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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721. etxwx
Quoting LargoFl:
.......in his radio show..he said the power failure was because india stopped using COAL to generate electricity...i have NO idea what he is thinking because last i heard it was a monsoon that hit the power plants..again I..could be wrong also

BBC and NYT both report that about 200 coal miners were temporarily trapped underground when the power for the lifts failed, so I'd take Limbaugh's pontificating about coal with a grain of salt..it's about as helpful as coal in your Christmas stocking. ;-)

The NYT story also mentions this, for what it's worth:
But despite the scale of the power failure, many Indians responded with shrugs. In the first place, India’s grid is still being developed and does not reach into many homes. An estimated 300 million Indians have no routine access to electricity.

Second, localized failures are routine. Diners do not even pause in conversation when the lights blink out in a restaurant. At Delhi’s enormous Safdarjung Hospital, doctors continued to rush around as hundreds of patients lay in darkened hallways.

Third, so many businesses employ backup generators that, for many, life continued without much of a hiccup. Dr. Sachendra Raj, the manager of a private Lucknow hospital, rented two new generators two months ago, and they were keeping the hospital’s dialysis machines running and the wards air-conditioned. “It’s a very common problem,” Mr. Raj said. “It’s part and parcel of our daily life.”


The cause of the failure seems to be a number of factors. It sounds like folks there are pretty resourceful...but it's still, as the BBC says: A "Complete mess" .
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Quoting Chiggy:
Both 12Z runs of GFS and EURO are pretty close in terms of track and intensity (or lack of it..). When these two models agree this well then for the moment their prediction is a SAFE bet!


Yeah you are right, but the caribbean is a complex place. everything can happen.

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in 72 hrs twins



looks like pottery will get some gentle heavy tropical rains
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Its better here than outside dats fer sho'

Temperature
91.0 °F
Feels Like 105 °F
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18Z DYNAMIC MODELS


18Z STATISTICAL MODELS
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Member Since: March 16, 2012 Posts: 127 Comments: 7948
Quoting ncstorm:


they want the primetime ratings..
I know :\ Still sad it's about profit these days, but business is business... still doesn't mean I have to like the idea :(
Member Since: August 1, 2011 Posts: 28 Comments: 8030
The 12Z ECMWF loses 99L once again in the Caribbean graveyard. The GFS and ECMWF are not too excited with this system. Anytime you see this scenario with those front runner models...it's for a good reason.
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Quoting Patrap:
That TCFA has been coming for over 24 hours now, MARK.

: )
waitin on the navy soon after sunset maybe

No Active Atlantic Tropical Warnings
July-31-12, 2:30:01 PM | Maritime.CDO@navy.mil (FWC-N CDO)
As of Tue, 31 Jul 2012 18:30:01 GMT
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Quoting Patrap:


Thanks Pat!
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Quoting Stormchaser2007:
12z CMC
Nice view, a Georges track, albeit weaker.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
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AL992012 - INVEST

Storm Relative 1km Geostationary Visible Imagery

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Hey guys-if anyone wants to read my first post you can.
Feedback is welcome. Just a little snapshot of myself.
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Quoting Stormchaser2007:
12z CMC


Further south, tracks it over the islands so obviously weaker.
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Quoting Methurricanes:
NHC Why do you have to build me up just to let me down, and mess me around?


You sound like Rick Astley!
Member Since: July 17, 2009 Posts: 71 Comments: 26483
Quoting MississippiWx:


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.


Thanks for your positivity! Let's see what happens in a few days..
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Quoting ProgressivePulse:
Keep a wary eye on the 0%er. The area may try to pull a fast one in the Central Bahamas.


It's gonna be like this
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Quoting Bluestorm5:
I am going to kill NBC... not showing Phelps' races live? And the livestream isn't working at all.


If it helps, I think he was swimming.
Member Since: July 17, 2009 Posts: 71 Comments: 26483
12z CMC
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99L is starting to get that blossoming "look" and overall rotation but still below 10N.....Looking real good at the moment in a Tutt free environment until it gets to around 55W (see below). It's going to be a real interesting watch over the next 48 hours; "if" it is able a organize and break out from the ITCZ within the next 48, the models might shift to the North where the CMC has been for the past two days. Then we have to look at how sheer impacts the system.

Link
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Quoting ncstorm:
the Euro just killed 99L..



Not surprised. Didn't even initialize a low either.
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Quoting Bluestorm5:
None of them. Even Bravo as well.


they want the primetime ratings..
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That TCFA has been coming for over 24 hours now, MARK.

: )
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Arizona now joins the severe storm party today.....................
BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1138 AM MST TUE JUL 31 2012

THE NATIONAL WEATHER SERVICE IN FLAGSTAFF HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
SOUTH CENTRAL NAVAJO COUNTY IN NORTHEAST ARIZONA...

