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 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: August 21, 2011 Posts: 0 Comments: 666
Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?



I think it's Hot Mess ;)
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?



MCS...Lol.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting Hoff511:


Does anyone think Ernesto will be an analog storm for Ernesto?
http://en.wikipedia.org/wiki/File:Ernesto_2006_tr ack.png
possible.
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Quoting Grothar:
I wonder if there is a meteorological term for a feature like this?



It's called a cloud. LOL.
Member Since: August 21, 2011 Posts: 0 Comments: 666
At 8:00 PM 50-60%
At 2:00 AM 80-90% (wednesday)
At 8:00 AM(wednesday) DEPRESION
Member Since: June 20, 2012 Posts: 0 Comments: 2164
I wonder if there is a meteorological term for a feature like this?

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561. VR46L
Quoting ncstorm:


I am not a he..I am a she..I have told this blog this many times and you guys keep calling me dude when addressing me..do I type in "male"


Happened to me a few times too...Its almost as though , if you have an interest in weather you must be male ...
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Ts Damrey will make landfall north of shanghai but it has a shot to make landfall over the city and with Saola in the way this is not good China already has problem with water and with these two in the way.
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Quoting Hoff511:
Does anyone think Ernesto will be an analog storm for Ernesto?


It's looking that way, but it'll probably be further west than Ernesto from back in '06.
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Member Since: July 15, 2006 Posts: 17 Comments: 10284


Does anyone think Ernesto will be an analog storm for Ernesto?
http://en.wikipedia.org/wiki/File:Ernesto_2006_tr ack.png
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Quoting allancalderini:
yeah I do the same but for example they are cases where I know is a women because of the pictures that they put I knew washi was women because of the photo of a girl anime.


Lol, the only person I can treat as a woman around here is that mother from texas. Everyone else here is a Sir.
Member Since: August 21, 2011 Posts: 0 Comments: 666
551. LOL. You make me laugh.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting LargoFl:
......see how low in latitude this is..i just dont see it making that right hand turn
you remember Charley developed at this low latitude and we'll we all know how that played out.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting RussianWinter:


Well women are a bit uncommon these days, so I assume that you're a man until you mention otherwise.
yeah I do the same but for example they are cases where I know is a women because of the pictures that they put I knew washi was women because of the photo of a girl anime.
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552. JLPR2
Quoting LargoFl:
..LOL..and its about time they started coloring in that blob by PR


So far I have gotten a bit over half an inch today from it. Pushed my July total over the average.

Actual month total 5.85
Normal month total 5.43
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting LargoFl:
..yes but the HIGH is blocking the way in..and what would PULL the whatever it becomes..northward instead of following the other waves west


the high is not blocking the Caribbean route
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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?
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western Caribbean...
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Quoting MississippiWx:


Wuuuuuut?
You're getting slower as you get older, MissWx ;)
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Quoting ncstorm:


sigh..


Just messing with you. :-)
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting ncstorm:


I am not a he..I am a she..I have told this blog this many times and you guys keep calling me dude when addressing me..do I type in "male"


you are a she?
i had no idea.
always thought you were a he
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Quoting MississippiWx:


Real-time data of what? No data supports a closed low anywhere.


Nothing is going to come out of a conversation with him. He's just trying to get attention.

Don't even bother.
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Quoting MississippiWx:


That explains the moodiness. :-O


sigh..
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540. JLPR2
Quoting Pocamocca:

Low ain't closed.


Yep, OSCAT shows that.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting ncstorm:


I guess women cant blog about weather for some reason..LOL..


There aren't any girls on the internet, that's a fact. :)
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Quoting TropicalAnalystwx13:

It's okay, I posted the first to post the text. :D


Wuuuuuut?
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting ncstorm:


I guess women cant blog about weather for some reason..LOL..


Well women are a bit uncommon these days, so I assume that you're a man until you mention otherwise.
Member Since: August 21, 2011 Posts: 0 Comments: 666
Quoting ncstorm:


I am not a he..I am a she..I have told this blog this many times and you guys keep calling me dude when addressing me..do I type in "male"


That explains the moodiness. :-O
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Nothing surprising on the TWO.

I'll stick with my 40% over the next 72 hours.
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Quoting reedzone:


Two things...

1. Wind shear is 5-10 knots, conditions are currently favorable under that wave..

2. Don't mention politics on here.


A WESTWARD-MOVING TROPICAL WAVE OVER THE CENTRAL CARIBBEAN IS
PRODUCING WIDESPREAD CLOUDINESS AND THUNDERSTORMS FROM HISPANIOLA
EASTWARD FOR SEVERAL HUNDRED MILES. UPPER-LEVEL WINDS ARE NOT
FAVORABLE FOR DEVELOPMENT...AND THIS SYSTEM HAS A LOW CHANCE...NEAR
0 PERCENT.
..OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS. HEAVY RAINS AND GUSTY WINDS ASSOCIATED WITH THIS WAVE WILL
SPREAD OVER HISPANIOLA...EASTERN CUBA...AND THE SOUTHEASTERN
BAHAMAS DURING THE NEXT DAY OR TWO.

Buen palomo, queriendo saber sin saber
Member Since: June 20, 2012 Posts: 0 Comments: 2164
Quoting JLPR2:


Orange! Ah, it's been too long since I saw that color. XD
..LOL..and its about time they started coloring in that blob by PR
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Well, my Firefox isn't working right today :\ I'm on Internet Explorer (yeah, I know...). And I see that NHC got 99L at 30% and that first wave at 0%. I am seeing that 99L is now favorable to go southern path instead of northern path.
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Quoting MississippiWx:


Too slow. :-p

It's okay, I posted the first to post the text. :D
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Quoting GTcooliebai:
The NHC broke out with some new crayons:

......see how low in latitude this is..i just dont see it making that right hand turn
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Quoting HurricaneFetish:


I go by real-time data obs, not by the misinformation of others.

interpretations are objective, not subjective.

Live & learn!


Real-time data of what? No data supports a closed low anywhere.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
He's up to 30%
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Quoting Pocamocca:

They refer to me as male to. LOL


I guess women cant blog about weather for some reason..LOL..
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522. JLPR2
Quoting LargoFl:


Orange! Ah, it's been too long since I saw that color. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting ncstorm:


I am not a he..I am a she..I have told this blog this many times and you guys keep calling me dude when addressing me..do I type in "male"
For 28 days a month you do.
I was wondering about those other 3 days.
.
.
.
j/k
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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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