African tropical wave 99L slowly organizing

By: Dr. Jeff Masters , 1:26 PM GMT on July 31, 2012

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A tropical wave (Invest 99L) near 9°N 41°W, halfway between the Lesser Antilles Islands and the coast of Africa, has the potential to develop into a tropical depression later this week as it moves westward at 10 - 15 mph. Visible satellite loops show that the disturbance now has a moderate amount of poorly-organized heavy thunderstorms that continue to slowly increase in intensity and areal coverage. There is no surface circulation, but some counter-clockwise rotation of the large-scale cloud pattern is evident. Water vapor satellite loops show that 99L has a reasonably moist environment. The latest Saharan air layer analysis shows that the dry air from the Sahara lies to the north of 99L and is currently not affecting the storm. WInd shear over the disturbance is a light 5 - 10 knots, and ocean temperatures are 28°C, (82°F) which is well above the 26.5°C (80°F) threshold typically needed to allow formation of a tropical depression.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
Wind shear is expected to remain light through Friday, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. However, a band of high wind shear of 20 - 40 knots associated with the subtropical jet stream lies just to the north of 99L, and it would not be a surprise to see 99L experience some higher shear conditions than are currently forecast. The farther north 99L gets, the higher the shear it will experience, and the SHIPS model is predicting shear in the moderate range, 10 - 20 knots, for Saturday - Sunday, as the storm works its way to 15°N. The disturbance is at 9°N, which is close enough to the Equator that the storm will have some difficultly getting spinning. Most of the models are showing some slow development of 99L. There are some major differences in the predicted forward speed of 99L, with the ECMWF and UKMET models predicting the storm will reach the Lesser Antilles on Friday, and the GFS predicting a later arrival, on Saturday. At 8 am Tuesday, NHC gave 99L a 20% chance of developing into a tropical depression by Thursday morning. I expect the storm will begin having trouble with tendrils of dry air reaching down from the north at times this week, but give 99L a 50% chance of eventually developing into Tropical Storm Ernesto sometime in the next ten days. Residents and visitors to the Lesser Antilles Islands should anticipate heavy rains and strong winds from 99L beginning to affect the islands as early as Friday morning. The long-range fate of 99L next week is uncertain. A track west to west-northwest through the Caribbean, or to the northwest towards the U.S. East Coast are both possible. The storm is less likely to survive if it heads northwest towards the U.S.

Extreme heat in the Central U.S.
The withering heat in America's heartland continued on Monday, with high temperatures of 112° recorded in Winfield, Kansas and Searcy, Arkansas. Little Rock, Arkansas hit 111°, their 3rd hottest temperature ever record, behind the all time record of 114° set just last year on August 3, and the 112° reading of 7/31/1986. Wichita and Coffeyville in Kansas both hit 111° Monday, and in Oklahoma, Enid, Tulsa Jones Airport, and Chandler all topped out at 111°. Carr Creek, Missouri hit 110°, the hottest temperature measured in the state so far this year. Highs temperatures Tuesday and Wednesday in this region could reach 110° again, as the most extreme heat this week will stay focused over Oklahoma and surrounding states.

Jeff Masters

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Quoting StormTracker2K:


Damm! SOI is falling fast. Hey TA13 you see this. You like to bust your balls all the time but I always love your input on here.


He likes to what??
Member Since: July 15, 2006 Posts: 17 Comments: 10160
Saola is about to hit Taiwan hard. Hopefully it will not strengthen quickly before landfall like the last one did.

Member Since: July 15, 2006 Posts: 17 Comments: 10160
Fun Trivia :)

In 1969, a famous meteorologist added his daughter's name to the name list for that hurricane season as a graduation gift. He had no way of knowing at the time that the hurricane that would take his daughter's name, Camille, would become one of the most powerful and destructive hurricanes to ever hit the United States. Can you name that famous meteorologist?
Member Since: August 1, 2011 Posts: 28 Comments: 7913
Quoting RussianWinter:


Lol, the only person I can treat as a woman around here is that mother from texas. Everyone else here is a Sir.
You mean the one that always references "here" when she describes the weather? TX is a BIG state.
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Quoting BDAwx:


