African tropical wave 99L has potential to develop

By: Dr. Jeff Masters , 3:10 PM GMT on July 30, 2012

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The first African tropical wave of 2012 with a potential to develop is Invest 99L, located in the Eastern Atlantic near 9°N 36°W, midway between the Lesser Antilles Islands and the coast of Africa. Visible satellite loops show a large area of the surrounding atmosphere has a pronounced counter-clockwise spin, though there is no surface circulation. The disturbance's heavy thunderstorm activity is pretty sparse, but appears to be slowly increasing. Water vapor satellite loops show that 99L has a reasonably moist environment, and the latest Saharan air layer analysis shows that the dry air from the Sahara lies well to the north of 99L. 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 for the next five days, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. 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, with the storm reaching the Lesser Antilles Islands on Saturday, August 3. NHC gave 99L a 20% chance of developing into a tropical depression by Wednesday morning. I expect the storm will have trouble with dry air at times this week as it crosses the Atlantic, but I 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 night. The long-range fate of 99L is uncertain, but a trough of low pressure is expected to be present over the Eastern U.S. early next week, which would be capable of turning 99L more to the northwest.

Hot in the Central U.S.
The heat in America's heartland continued on Sunday, with Wichita, KS hitting 111°F, just 3° short of their all-time hottest temperature of 114° set on 8/12/1936. Other notable highs on Sunday:

111° Coffeyville, KS
111° Winfield, KS
110° Chanute, KS
110° Parsons, KS
109° Joplin, MO (all-time record is 115° on July 14, 1954)

The low temperature in Tulsa, Oklahoma this Monday morning dropped to only 88°F. This is the all-time warmest low temperature in the city since record keeping began in 1905. The previous record warmest minimum temperature was 87°F set on August 2, 2011 and July 16, 1980. The high in Tulsa Monday - Wednesday is expected to reach 110° - 111°, close to the city's all-time hottest temperature of 115° set on August 10, 1936.

Jeff Masters

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Quoting Grothar:


Here is a link for you.

Link


That's a cool link! It's weird how some years were insanely active and then nothing for a dozen years. Random? or is there a pattern?
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The CMC is the only model I see showing any kind of real development.


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1368. Grothar
I really don't want to get in the middle of anything, but what is a Chick Filet? I honestly never heard of it.
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Quoting Stormchaser121:
Models are beginning to show more of a westward path

If you mean more northerly, yes.
Member Since: July 6, 2010 Posts: 113 Comments: 31430
Models are beginning to show more of a westward path
Member Since: September 2, 2011 Posts: 0 Comments: 1143
1365. Grothar
Quoting Ameister12:


Geez what if one year would have that many storms.


Could you imagine the blog?
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1364. Grothar
Quoting Bluestorm5:


*Rolling on floor laughing* How the heck did you tracked hurricanes in the 1700s ;)


Here is a link for you.

Link
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Quoting spathy:


I just kilt it.
Sorry.
I will leave for the evening.
Nah, its ok, it is coming back to life.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting Astrometeor:
Hey everyone. I have now completely recovered from my wisdom teeth surgery last Wednesday. Like a lot of people on here, I am itching for a storm in the Atlantic. (stupid chiggers)

My birthday is coming up and I was thinking about asking my parents for a handheld anemometer. Does anyone have any suggestions on what to buy? Thanks in advance.


Ouch! My nephew is going through that also, I have been lucky, still got all mine. My brother though had the same problem as his kid. Still he has more hair than I do, too bad you don't get to choose the genes your parents give you (yet!). I have something called a Brunton Sherpa, which is a micro (you can put in your shirt pocket) weather station, including anemometer. Had if for years and it has never let me down, used it recently to measure the Deby's wind at the beach. But there are cheaper models out there.
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1360. Grothar
Quoting etxwx:

Is that the Nair Model?


LOL.
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1359. Grothar
We are getting a little outflow for the first time.

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1358. etxwx
Quoting Grothar:
This must have been a busy year.


Is that the Nair Model?
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Quoting Grothar:
I just found one of my first hurricane tracking maps. I thought you might be interested.



*Rolling on floor laughing* How the heck did you tracked hurricanes in the 1700s ;)
Member Since: August 1, 2011 Posts: 28 Comments: 7897
1354. LemieT
I've been reading the blog for a few days, and I can't help wondering why the ITCZ is such an issue for 99L, when Ivan and Emily were roughly just as south as this. How about Tomas in 2010? Some thought he would run aground in SA. As I see it, low level center, sustained, organized and heavy thunderstorm activity, north of 7.5degrees = possibility of development. IMO this should be at least given a 30% chance of development by now. But then again, percentages are moot.
Case in point, Tomas. On the day that it was named, I had already called it a TS the night before, and told my family (we're in Barbados) to prepare for a hurricane on Friday going into Saturday. Sometimes we get too caught up with the law of averages, and don't pay attention to what is actually happening.
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Quoting Grothar:
This must have been a busy year.



Geez what if one year would have that many storms.
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1352. Grothar
Quoting Astrometeor:
Hey everyone. I have now completely recovered from my wisdom teeth surgery last Wednesday. Like a lot of people on here, I am itching for a storm in the Atlantic. (stupid chiggers)

My birthday is coming up and I was thinking about asking my parents for a handheld anemometer. Does anyone have any suggestions on what to buy? Thanks in advance.


Anything but hard candy.
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1350. Grothar
I just found one of my first hurricane tracking maps. I thought you might be interested.

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Quoting Grothar:
This must have been a busy year.



