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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I do think hurricane Irene was hyped a little.I mean c'mon "The east coast Katrina" is what some people called it.Let alone saying it would plow into NYC as a strong cat 2 to minimal cat 3.And plenty examples.

Glad she didn't turn out the way she was hyped on T.V our economy would be more in trouble than it is now.
Member Since: August 14, 2010 Posts: 10 Comments: 16406
Quoting DataNerd:





Here:Link


Consistently higher on the more northern track through the period, although some of that is due to the system's outflow itself.

Didnt show up... Took a look at other shear forecasts by the canadian, and others... It really appears, that shear isn't going to be a LARGE factor with this storm... as long as it stays out of caribbean.
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Quoting wxchaser97:


If that plays out...NO one will evacuate this time (if they even did for Irene)...that's what happens when things get *overhyped*

Remember Cantore standing on the Staton Island peer saying ..."in just a few hours..this all could be underwater..." lol!
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Quoting PensacolaDoug:





I doubt anyone here is "worrying". Speculating, discussing and perusing model outputs is what this site is about. That and agw.


Even I had to plus that one, Doug.
Member Since: July 17, 2009 Posts: 69 Comments: 25333

Quoting HurricaneDean07:
Its very possible we WILL be dealing with a Hurricane Ernesto, yes, probably weaker than Irene... but might take a go for Major Hurricane status. No telling yet.


If it goes north then yes it could with a US landfall but south is moderate TS and then death.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting HurricaneDean07:
Its very possible we WILL be dealing with a Hurricane Ernesto, yes, probably weaker than Irene... but might take a go for Major Hurricane status. No telling yet.




Meh. Maybe. I think until we have a td we can't reasonably talk intensity. Just too tricky without a closed low.


I'd say we are 36 hours away from TD if the current pattern holds, but if it starts to open up again or convection drops off that's out the window.
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Quoting DataNerd:





Here:Link


Consistently higher on the more northern track through the period, although some of that is due to the system's outflow itself.

If the storm took the northerly route, it would have an anticyclone to protect it, unlike in the Caribbean, where an anticyclone doesn't shield storms from strong trade winds.
Member Since: July 6, 2010 Posts: 113 Comments: 31438
Quoting HurricaneDean07:

Shear is forecasted to be better north of the caribbean, than it is IN the caribbean... Not sure what if youre talking about currently or not.





Here:Link


Consistently higher on the more northern track through the period, although some of that is due to the system's outflow itself.
Member Since: Posts: Comments:
Its very possible we WILL be dealing with a Hurricane Ernesto, yes, probably weaker than Irene... but might take a go for Major Hurricane status. No telling yet.
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Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting kwgirl:
You are correct TA. They have had quite a few good calls. But I think the way you defend them, you probably work for them. If you do, would you mind asking them to stop putting the very pregnant women on as "weather" girls. When they get that large, the navel protrudes and it starts to look like a pointer. If the women realized what they looked like, I bet they wouldn't do it.


NWS atlanta says they have gotten quite a few calls from people mistaking them with TWC telling them to get the pregnant women to move their belly because it is blocking the person's city....
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Quoting DataNerd:
Oh, and it would be traversing an area of much higher shear in that model as opposed to the carrib track so that would probably inhibit depth.



If it went that way you would be looking at, at most, a weaker cat 2 landfall.


trade winds in the caribbean will rip 99L apart

best chance for 99L to be a stronger storm is to go north of the islands, not go into the Caribbean
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Toward the end of the week, the ridge over the plains will retrograde westward and yet another weakness in the height field aloft develops over LA and E TX (so common this summer). Will need to bring rain chances back into the forecast starting Saturday. Sunday looks to possibly see some fairly decent coverage with deeper moisture advecting into the area and ridging backing to the west.

It should be noted that this pattern places the Gulf coast at the mercy of any possible tropical waves/systems in the Atlantic hurricane pipeline with little to no blocking ridging for protection.
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Quoting Grothar:


I don't know. I just liked the lines.



Should be around >180 hours or more. 120 hrs on current gfs run has it at the antilles no further.
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Quoting DataNerd:
Oh, and it would be traversing an area of much higher shear in that model as opposed to the carrib track so that would probably inhibit depth.



If it went that way you would be looking at, at most, a weaker cat 2 landfall.

Shear is forecasted to be better north of the caribbean, than it is IN the caribbean... Not sure what if youre talking about currently or not.
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Quoting HurricaneHunterJoe:
Got a ThunderBoomer here in San Diego County mountains,about 35-40 minutes and about 15-20 minutes very hard rain,a little thunder not much lightning. First rains since April. Most excellent!
..nevada and utah getting it as well, some flash flooding out there too
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Quoting Grothar:


I'm OK. I think it is fun that people will fight over anything! :)
Lol.I don't wanna get banned before the action heats up.Really keeping my eye on this one.Seems like another hard forecast track again.Lol.
Member Since: August 14, 2010 Posts: 10 Comments: 16406
Quoting trHUrrIXC5MMX:



VERY SCARY SCENARIO!


