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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2221. LargoFl
Quoting gulfbreeze:
We are watching!
..yes we are watching this closely huh..water temps in the gulf..high 80's..around texas its 90 whew
Member Since: August 6, 2011 Posts: 4 Comments: 36847
I agree with those on a more southerly track...it's taking it's time to develop. The longer it does that...the more southern it will be. My opinion at this time is Caribbean into the "Hot Tub"...Hope I'm wrong....
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06z GFS showed 99L slowly developing until reaching the Western Caribbean where real intensification begins.
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Quoting Neapolitan:
Okay, now they've bumped the winds up 5 knots:

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, M,


And more north in latitude than the 10.2N.
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Quoting Neapolitan:
Okay, now they've bumped the winds up 5 knots:

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, M,


One more 5 knots bump, and it's a tropical storm winds. Is 99L a close circulation right now?
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Quoting ncstorm:


the CMC faltered a little yesterday and went south..I guess peer pressure got the better of it..LOL..but I dont see this tracking south in the Caribbean..It will be either tracking over the islands or just north of the islands..bahamas and SE USA afterwards..

when the GFS ran this storm as a hurricane for the first time at that 00z run..where did it take it into? It was North of the islands and SE Florida..always go back to the first run especially with the GFS because it usually always come back to it..


Ive seen that happen time and time and time again!
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2215. GetReal



99L appears to be close to becoming a TD or TS Ernesto later today. I see there is plenty of speculation as to where this system is going.

The previous runs of the M.O.D. (model of doom) had been pretty consistant on bringing an Ivan type tracking system across the southern Caribbean, before it turned WNW towards the NW Caribbean.

The latest 1300 run of the MOD has shifted slightly northward, and Ernesto tracking west to WNW as a strong Cat 1 hurricane through the central Lesser Antilles. MOD brings Erneato towards, and possibly over Jamaica as a strong Cat 2 as it tracks WNW torwards the Caymans. Ernsto bombs as a Cat 4 in NW Caribbean.

MOD turns Ernesto NW towards the Yucatan Channel, and at the end of the run has a 920 mb hurricane sitting in the central GOM.

MOD is nearly always correct.
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2214. ncstorm
here is the 00z CMC with visualizing colors dooming Florida





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Notice how over the last 24hrs how 99L has moved WNW out of the ITCZ.

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2212. LargoFl
...rainfall totals for july
Member Since: August 6, 2011 Posts: 4 Comments: 36847
Okay, now they've bumped the winds up 5 knots:

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, M,

TD status imminent...
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Quoting washingtonian115:
Oh well that's just great....Well eh you Gulf coast residents watching this to?.
We are watching!
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Quoting yankeeslover:
i fly from upstate ny to orlando next friday 8/10.. should i start to worry alittle bit about this ruining my flight plans? i take vacation every 10 years..worried now
Nah, there's no concern about this hitting Florida on 8/10, although keeping the eye on it will be a good idea. Things changes fast.
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Quoting StormTracker2K:
I think we will have a TD at 5pm today. 99L is really looking good right now.



I think the NHC is just waiting for this current blow up to persist through a little longer. It was starting to develop an anti-cyclone yesterday and judging by satellite representation it looks as if it is ventilating very well in 3 of its 4 quadrants. 99L has been steadily organizing the last 48 hours. So, at the least I'd say we will see the percentages go up by tonight, if not by tonight, then by tomorrow morning we should be looking at a Tropical Depression.

Being at 10N leaves it a place to where it is very difficult to develop westerly winds. It needs to gain a bit more in latitude, but it should do that in time. Being at 10N does make this system very difficult to turn out to sea. I wonder what the percentages of storms that form in the area of 99L are at making landfall. I bet it is high, not just for the islands, but all those beyond as well.

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Quoting yankeeslover:
i fly from upstate ny to orlando next friday 8/10.. should i start to worry alittle bit about this ruining my flight plans? i take vacation every 10 years..worried now

It's likely there will be a strengthening tropical cyclone in the western Caribbean at that time. Pay close attention to The National Hurricane Center when they start advisories on this system.
Member Since: July 6, 2010 Posts: 113 Comments: 31428
2206. ncstorm
Quoting washingtonian115:
@ncstorms No we won't!.NOGAPS is a crappy model!.


