Two African waves worth mentioning

By: Dr. Jeff Masters , 3:51 PM GMT on July 18, 2009

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There are two African tropical waves worth mentioning today, though neither looks particularly threatening. A tropical wave near 12N 45W, about 1200 miles east of the Lesser Antilles Islands (97 L), is moving west at 15 - 20 mph. This wave is now surrounded by an area of very dry air from the Sahara Desert. The dry air has disrupted most of the wave's heavy thunderstorm activity, and will continue to make it difficult for this system to develop over the next 2 - 3 days. Wind shear is a modest 10 knots over the disturbance, and should remain in the moderate 10 - 15 knot range over the next 2 - 3 days. Thereafter, shear is expected to rise to 20 - 30 knots. This morning's QuikSCAT pass showed no evidence of a surface circulation, and only a modest wind shift associated with 97L. The National Hurricane Center is giving this system a low (less than 30% chance) of developing into a tropical depression in the next 48 hours.

A second tropical wave now approaching the northern Lesser Antilles Islands is under 30 knots of wind shear, and has little prospect of development due to the high shear. However, the wave will bring heavy rain to the islands over the next two days.

None of the computer models are forecasting tropical storm development over the next seven days, and I don't expect either of the two African waves mentioned today to develop over at least the next three days.


Figure 1. Current satellite image of African wave 97L, 1200 miles east of the Lesser Antilles Islands.

I'll have an update Sunday afternoon.
Jeff Masters

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Disturbance at 101 hours on the GFS. Looks interesting.

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Quoting Patrap:
Im well aware what Im looking at 456,but you drop a Global Suite in here like ,..er..a Bomb,LOL

Thats kinda a water shed run Id say.
Lets see what the 00Z runs do.
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648. CUBWF
I think the new broad area of circulation is around 11n 63.5w
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Quoting Patrap:
Dont discount the GOM and the Front,..it has a potential for Genesis as much as anything in the Basin as well.





Especially in that water
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If the invest currently over the islands were to develop what kind of track can we expect ?
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456

What are your thoughts on Ex 97L as it enters the "sweet spot" near the Antilles?
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Dont discount the GOM and the Front,..it has a potential for Genesis as much as anything in the Basin as well.





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Quoting Patrap:
Im well aware what Im looking at 456,but you drop a Global Suite in here like ,..er..a Bomb,LOL

Thats kinda a water shed run Id say.


lol ok
Member Since: July 24, 2005 Posts: 407 Comments: 19076
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Im well aware what Im looking at 456,but you drop a Global Suite in here like ,..er..a Bomb,LOL

Thats kinda a water shed run Id say.
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12Z ECMWF

12Z GFS

12Z UKMET
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Patrap:
Well Im not seeing anything that would be in the Straits thru that time frame 456...

Only East coast Genesis comes out the GOM here.



Well what ur looking at is the 18Z run and only 1 model is out that fast, the NAM, which isn't popular when it comes to tropical cyclones. Also, the models were at the 12Z time frame.

here's the CMC for example.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Floater 1 - Visible Loop


The only Circulation seen in the Whole Basin is here,west of the Islands..moving W to WNW around 24mph
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637. afj3
Quoting stormwatcherCI:
Yes.

Thanks!
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Quoting afj3:
That thing off the Windward Islands looks impressive. Was it Faye last year that blew up in the Caribbean and looked threatening on radar but wasn't named because technically, it wasn't a tropical system yet?
Yes.
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Quoting K8eCane:


not sure what i think of all that Weather since i'm on southeast coast


All it means we should monitor that wave. That wave has had model support from day one (when it was near 40W around last Monday), but it was inconsistent at first, not the models seem to think it will develop.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
634. afj3
That thing off the Windward Islands looks impressive. Was it Faye last year that blew up in the Caribbean and looked threatening on radar but wasn't named because technically, it wasn't a tropical system yet?
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Notice the wave near the Islands was forecasted to be a Hurricane by the GFS around that area. It's interesting because now that it is forecast to develop in a few days by most of the global models, the GFS was the true model that picked it up first, even though the model dropped it, it's still there and back on the models. I guess if shear can clear out fast enough, this wave will most likely be 98L, the original wave that was forecasted to form in the first place. I'm still giving 97L a chance, but I cans see it getting absorbed into the wave near the Islands. Good to see you back Weather456 :)
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Well Im not seeing anything that would be in the Straits thru that time frame 456...