For The Bahamas, yes.
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Quoting RussianWinter:



I don't know. What's the timing for the end of the runs?


I don't know. I just liked the lines.
Member Since: July 17, 2009 Posts: 69 Comments: 25333
Quoting ilovehurricanes13:
what is going on at 10 north and 80 west!!


The Colombian low.
Member Since: April 29, 2009 Posts: 75 Comments: 14000
Got a ThunderBoomer here in San Diego County mountains,about 35-40 minutes and about 15-20 minutes very hard rain,a little thunder not much lightning. First rains since April. Most excellent!
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Well the flooding in florida has started..............................FLOOD ADVISORY
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
312 PM EDT MON JUL 30 2012

FLC017-302115-
/O.NEW.KTBW.FA.Y.0057.120730T1912Z-120730T2115Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
CITRUS FL-
312 PM EDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
WESTERN CITRUS COUNTY IN FLORIDA.
THIS INCLUDES THE CITIES OF...BEVERLY HILLS...CRYSTAL RIVER...
HOMOSASSA SPRINGS


* UNTIL 515 PM EDT

* AT 312 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
RAINFALL RATES OF TWO TO THREE INCHES PER HOUR ASSOCIATED WITH
THUNDERSTORMS OVER THE ADVISED AREA...LOCALIZED FLOODING IS
IMMINENT OR OCCURRING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

KEEP CHILDREN FROM BEING SWEPT AWAY IN FLOODED DITCHES AND DRAINS.
FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND MAY STALL YOUR
VEHICLE. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP
VEHICLES OFF THE ROAD. TURN AROUND...DONT DROWN.

&&

LAT...LON 2902 8246 2870 8242 2870 8273 2872 8273
2875 8270 2878 8272 2877 8274 2879 8276
2882 8274 2887 8274 2889 8270 2890 8270
2899 8276

$$
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Quoting kwgirl:
You are correct TA. They have had quite a few good calls. But I think the way you defend them, you probably work for them. If you do, would you mind asking them to stop putting the very pregnant women on as "weather" girls. When they get that large, the navel protrudes and it starts to look like a pointer. If the women realized what they looked like, I bet they wouldn't do it.

LOL. I'm 15, I don't have a job...much less at The Weather Channel. I just defend them because, ignoring all the unimportant series aired, they have good information. I mean the director of the NHC used to be their Hurricane specialist...
Member Since: July 6, 2010 Posts: 113 Comments: 31438
Oh, and it would be traversing an area of much higher shear in that model as opposed to the carrib track so that would probably inhibit depth.



If it went that way you would be looking at, at most, a weaker cat 2 landfall.
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Member Since: July 21, 2011 Posts: 83 Comments: 7167
Quoting Grothar:


Hey, TA What do you think of this ensemble??

It looks like a US landfall to me.
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30/1745 UTC 9.0N 37.1W TOO WEAK 99L -- Atlantic
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593. yoboi
Quoting RetainingH2O:
I believe 99L is heading for S.E. Texas. My son is getting married on August 11th... and so far everything else seems to be pre-disastered. In-laws already bickering, etc... normal stuff. We may as well have a hurricane too.

Hope I'm wrong, but based on the previous 2-weeks.... a hurricane would be reasonable.



look at the bright side it might make things more peaceful....
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Quoting TropicalAnalystwx13:






VERY SCARY SCENARIO!
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Quoting TropicalAnalystwx13:

Every bit of so called "hype" The Weather Channel produced during Irene was warranted. The storm caused nearly 20 billion dollars in damage.
You are correct TA. They have had quite a few good calls. But I think the way you defend them, you probably work for them. If you do, would you mind asking them to stop putting the very pregnant women on as "weather" girls. When they get that large, the navel protrudes and it starts to look like a pointer. If the women realized what they looked like, I bet they wouldn't do it.
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Quoting Grothar:


Hey, TA What do you think of this ensemble??



I think I'll have a go :D


All of them too far north. Ensemble appears to rely on developing the system no later than 57 hours out into a fairly deep ts or even a cat 1. Without that depth there is no way you can see that WNW component because current ridging in the Atlantic is too strong, and until around Tuesday of next week I wouldn't expect to see any changes to that pattern.

If the system did develop this quickly it would of course mean we would be looking at a more WNW track early ending with NW at the end of the period but I just don't see it organizing fast enough, nor the ridge dropping out that quickly, for that scenerio.


Again, airing with the GFS as it has done pretty well the last few years and it seems to have a very good handle on the ridging issue.

Edit: When I say GFS referring to the AP runs further south of the mean. If this is New GFS run then I will have to re-consider because I would still say that's too over confident on development.
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Quoting ncstorm:


Please dont let TWC see that..the way they hyped Irene last year they would have a field day with that run warning all Northerners to evacuate
Luckily it is just one member, now if every single member and model called for something similar then hype is needed.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
587. yoboi
Quoting Grothar:


I've always had a fondness for models.



right said fred???? i hope ya get the joke....
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I believe 99L is heading for S.E. Texas. My son is getting married on August 11th... and so far everything else seems to be pre-disastered. In-laws already bickering, etc... normal stuff. We may as well have a hurricane too.