LOL..now Wash, you know better..
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Good morning all

99L is still in its formative stages and should have no difficulty clearing the SA coast. Entry into the Caribbean near 12 still looks like a reasonable scenario to me. Classification as a TD could come later today if the overall organization and convection does not wane during the heat of the day. The NHC will want to see some consistency in this regard I would think.

Upper level conditions near the system are not ideal with shear values of 20 to 30 knots immediately to its North which may slow the organization process some during the day. All in all though we will likely see this continue to get its act together.
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2204. LargoFl
Just what we need here especially north florida...more rain, we will be turning back into swamp land shortly gee...............THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST CENTRAL AND SOUTHWEST
FLORIDA.

.DAY ONE...TODAY AND TONIGHT.

...THUNDERSTORM IMPACT...
ISOLATED THUNDERSTORMS AND SCATTERED SHOWERS ARE EXPECTED TO FORM
THIS MORNING. THESE STORMS WILL CONTINUE INTO THE AFTERNOON AND
BECOME LIKELY IN THE FAR NORTH...SCATTERED FOR CENTRAL LOCATIONS...
BUT REMAIN ISOLATED IN THE FAR SOUTH. GUSTY WINDS...LOCALLY HEAVY
RAINFALL...AND DEADLY CLOUD TO GROUND LIGHTNING WILL BE THE MAIN
HAZARDS WITH THE STORMS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

...THUNDERSTORM IMPACT...
SCATTERED THUNDERSTORMS ARE EXPECTED EACH DAY...SCATTERED DURING
THE DAYTIME AND ISOLATED OVERNIGHT. THESE STORMS MAY PRODUCE
GUSTY WINDS...LOCALLY HEAVY RAINFALL...AND DEADLY CLOUD TO GROUND
LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.

$$
Member Since: August 6, 2011 Posts: 4 Comments: 36847
Eight die in Indonesia landslides

LANDSLIDES triggered by heavy rains have killed eight people in Indonesia's eastern Maluku province, a local official says.

"Eight people were killed in three different locations in Ambon city," said Brory Tjokro, the city's search and rescue chief, adding that a further two people were missing.

"Heavy rains that poured all night caused landslides in the locations. Ambon city was also flooded," he said.

In June, three people were killed in the town when they were buried in a landslide caused by heavy rains.

Floods and landslides are common in Indonesia, which is prone to frequent bursts of heavy rain.
Member Since: September 30, 2007 Posts: 9 Comments: 15932
i fly from upstate ny to orlando next friday 8/10.. should i start to worry alittle bit about this ruining my flight plans? i take vacation every 10 years..worried now
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@ncstorms No we won't!.NOGAPS is a crappy model!.
Member Since: August 14, 2010 Posts: 10 Comments: 16383
2200. LargoFl
Quoting floridaboy14:
well i think it wont weaken in the eastern carribean. i just think it wont stregnthen. big difference. i am siding with TA13 on a track south of jamaica wnw towards the yucatan channel
....im with you on the southern track as well
Member Since: August 6, 2011 Posts: 4 Comments: 36847
2199. Grothar
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Loooooking Goood Lucy
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A track just North of PR would be bad for Florida; it would take it through the Hebert Box and most of us here know what that means............... :)
Member Since: August 8, 2006 Posts: 0 Comments: 8770
I certainly dont wish a storm over hispanola. But those mountains can really disrupt a storm.
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Quoting wunderkidcayman:
I say 99L LLCOC is now located at 10.3N 46.5W

yay I was almost on target

102N, 470W
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well i think it wont weaken in the eastern carribean. i just think it wont stregnthen. big difference. i am siding with TA13 on a track south of jamaica wnw towards the yucatan channel
Member Since: July 25, 2011 Posts: 0 Comments: 1102
2193. SLU
AL, 99, 2012080112, , BEST, 0, 102N, 470W, 25, 1009, LO, 0, , 0, 0, 0, 0,
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2192. ncstorm
Quoting StormTracker2K:


Wasn't the Nogaps one of 3 models who showed a FL landfall with Debby? Just saying.


they wont admit it when it comes to the NOGAPs..just let it be..
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If 99L makes it into the caribbean and continues on a WNW path the U.S Gulf coast will have to keep a watchful eye on it.I'm not going to predict strength as that is a whole week from now.
Member Since: August 14, 2010 Posts: 10 Comments: 16383
Looks further north on satellite??
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Quoting TropicalAnalystwx13:
I doubt 99L strengthens enough to come out of the Caribbean. It should pass through the Windward Islands around 14N and move west-northwest and be located just south of Jamaica in 5-6 days.