* UNTIL NOON MST

* AT 1134 AM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR
ARIPINE...OR 17 MILES EAST OF FOREST LAKES...AND MOVING NORTHWEST
AT 15 MPH. ANOTHER SEVERE THUNDERSTORM CAPABLE OF PRODUCING
QUARTER SIZE HAIL WAS LOCATED 1 MILE EAST OF
HEBER-OVERGAARD...ALSO MOVING NORTHWEST AT 15 MPH.

* THE SEVERE THUNDERSTORMS WILL BE NEAR...
HEBER-OVERGAARD CURRENTLY
RURAL SOUTHWESTERN NAVAJO COUNTY

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...FREQUENT CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY! LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS.
REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE
STRUCK BY LIGHTNING.



LAT...LON 3457 11075 3471 11047 3425 11030 3420 11043
TIME...MOT...LOC 1836Z 153DEG 14KT 3443 11053
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Quoting Bluestorm5:
I am going to kill NBC... not showing Phelps' races live? And the livestream isn't working at all.


No you're not. NBC is a large corporation that can do what they want.

None of us like it, but, we have to tough it out.
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Quoting TropicalAnalystwx13:
We're on track with the 2011 Atlantic hurricane season thus far. Tropical Storm Emily formed on August 1, and it appears that Tropical Depression Five will develop either tomorrow or August 2.
But its probable we will reach the F storm first than last year.
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Quoting Methurricanes:
Try, NBC Sports, CNBC or MSNBC on top of your local NBC stations.
None of them. Even Bravo as well.
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POSS T.C.F.A.
XX/INV/99L
MARK
9.75N/42.53W


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the Euro just killed 99L..

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Quoting Bluestorm5:
I am going to kill NBC... not showing Phelps' races live? And the livestream isn't working at all.
Try, NBC Sports, CNBC or MSNBC on top of your local NBC stations.
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Quoting LargoFl:
..GT we dont want this anywhere near florida huh..most area's are still waterlogged,even if it comes as a tropical storm
We already had our storm in Debby, so yes I agree, some areas are probably in surplus.
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Keep a wary eye on the 0%er. The area may try to pull a fast one in the Central Bahamas.
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Gain some latitude 9.6N at 18z Best track.
Member Since: April 29, 2009 Posts: 75 Comments: 14326
Quoting GTcooliebai:
My favorite model Experimental FIM in PWAT mode:



Nice GT. Thanks for sharing!
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I am going to kill NBC... not showing Phelps' races live? And the livestream isn't working at all.
Member Since: August 1, 2011 Posts: 28 Comments: 8030
Quoting Patrap:


..gee my local met was right yesterday..north florida..already water logged is going to get so much more today and the next few days he says..hopefully this will pick up some speed and get away from florida
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Finally picked up some wind (20 knots, now up to 25):

AL, 99, 2012073118, , BEST, 0, 96N, 413W, 25, 1010, DB, 34, NEQ, 0, 0, 0, 0, 1011, 150, 80, 0, 0, L, 0, , 0, 0, INVEST, S,
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My favorite model Experimental FIM in PWAT mode:

Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting Hurricane1956:
In my opinion the tropical wave by Espanola should be monitored,don't see a lot of shear,people are not paying attention to this feature,they are concentrated more on the other wave in the middle of the Atlantic and we have this one very close to home,I remember Andrew in 1992 was just a tropical wave a little bit East and North of this wave and become a monster,not trying to make any comparison but in my humble opinion this wave should be watch carefully,any thoughts about this??,thank you.

Its vorticity maximum remains well south of where the actual thunderstorm activity is thanks to unfavorable wind shear. While shear is lowering, it's probably too late. Land interaction will also be a huge factor.
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Quoting Grothar:
NHC Why do you have to build me up just to let me down, and mess me around?
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Quoting StormTracker2K:


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.


well the GFS was right, the high is past tahiti....
taking da plunge..
twas a big high too.
Thx to NOAA and TA13 for the SOI rise some more and then fall forecast
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Quoting GTcooliebai:
Invest 99L is looking better and better by the hour.
..GT we dont want this anywhere near florida huh..most area's are still waterlogged,even if it comes as a tropical storm
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Quoting Hurricane1956:
In my opinion the tropical wave by Espanola should be monitored,don't see a lot of shear,people are not paying attention to this feature,they are concentrated more on the other wave in the middle of the Atlantic and we have this one very close to home,I remember Andrew in 1992 was just a tropical wave a little bit East and North of this wave and become a monster,not trying to make any comparison but in my humble opinion this wave should be watch carefully,any thoughts about this??,thank you.


It's toast.
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Quoting Hurricane1956:
In my opinion the tropical wave by Espanola should be monitored,don't see a lot of shear,people are not paying attention to this feature,they are concentrated more on the other wave in the middle of the Atlantic and we have this one very close to home,I remember Andrew in 1992 was just a tropical wave a little bit East and North of this wave and become a monster,not trying to make any comparison but in my humble opinion this wave should be watch carefully,any thoughts about this??,thank you.
..yes i agree..anything that close should be watched
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for those posting Olympics results.. please understand that a great deal of people would like to watch tonight.. so quit posting the outcome.
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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.