on TD2 at the moment. It's in the speghetti models I linked you to. Colostate doesn't allow us to directly link the models so you will have to check the link I left & look under early track models if you want to see it's latest forcast. 45kts in 120kts. It doesn't strengthen 90L but maybe 5kts over the next 5days..
then we will consider this the outlier right?
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2361. KEEPEROFTHEGATE (Mod)
Quoting JLPR:


yep I am watching this one very closely since the GFS has been persistent in passing it close to my north, south or over me =S

But if the GFS is correct we should have TD3 soon
with everything isee and all info i have read sat imagest and other sources i am thinking 48 hrs from now which will be approaching 11 pm sat night for first advs. on td 03l
Member Since: July 15, 2006 Posts: 175 Comments: 54852
Quoting DM21Altestic:
so, Biloxi and Katrina are married?
no big bro and little sis
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Quoting CaicosRetiredSailor:


...not from the DR, but from Turks & Caicos
We have had a wonderful afternoon... full overcast, so I got yard work done, being kept cool by the breeze.

Incredible & beautiful deep blood red sunset, and not a drop of rain yet. The barometer has been rock steady all day at about 1018, some gusts up to 30 mph this eve but still from the SE as usual.

CRS


Caicos Retired Sailor.. i've always wanted to visit the turks and caicos when is the best time of year to visit?
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Some people on here make me LAUGH - probably didn't even complete high school..
Anyway, all the panic about where 90L (for God's sake it's not even a depression yet) will eventually hitreally ticks me off..
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Quoting FLHurricaneChaser:
Folks this is not going to be a Gulf storm. Lesser Antilles, Florida, and East Coast need to be watching this.


Yup.
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2356. DVG
If I remember correctly, it was the CMC predicting something Haiti Cuba area. Look at the water vapor tonight. Bastadi's video today also mentioned the wave leaning as an indication something was afoot. He didn't say one would, just something to watch.
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Quoting atmoaggie:

I could tell you two were related. Yer handles look a lot alike.
He's taken good care of me and so many others through many a storm. Knows what he's talking about
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2353. Hhunter
i think this is a big problem for central gulf states maybe uppper mid texas...it will be a freaking typical gulf monster as of late...
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Quoting weatherblog:


Sorry for the delay. I think since waters are very warm in the Bahamas it could be a major hurricane, unfortunately.
no problem, and i just want to see what it is like. ive been through a couple storms because ive lived in coral springs since 94, but never really took a direct impact. wilma was bad but it was only a cat 1 so i have mixed emotions. do the long term models show it hitting florida or missing it? i know some dont go that far from now but what about the ones who do? thank you so much in advance, i really appreciate it
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Quoting PSLHokie:


Holy crap...this is a weather blog, not a guess random events blog.... do you want us to predict the storm surge for the 3rd named storm this year too? Maybe we can "forcast" the tracks for the 2011 storm season.

Any more ridiculus polls?

How about using some real science for prediction? I tune in here to get a better understanding about how different weather patterns interact with tropical systems. I dont come here to create gossip and "fun" guessing games about things that can't possibly be predicted....

uggg....

Lay off it. I don't really like the polls either, but there is nothing else to do but wait for the model runs and look at the past week of synoptics. Not much else to do at the moment. And, no, watching the wave go through d-min isn't worth watching constantly, either.
This isn't nado predicting when the wall cloud is already up, this is TCs when there isn't anything there but a wave 3k+ miles from any land in front of it.
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2350. Skyepony (Mod)
Quoting kingzfan104:
regular english please. im not really in on meteorology lingo. which is the best wind forecast model?


NGPI is doing the best for intensity on TD2 at the moment. It's in the speghetti models I linked you to. Colostate doesn't allow us to directly link the models so you will have to check the link I left & look under early track models if you want to see it's latest forcast. 45kts in 120kts. It doesn't strengthen 90L but maybe 5kts over the next 5days..
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Quoting Tazmanian:
guys dont for get we have old TD 2 out there so we have too put up with TD 2 be for 90L all so TD 2 is trying too make a come back its trying to find lower shear

yep you never know maybe at peak of D-MAX ex-TD2 might be the verge of being re-born as a TD
shear is under 15kts and decreasing
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Quoting Hhunter:
anyone seen camin islander on her lately? I have always enjoyed his posts.
He was on earlier today.
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dont have to. i am not a wishcaster.
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Quoting kingzfan104:
ya, i wish i could see them a little more expanded though. i want to know whther it will go north of puerto rico and then going into se florida or going into the aribbean and going from there. which do you think happens?

I dont know...it all depends on the position and how strong the trough is moving across Conus at that time. If the Trough, front is all the way to the east coast then the storm will get pushed norhward. If it is lagging back in the Rockies still, then the Gulf is in trouble. Also depends on the amplitude.
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2345. JLPR
Quoting KEEPEROFTHEGATE:
yep right on time convection should continue to expand from 11 pm till about 4 am edt wane a little during the day tomorrow and tomorrow night then the 2nd convective cycle commences sat afternoon with strong organization sat night and named after that


yep I am watching this one very closely since the GFS has been persistent in passing it close to my north, south or over me =S

But if the GFS is correct we should have TD3 soon
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Quoting CaicosRetiredSailor:


... beautiful deep blood red sunset,...

CRS

Red skies at night ...
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2343. Hhunter
anyone seen camin islander on her lately? I have always enjoyed his posts.
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Big brother ,Little sister
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Quoting jlp09550:


Proof?


At least a reasoning we can follow...
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Quoting BILOXISAINT2:
Clueless


About what? I don't see you contributing anything...
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2339. lennit
did anyone see the 00run of the CMC last nite.. it showed 90L getting pulled to the NW at 8 days then moving back West toward FL in 9-10 frame and trof axis is over the MidWest
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Quoting HurricaneKyle:


23 did you listen to the .B.B. show? Pretty interesting. StormW and Bob both sounded concerned about 90L. What are your thoughts on this system?


Concerned as in how?
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Quoting Tazmanian:



lol too funny


Holy crap...this is a weather blog, not a guess random events blog.... do you want us to predict the storm surge for the 3rd named storm this year too? Maybe we can "forcast" the tracks for the 2011 storm season.

Any more ridiculus polls?

How about using some real science for prediction? I tune in here to get a better understanding about how different weather patterns interact with tropical systems. I dont come here to create gossip and "fun" guessing games about things that can't possibly be predicted....

uggg....
Member Since: Posts: Comments:

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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.