India has about 1.2 billion people, the world is about 7billion., by my calculations that is about 17% of the world. So 650million, about half of India, is 8.5% of the world - close enough to 10% or one tenth.
..imagine..having 17% of the worlds population in one country..must be living wall to wall there, after all..its not big like the USA is in area
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Quoting Waltanater:

is it a...dude?! LOL


In the English language, many things have no gender. It is a thing.
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Quoting LargoFl:
just wanted to mention what i heard today on the lush limbaugh show...he said.one tenth of ALL humanity..is without electricity today in india,650 million..now regardless of him....how much of India's population in total..hmmm how do i put this...the population of India..is how much of the total of humanity anyway?..geez..one half?


Why in the world are you listening to that garbage?

Anyway, India has roughly 1.2 billion. That'd put them at about 17% of the global population. Meaning that his # is pretty close... between 9-10% of the worlds population was/is involved in the India power outage today.

Edit: Saw post 576 answered your question. Sorry for the double answer
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Quoting MississippiWx:
SOI values from the past 4 days:

28 Jul 2012 1013.14 1014.00 -11.14
29 Jul 2012 1012.63 1014.50 -17.36
30 Jul 2012 1012.33 1014.60 -19.82
31 Jul 2012 1011.09 1014.60 -27.45


Damm! SOI is falling fast. Hey TA13 you see this. You know I like to bust your balls all the time but I always love your input on here.
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Well...as far as blogger gender...we have had "pretender trolls" in the past...so it can get a bit tricky :)
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Quoting CaribBoy:
I'm feeling disappointed 99L won't bring anything to the Northern Leewards if it goes that far south..


Is early to say that
Member Since: June 20, 2012 Posts: 0 Comments: 2150
Quoting MississippiWx:
Mesoscale Convective System. A complex of thunderstorms which becomes organized on a scale larger than the individual thunderstorms, and normally persists for several hours or more. MCSs may be round or linear in shape, and include systems such as tropical cyclones, squall lines, and Mesoscale Convective Complexes (MCCs) (among others). MCS often is used to describe a cluster of thunderstorms that does not satisfy the size, shape, or duration criteria of an Mesoscale Convective Complex.

..just LOOK..at the total area it includes..a monster sized storm
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Instead of he she he/she....hows bout the pronoun it.

Perfectly neutral.

Bad idea right? ;)
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?


is it a...dude?! LOL
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Quoting RussianWinter:


It's called a cloud. LOL.
LOL
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?


uh..storm?! LOL
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Bunch of comedians today, huh! :)
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Quoting 1928PalmBeach:
Guys and Gals,

A brand new blogger but a long-time weather buff and long time reader of this blog. Its very interesting to see how much prediction can be made long-term for what is really an unpredictable event. The long-term prediction of a tropical disturbance many days ahead of time. I liken a tropical system to a spinning top with many influences that change over time. Prediction usually needs many stable factors to make it accurate. Therefore, most of the conclusions I have ever read on this blog are usually wrong when it comes to where a storm will be 7-10 days from now. That being said I guess it is fun to speculate but I believe tropical systems are subject to chance and our very dynamic atmosphere. It's amazing what the models are able to do given the parameters they have to work within.
..and welcome to the blog
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Quoting CaribBoy:
I'm feeling disappointed 99L won't bring anything to the Northern Leewards if it goes that far south..


99L is a large system. If it stays anything like it is now or gets stronger, you most likely will get a good deal of tropical moisture/rains.
Member Since: July 15, 2006 Posts: 17 Comments: 10160
Kman, I'd keep an eye on this 99L, taking southern route, and you know how these things work...
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I'm feeling disappointed 99L won't bring anything to the Northern Leewards if it goes that far south..
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SOI values from the past 4 days:

28 Jul 2012 1013.14 1014.00 -11.14
29 Jul 2012 1012.63 1014.50 -17.36
30 Jul 2012 1012.33 1014.60 -19.82
31 Jul 2012 1011.09 1014.60 -27.45
Member Since: July 15, 2006 Posts: 17 Comments: 10160
Quoting JeffM:
Thanks for the analysis Kman!


