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 wunderkidcayman:
for 99L and the TWO and formation I think
8pm 50% red
2am 70% red
5am formation of TD 4 or TS Ernesto

for 99L's track I say steady W-WNW track untill it reaches 75-85W where it will then turn NW-NNW

for 99L strength after formation
before landfall of E Caribbean Islands 70-75mph
when it reaches 73W 85-90mph
when it reaches 75W 100mph (ok this part I am being a little nice about- when it reaches 78-80W goes to 114mph as it hits the very very very high tropical cyclone heat potentials in the W caribbean)
when it reaches 85W and entering the GOM 120mph
and I will stop there

NOTE: BEFORE YOU START BICKERING TO ME THIS IS JUST MY THOUGHS ON THIS POSSIBLE OUTCOME...
May not be to out of the realm of possible outcomes.All depends if shear is favorable in the caribbean or not.
Member Since: August 14, 2010 Posts: 10 Comments: 17073
1070. LargoFl
..oh boy right on the howard franklin bridge at rush hour
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Quoting Pocamocca:
Why do you keep quoting the trolls MississippiWx? Hint: If you don't quote them or give them any attention, they will go away and find another blog/forum to disrupt.

Please.


If any of you didn't know already, this is JFV as well. Fairly obvious through the emails I've gotten from this person today.
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Does anyone wish to discuss the timing of the storm on tropics chat?
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Quoting Pocamocca:
Why do you keep quoting the trolls MississippiWx? Hint: If you don't quote them or give them any attention, they will go away and find another blog/forum to disrupt.

Please.


Lol, if only. These trolls have been here for several years.
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1065. LargoFl
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Nevermind, found this.

Member Since: July 6, 2010 Posts: 113 Comments: 32255
1063. KEEPEROFTHEGATE (Mod)
Quoting CorfidiFan:
I this wanted too say i am not a troll so pls lets stop that and talk about weather olny
you are trying to hard
Member Since: July 15, 2006 Posts: 173 Comments: 54283
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for 99L and the TWO and formation I think
8pm 50% red
2am 70% red
5am formation of TD 4 or TS Ernesto

for 99L's track I say steady W-WNW track untill it reaches 75-85W where it will then turn NW-NNW

for 99L strength after formation
before landfall of E Caribbean Islands 70-75mph
when it reaches 73W 85-90mph
when it reaches 75W 100mph (ok this part I am being a little nice about- when it reaches 78-80W goes to 114mph as it hits the very very very high tropical cyclone heat potentials in the W caribbean)
when it reaches 85W and entering the GOM 120mph
and I will stop there

NOTE: BEFORE YOU START BICKERING TO ME THIS IS JUST MY THOUGHS ON THIS POSSIBLE OUTCOME...
Member Since: June 13, 2009 Posts: 2 Comments: 12140
1059. JLPR2
Quoting TropicalAnalystwx13:
The Lesser Antilles/Leeward Islands (what's the difference?) need to prepare for a strong tropical storm for the weekend.


Leeward islands are the one I believe north of Guadeloupe.
Windward islands are the one to the south.
Member Since: September 4, 2007 Posts: 7 Comments: 8732
1058. LargoFl
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Quoting kmanislander:
Keeping both eyes on 99l LOL



That's what the graphic is showing 2 blue eyes....
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back later
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Quoting StormTracker2K:


looks very impressive. These 2 models did this back in 04 as well. No question we have a problem down the road as 99L will likey hit the US and I think this could be a big storm as well.
I'm not discounting anything out yet ST2K.Both solutions are possible that 99L once it get's ion the caribbean could be rip apart or intensify.

TWXA13 has posted various maps and charts stating how the caribbean isn't that bad actually for shear.Not sure who it'll play out over the next few days.Also to not a TUTT is suppose top setting up over the Bahama's causing unfavorable conditions if 99L goes north of the islands.
Member Since: August 14, 2010 Posts: 10 Comments: 17073
Good afternoon everyone! I still think 99L will move more WNW and split the two model camps...

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Quoting kmanislander:
Keeping both eyes on 99l LOL

lol
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Not too bad in OH:
Member Since: February 11, 2012 Posts: 0 Comments: 9731
1048. Patrap
Also, Low Latitude Runners like this tend to be problematic downstream if Conditions allow.


And remember, the X factor is in play, as this years Atmo, is not last years atmo, nor 2002's.

There is more WV, and more Latent Heat available..as we continue to terra form our Home Planets Life sustaining Biosphere.
Member Since: July 3, 2005 Posts: 426 Comments: 128630


A few model runs are hinting on a possible Hurricane David type path, I'm not saying that this system will ever reach that intensity, but if it does develop into a tropical cyclone, the way the steering currents are laid out, it could take a similar path.
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The Lesser Antilles/Leeward Islands (what's the difference?) need to prepare for a strong tropical storm for the weekend.
Member Since: July 6, 2010 Posts: 113 Comments: 32255
Keeping both eyes on 99l LOL

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1044. nigel20
99L

BBL
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The westside of FL is in for some very nasty weather over the next several days. Expect some areas to get several inches of rain causing serious flooding of low lying areas so remember "Turn around don't drown".


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1042. LargoFl
Quoting Patrap:


It has a good surface circ forming, Low Shear ahead, supportive SST's and well, Im with Masters on this so far, and the NHC.

It's a good time for all to review their Home/evac Hurricane Game Plan. Its just going to get busier as we go thru Aug-Sept or the Peak Months..
..ok ty, ive been watching this all day long and it keeps looking better and better in the gulf
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WOW!!!:) TD by 5AM!!!
Quoting MississippiWx:
TPW loops would make one think that the center is slightly north of 10N. Also, it's fairly obvious that the ITCZ separation is underway.