Hope I'm wrong, but based on the previous 2-weeks.... a hurricane would be reasonable.
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Gee south Carolina is getting whacked big time today...................BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHARLESTON SC
427 PM EDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN CHARLESTON HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
CENTRAL EFFINGHAM COUNTY IN SOUTHEAST GEORGIA...
NORTHERN BEAUFORT COUNTY IN SOUTHEAST SOUTH CAROLINA...
SOUTH CENTRAL COLLETON COUNTY IN SOUTHEAST SOUTH CAROLINA...
EXTREME SOUTHEASTERN HAMPTON COUNTY IN SOUTHEAST SOUTH CAROLINA...
CENTRAL JASPER COUNTY IN SOUTHEAST SOUTH CAROLINA...

* UNTIL 515 PM EDT

* AT 428 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
SEVERE THUNDERSTORMS...ALONG A LINE EXTENDING FROM 11 MILES WEST OF
CLYO TO POCOTALIGO...MOVING SOUTH AT 30 MPH.

PREPARE NOW FOR THE FOLLOWING HAZARDS...
DAMAGING WINDS IN EXCESS OF 60 MPH...

* SOME LOCATIONS IN THE WARNING INCLUDE...
TARBORO...POCOTALIGO...SHELDON...GARDENS CORNER...TILLMAN...
RIDGELAND...SWITZERLAND...OLD HOUSE...LAUREL BAY...BEAUFORT MARINE
CORPS AIR STATION...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE SHELTER AS THUNDERSTORMS APPROACH.

REPORT HAIL...DOWNED TREES...LIMBS...AND POWER LINES DIRECTLY TO THE
CHARLESTON NATIONAL WEATHER SERVICE AT 1-888-383-2024...WHEN IT IS
SAFE TO DO SO.
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Quoting washingtonian115:
Yo Gro how are ya?.They may up the chances soon.


I'm OK. I think it is fun that people will fight over anything! :)
Member Since: July 17, 2009 Posts: 69 Comments: 25333
Quoting TropicalAnalystwx13:







can you plzs link that its hard too move srcll bar down
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Quoting 954FtLCane:


shhhhh....be quite. be vawy vawy quite. we're hunting for wabbits! (don't mention agw)

If you mention it..they will come!!.Lol.J/K.
Member Since: August 14, 2010 Posts: 10 Comments: 16406
Haven't looked at any models, any reports, anything. Just looking at upper air pattern and location and westward track....this thing is Yucatan bound.
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Quoting Grothar:


Hey, TA What do you think of this ensemble??



I don't know. What's the timing for the end of the runs?
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Quoting PensacolaDoug:





I doubt anyone here is "worrying". Speculating, discussing and perusing model outputs is what this site is about. That and agw.


shhhhh....be quite. be vawy vawy quite. we're hunting for wabbits! (don't mention agw)

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Quoting Grothar:


Hey, TA What do you think of this ensemble??

Irene and Floyd. Not in terms of intensity necessarily, but track.
Member Since: July 6, 2010 Posts: 113 Comments: 31438
Quoting Grothar:


Hey, TA What do you think of this ensemble??
...in that run,sure looks like a northward turn
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Quoting yoboi:


too early to say....

There is a reason why the GFS and EURO aren't too excited on 99L - so talking about the possible end scenarios at this point... dare I say it.., pointless BUT entertaining nonetheless! :)
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575. yoboi
Quoting MAweatherboy1:

This is looking more and more like an East coast storm.

The 12z GFS ensemble members seem to be taking it north despite the GFS itself taking it south:



too early to say....
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Quoting ncstorm:


Please dont let TWC see that..the way they hyped Irene last year they would have a field day with that run warning all Northerners to evacuate

Every bit of so called "hype" The Weather Channel produced during Irene was warranted. The storm caused nearly 20 billion dollars in damage.
Member Since: July 6, 2010 Posts: 113 Comments: 31438
Quoting TropicalAnalystwx13:
Here's how I would put it...

Stays in Caribbean (ECMWF/Operational GFS): 30%
Out to sea: 20%
Clips NE Caribbean and heads towards USA: 50%

Just educated guesses based on the pattern and latest model runs.


Hey, TA What do you think of this ensemble??
Member Since: July 17, 2009 Posts: 69 Comments: 25333
So what if we're talking about where the un-developed storm will go??.Why are you all offended?.That's the fun of weather.At least it's better than talking about politics.
Member Since: August 14, 2010 Posts: 10 Comments: 16406
Quoting galvestonhurricane:


We shouldn't worry about landfall locations until 99L actually develops. Good afternoon everyone!





I doubt anyone here is "worrying". Speculating, discussing and perusing model outputs is what this site is about. That and agw.
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Quoting wxchaser97:
This wouldn't be good.


Please dont let TWC see that..the way they hyped Irene last year they would have a field day with that run warning all Northerners to evacuate
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.

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