:-)
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THANK YOU
Admin
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Quoting Stormchaser2007:


Mesoscale Convective System.


MCS? There's a pill for that now I heard.
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look it! look it!



hopefully something can build behind this lone cell which looks to take off shortly...

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Guys and Gals,

A brand new blogger but a long-time weather buff and long time reader of this blog. Its very interesting to see how much prediction can be made long-term for what is really an unpredictable event. The long-term prediction of a tropical disturbance many days ahead of time. I liken a tropical system to a spinning top with many influences that change over time. Prediction usually needs many stable factors to make it accurate. Therefore, most of the conclusions I have ever read on this blog are usually wrong when it comes to where a storm will be 7-10 days from now. That being said I guess it is fun to speculate but I believe tropical systems are subject to chance and our very dynamic atmosphere. It's amazing what the models are able to do given the parameters they have to work within.
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Quoting ncstorm:


I just gave up telling them..I guess we were supposed to end our posts with little hearts to let them know..

Yes. XD
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Quoting RitaEvac:


blob


Not bad. I think I'll use it.
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Quoting VR46L:


Well how would you like to be referred to as female all the time ..If you are unsure terms like you or they may be appropriate


I just gave up telling them..I guess we were supposed to end our posts with little hearts to let them know..
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Quoting VR46L:


Happened to me a few times too...Its almost as though , if you have an interest in weather you must be male ...


Sometimes the names can be misleading and confusing. I believe RitaEvac is male, and GeorgiaStormz are male. MrstormX is also male, but I always thought it was Mrs. StormX. There used to be a famous blogger here called atmoaggie and I always assumed (incorectly) he was female. I mean, I did have to call a guy Roberta once, but that was in restaurant San Francisco and another story.
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Quoting allancalderini:
you mean athomeinTX?


Yes, sir.
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Quoting HurricaneFetish:


No te me precipites de esa manera; mas bien para el jueves, diria yo, =).

Speak English, Janiel.
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?



blob
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583. JeffM
Thanks for the analysis Kman!
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Quoting HurricaneFetish:


No te me precipites de esa manera; mas bien para el jueves, diria yo, =).


whut?
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Quoting RussianWinter:


Lol, the only person I can treat as a woman around here is that mother from texas. Everyone else here is a Sir.
you mean athomeinTX?
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580. VR46L
Quoting RussianWinter:


Well what do you expect us to do?

Write he/she and him/her?


Well how would you like to be referred to as female all the time ..If you are unsure terms like you or they may be appropriate
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NHC didn't gave anything to area south of CV islands. That is because there is no model support.
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Quoting HurricaneFetish:


No te me precipites de esa manera; mas bien para el jueves, diria yo, =).


Bueno si, El Centro Nacional de huracanes de Miami ha estado muy conservativo ultimamente
Member Since: June 20, 2012 Posts: 0 Comments: 2150
Mesoscale Convective System. A complex of thunderstorms which becomes organized on a scale larger than the individual thunderstorms, and normally persists for several hours or more. MCSs may be round or linear in shape, and include systems such as tropical cyclones, squall lines, and Mesoscale Convective Complexes (MCCs) (among others). MCS often is used to describe a cluster of thunderstorms that does not satisfy the size, shape, or duration criteria of an Mesoscale Convective Complex.

Member Since: July 15, 2006 Posts: 17 Comments: 10160
576. BDAwx
Quoting LargoFl:
just wanted to mention what i heard today on the lush limbaugh show...he said.one tenth of ALL humanity..is without electricity today in india,650 million..now regardless of him....how much of India's population in total..hmmm how do i put this...the population of India..is how much of the total of humanity anyway?..geez..one half?


India has about 1.2 billion people, the world is about 7billion., by my calculations that is about 17% of the world. So 650million, about half of India, is 8.5% of the world - close enough to 10% or one tenth.
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?

Meridionalblob!!
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?

that is the area that is suppose to organize and become something near north eastern coast?
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?



Mesoscale Convective System.
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Quoting VR46L:


Happened to me a few times too...Its almost as though , if you have an interest in weather you must be male ...


Well what do you expect us to do?

Write he/she and him/her?
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.