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Damrey (55kts)



Saola (75kts)



Saola is forecast to be a Cat 3 coming into China.
Member Since: February 11, 2012 Posts: 83 Comments: 7833
1039. Grothar
Now, what is going to happen next is small bands of moisture will try and start feeding in from the SW. So you will see small flare-ups of convection in the SW quadrant in a little while. Believe it or not, this sometimes gives a little "lift" to a system.
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1036. Patrap
Quoting LargoFl:
............pat do you think this might develop?


It has a good surface circ forming, Low Shear ahead, supportive SST's and well, Im with Masters on this so far, and the NHC.

It's a good time for all to review their Home/evac Hurricane Game Plan. Its just going to get busier as we go thru Aug-Sept or the Peak Months..
Member Since: July 3, 2005 Posts: 426 Comments: 128630
1035. LargoFl
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The NHC loops just updated again. Nice convective burst closer to 10N after some waning the past 6 hours. The persistence is there for sure at this point.
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Quoting MississippiWx:
TPW loops would make one think that the center is slightly north of 10N. Also, it's fairly obvious that the ITCZ separation is underway.

I agree. We'll have to see how the system reacts convectively after separating from the ITCZ.
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Quoting SFLWeatherman:
Q. ok so what wiil 99L be at 8PM
A. 30%
B. 40%
C. 50%
D. 60%
E. 70%
F. 80%
Q. what time will 99L be a TD or TS
A. 11PM
B. 5AM
C. 11AM
D. 5PM


50% TD 5AM TS 11AM

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Quoting ilovehurricanes13:
very bad!!


I just hope this storm can delay a land fall by just one day. C'mon, only 1 day.
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Quoting MAweatherboy1:
It's always hard to tell what the NHC will do, a lot depends on the forecaster, but I think they'll give it 40% at 8PM... Personally I think closer to 60%.
It depends on who is working at the desk and typing the TWO. It could be anywhere from 30% to near 100% for all we know.
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Quoting SFLWeatherman:
Q. ok so what wiil 99L be at 8PM
A. 30%
B. 40%
C. 50%
D. 60%
E. 70%
F. 80%
Q. what time will 99L be a TD or TS
A. 11PM
B. 5AM
C. 11AM
D. 5PM

50% and tomorrow at 5pm
Member Since: February 13, 2012 Posts: 11 Comments: 3768
Quoting MiamiHurricanes09:
I'd give 99L a 60% chance of developing into a tropical cyclone over the next 48 hours. The only thing I find interesting is the two best global models' (GFS and ECMWF) resilience to develop 99L into anything more than an open wave.


looks very impressive. These 2 models did this back in 04 as well. No question we have a problem down the road as 99L will likey hit the US and I think this could be a big storm as well.
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1027. LargoFl
meanwhile back at the real weather.............................BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
438 PM EDT TUE JUL 31 2012

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
EASTERN MONTGOMERY COUNTY IN CENTRAL MARYLAND...
NORTHERN PRINCE GEORGES COUNTY IN CENTRAL MARYLAND...
HOWARD COUNTY IN CENTRAL MARYLAND...

* UNTIL 530 PM EDT

* AT 436 PM EDT...A SEVERE THUNDERSTORM WAS DETECTED NEAR OLNEY...AND
WAS MOVING NORTHEAST AT 15 MPH. THIS STORM IS CAPABLE OF PRODUCING
DAMAGING WINDS IN EXCESS OF 60 MPH.

* LOCATIONS IMPACTED INCLUDE...
COLUMBIA...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...MOVE INDOORS TO A
STURDY BUILDING AND STAY AWAY FROM WINDOWS. WHEN IT IS SAFE TO DO
SO...REPORT SEVERE WEATHER TO LOCAL LAW ENFORCEMENT OR TO THE
NATIONAL WEATHER SERVICE.

LAT...LON 3933 7705 3923 7676 3903 7696 3912 7716
TIME...MOT...LOC 2038Z 207DEG 14KT 3916 7701



HTS
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1026. Patrap
Storm Relative 1km Geostationary Visible Imagery

Member Since: July 3, 2005 Posts: 426 Comments: 128630
1025. pcola57
Quoting SFLWeatherman:
Q. ok so what wiil 99L be at 8PM
A. 30%
B. 40%
C. 50%
D. 60%
E. 70%
F. 80%
Q. what time will 99L be a TD or TS
A. 11PM
B. 5AM
C. 11AM
D. 5PM


Q#1. B

Q#2. Tomorrow
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1024. JLPR2
Quoting washingtonian115:
T.D by tomorrow morning in my opinion.All though the NHC may go the conservative route and issue T.D status tomorrow night.


I'll go with 5pm tomorrow.
Member Since: September 4, 2007 Posts: 7 Comments: 8732
It's always hard to tell what the NHC will do, a lot depends on the forecaster, but I think they'll give it 40% at 8PM... Personally I think closer to 60%, and TD late tomorrow or Thursday morning.
Member Since: February 11, 2012 Posts: 83 Comments: 7833
1022. KEEPEROFTHEGATE (Mod)
Quoting MississippiWx:


And you are a troll. You were just poofed.
its not a troll its shower curtain boy and jason is really he's friend

great way to fool some but not all
Member Since: July 15, 2006 Posts: 173 Comments: 54283
Quoting SFLWeatherman:
Q. ok so what wiil 99L be at 8PM
A. 30%
B. 40%
C. 50%
D. 60%
E. 70%
F. 80%
Q. what time will 99L be a TD or TS
A. 11PM
B. 5AM
C. 11AM
D. 5PM

D. and 5Pm. Tomorrow.
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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.