Actually a WNW path from there will take it over Hispaniola and Cuba.
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2188. ncstorm
Quoting StormTracker2K:


Nogaps and CMC have stuck to their guns and the now the Euro has followed suite.


the CMC faltered a little yesterday and went south..I guess peer pressure got the better of it..LOL..but I dont see this tracking south in the Caribbean..It will be either tracking over the islands or just north of the islands..bahamas and SE USA afterwards..

when the GFS ran this storm as a hurricane for the first time at that 00z run..where did it take it into? It was North of the islands and SE Florida..always go back to the first run especially with the GFS because it usually always come back to it..
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Quoting TropicalAnalystwx13:

A broken clock is right twice a day..


Wasn't the Nogaps one of 3 models who showed a FL landfall with Debby? Just saying.
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it looks to me like a stronger storm will head further north. The Bamms models suggest it as does the CMC. The shallow Bam take it further west and the Mid and Deeper take it further north. Hence my thinking. Earlier developments further north. Looks like the models that take it further west are all keeping the storm rather weak. JMHO.
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Still no change in strength according to ATCF; only the location is different:

AL, 99, 2012080112, , BEST, 0, 102N, 470W, 25, 1009, LO, 0, , 0, 0, 0, 0,


See #2211
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2184. Chiggy
Quoting Chiggy:

Though it doesn't make sense, EURO weakens it but moves it more northerly - ought to take a more southern part instead like GFS.
I find the 06Z run much more plausible.


06Z GFS run I mean...
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Quoting ncstorm:
Well the crappy Nogaps is still insisting on a NW path..oh well


LOL!
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Quoting Bluestorm5:
99L is very impressive. Can understand why NHC set it at 60%. It's almost a tropical storm right now.


I know its should be at 70% or 80%

Quoting StormTracker2K:
I think we will have a TD at 5pm today. 99L is really looking good right now.


nah I think maybe at 11am or 2pm
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2181. Grothar
Quoting mcluvincane:


Very nice looking, its been a while


Gee, thanks, But I don't remember posting a picture of myself lately :)
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Quoting ncstorm:
Well the crappy Nogaps is still insisting on a NW path..oh well

A broken clock is right twice a day..
Member Since: July 6, 2010 Posts: 113 Comments: 31428
2179. Chiggy
Quoting StormTracker2K:


Looking at a more northerly route. The Euro shifted north and now brings 99L to PR and then into the Bahamas.

Though it doesn't make sense, EURO weakens it but moves it more northerly - ought to take a more southern part instead like GFS.
I find the 06Z run much more plausible.
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Quoting weaverwxman:
I love the fact that we may have a storm to track. What I hate is we might have a storm to track through the Islands. What I really hate is the possibility of a storm at my front door next weekend. Heres to hoping for a civil blog the next few days. Hoping for a harmless fish storm....



The AB High won't allow a fish storm.
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2177. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 36847
Quoting hurricaneeye:


Hurricane Cesar track, July 24th--29th 1996



Please, do not take this track, dear Ernesto
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Quoting ncstorm:
Well the crappy Nogaps is still insisting on a NW path..oh well


Nogaps and CMC have stuck to their guns and the now the Euro has followed suite.
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I doubt 99L strengthens enough to come out of the Caribbean. It should pass through the Windward Islands around 14N and move west-northwest and be located just south of Jamaica in 5-6 days...probably as an intensifying hurricane.
Member Since: July 6, 2010 Posts: 113 Comments: 31428
2173. Grothar
Quoting TropicalAnalystwx13:

You say it all the time, that's nothing new. ;)


TA, don't you think it would be a good idea to explain the "John Hope Rule" to the blog. This way it could avoid confusion about the dead zone.
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A few points to note from the CIMMS charts:

It has almost lost that western "dog leg" on the 850 vort chart. It is fully separating from the ITCZ.

Link

The Tutt cells have moved out of the way between it and the Caribbean/Greater Antilles on the 200mb chart:

Link

The system (they have a mind of their own) has taken the path of least resistence, sheer wise, below the daunting sheer to it's North and headed towards very favorable low sheer conditions over the next 48 hours at just the right speed:

Link

Translation? No significant impediments to attaining hurricane status over the next 72 hours that I can see at the moment.
Member Since: August 8, 2006 Posts: 0 Comments: 8770


Hurricane Cesar track, July 24th--29th 1996
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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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