2005?
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Hey everyone. I have now completely recovered from my wisdom teeth surgery last Wednesday. Like a lot of people on here, I am itching for a storm in the Atlantic. (stupid chiggers)

My birthday is coming up and I was thinking about asking my parents for a handheld anemometer. Does anyone have any suggestions on what to buy? Thanks in advance.
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1346. Grothar
This must have been a busy year.

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Well, never mind about post 1338, blob ain't got a chance. High shear, no convergence, no vorticity. Oh well, should have done some research before I asked.
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Wow the blog just died.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
The blog seems bored. I think they need to be reminded that there's an invest with a chance of development.
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1342. 7544
Quoting SFLWeatherman:
From me!!:)


good to see those maps adds excitment to the blog with 99l keep it up lets see whos gonna be right but ill go with this one better than polls lol
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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1024 PM AST MON JUL 30 2012

.UPDATE...SHOWERS AND THUNDERSTORMS SUBSIDED EARLY IN THE EVENING.
SATELLITE DERIVED BLENDED TPW IMAGERY AND 31/00Z SOUNDING INDICATES
THAT THERE IS AN AREA OF PRECIPITABLE WATER AROUND 2.4 INCHES OVER
THE ISLANDS. COMPUTER MODELS INDICATE THAT SHOWER AND
THUNDERSTORMS ACTIVITY IS STILL POSSIBLE LATE TONIGHT ACROSS THE
USVI AND EASTERN PUERTO RICO. THEREFORE...THE FLASH FLOOD WATCH
WAS ADJUSTED DUE TO TIMING...COVERING ONLY EASTERN PUERTO
RICO...VIEQUES...CULEBRA...AND THE USVI UNTIL 31/15Z AND THEN
COVERING ALL OF THE MUNICIPALITIES IN PUERTO RICO AS WELL AS THE
USVI UNTIL 31/20Z.

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It's probably been discussed, but I don't feel like going through 1000+ entry's so could you kind ladies and gentlemen tell me if there is anything to the blob near Puerto Rico? (Not the mid-Atlantic blob, that one is got real potential).
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Derived from (NHC) ATCF data for 99L for 31July12amGMT:

MinimumPressure had held at 1010millibars
MaximumSustainedWinds had held at 20knots(23mph)37km/h
Its vector had changed from West at 3.4mph(5.5km/h) to 284.4degreesWNWest at 9.4mph(15.2km/h)

For those who like to visually track 99L's path...
SLU is St.Lucia :: BGI is Barbados :: TAB is Tobaggo :: NTO is SantoAntao,CapeVerde

The Easternmost line-segment represents 99L's initial 30hours of travel.
The middle line-segment represents 99L's most recent 6hours of travel.

The longest line is a straightline projection through 99L's 2 most recent positions to a coastline.
On 31July12amGMT, 99L was headed toward passing over Dennery,St.Lucia in ~7days8hours from now

Copy&paste slu, tab, bgi, nto, 8.7n34.1w- 8.7n34.4w- 8.7n34.7w- 8.7n35.1w- 8.7n35.5w- 8.7n35.8w- 8.9n36.6w, 8.7n35.8w-13.91n60.889w into the GreatCircleMapper for more information
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The models are only good for about 72 hours!
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1334. Grothar
Quoting spathy:


Ok thats scary!
I was looking for a Carol B clip and could not find one.


Sick minds think alike.
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My Atlantic tracking map, Not an official NHC product
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting galvestonhurricane:


I think it will move more west or west northwest. If it does move more northwest, it will likely hit further south in SC or NC. Also, the reason why Irene wasn't stronger is because when storms get too far north the conditions quickly become less favorable for hurricanes.
That's true, but we still have had major hurricanes. A category four in 1821.
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I felt like making a map. :-)


Bigger Size
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Quoting galvestonhurricane:
I guess 99L could develop on Wednesday night. Speaking of Wednesday, I will be going to support my local Chick-Fil-A since Wednesday is Chick-Fil-A Appreciation Day.
chick fil hate?
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1327. Thrawst
Rained for the first time today in 6 days. It was really an anomalous sight. LOL

The SAL hung tough for those 6 days, I tell you. But the forecast is an increase in rain chances, which I REALLY REALLY like :) I can get some footage of lightning again :D
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Quoting mcluvincane:
Where's all the action tonight? Do i need to Q the GW peeps?


8.9 N, 36.6 W.
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Where's all the action tonight? Do i need to Q the GW peeps?
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Quoting Tropicsweatherpr:


At 00z.

AL, 99, 2012073100, , BEST, 0, 89N, 366W, 20, 1010, DB
Thanks!
Member Since: August 1, 2011 Posts: 28 Comments: 7897
1323. Thrawst
Quoting Tropicsweatherpr:


At 00z.

AL, 99, 2012073100, , BEST, 0, 89N, 366W, 20, 1010, DB


Just in case.. that's 8.9N and 36.6W

:o)
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1322. Thrawst
Quoting TropicalAnalystwx13:
Got my Graphical Tropical Weather Outlook out a little early tonight.

Please remember that these images are in no way associated with the National Oceanic and Atmospheric Administration or any other official government agency.



This looks REALLY good, but could you perhaps give a reasoning behind your prediction of 50% ? You want to make a point about a higher probability of tropical cyclone formation in the next 48 hours.

EDIT: If you had already, my bad. I just didn't see it. :P LOL
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Quoting Bluestorm5:
Btw, what's the current position for 99L. I want to make a quick graph.


At 00z.

AL, 99, 2012073100, , BEST, 0, 89N, 366W, 20, 1010, DB
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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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