Only East coast Genesis comes out the GOM here.

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Floater - Water Vapor Loop
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Quoting GeoffreyWPB:
And what is the time frame for this 456? As Dr. Masters stated that the models showed no T.S. for the next seven days....and welcome back!


On the chart, the time frame is between 72 hrs and 1 week. I think Dr. Masters posted his update before the 12Z runs, but some models, like the CMC wa showing it since yesterday. I don't really understand what he meant.


And thanks everyone.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting K8eCane:


not sure what i think of all that Weather since i'm on southeast coast


Nothng to worry about now since there is nothing there. Just keep an eye out if anything develops.
Member Since: September 10, 2007 Posts: 0 Comments: 11430
A Big Welcome Back 456!
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Welcome back 456!
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WB... 456
Member Since: August 14, 2008 Posts: 4 Comments: 5030
And what is the time frame for this 456? As Dr. Masters stated that the models showed no T.S. for the next seven days....and welcome back!
Member Since: September 10, 2007 Posts: 0 Comments: 11430

Floater 1 - Visible Loop
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97l continies producing disorganized showers/some tstms.I give it a 60% chance once moving further wes tinto warm ocean/and more moisture condtions being given by the big convection area.
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Quoting Weather456:
Currently the Eastern CONUS is experiencing seasonable cool temperatures thanks in part to a trough dipping across the region. However, this trough will also be involved in initiating a tropical cyclone next week. A trough split situation is expected to coincide with the arrival of the wave as it enters the Western Atlantic. Most models are indicating that the trough will continue to dig south and amplify until a cut-off low forms over the GOM and heads SW. While this occurs, a ridge builds east of this trough split over the SW ATL while at the same the tropical wave will moving through the area. Most of the reliable global models indicate this will spark cyclogenesis and the slow will ride up the USA east of the aforementioned upper trough. During this time, shear is expected to be around 5-15 knots and SSTs are already well above 26C. It seems the next invest will likely be the tropical wave near the islands.



Welcome back. Missed you last night with your words of wisdom. Behave yourself now so it doesn't happen again please !
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Quoting Weather456:
Currently the Eastern CONUS is experiencing seasonable cool temperatures thanks in part to a trough dipping across the region. However, this trough will also be involved in initiating a tropical cyclone next week. A trough split situation is expected to coincide with the arrival of the wave as it enters the Western Atlantic. Most models are indicating that the trough will continue to dig south and amplify until a cut-off low forms over the GOM and heads SW. While this occurs, a ridge builds east of this trough split over the SW ATL while at the same the tropical wave will moving through the area. Most of the reliable global models indicate this will spark cyclogenesis and the slow will ride up the USA east of the aforementioned upper trough. During this time, shear is expected to be around 5-15 knots and SSTs are already well above 26C. It seems the next invest will likely be the tropical wave near the islands.





not sure what i think of all that Weather since i'm on southeast coast
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Quoting Weather456:
Currently the Eastern CONUS is experiencing seasonable cool temperatures thanks in part to a trough dipping across the region. However, this trough will also be involved in initiating a tropical cyclone next week. A trough split situation is expected to coincide with the arrival of the wave as it enters the Western Atlantic. Most models are indicating that the trough will continue to dig south and amplify until a cut-off low forms over the GOM and heads SW. While this occurs, a ridge builds east of this trough split over the SW ATL while at the same the tropical wave will moving through the area. Most of the reliable global models indicate this will spark cyclogenesis and the slow will ride up the USA east of the aforementioned upper trough. During this time, shear is expected to be around 5-15 knots and SSTs are already well above 26C. It seems the next invest will likely be the tropical wave near the islands.





welcome back 456
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WB from the netherworld 456
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Quoting Weather456:
Currently the Eastern CONUS is experiencing seasonable cool temperatures thanks in part to a trough dipping across the region. However, this trough will also be involved in initiating a tropical cyclone next week. A trough split situation is expected to coincide with the arrival of the wave as it enters the Western Atlantic. Most models are indicating that the trough will continue to dig south and amplify until a cut-off low forms over the GOM and heads SW. While this occurs, a ridge builds east of this trough split over the SW ATL while at the same the tropical wave will moving through the area. Most of the reliable global models indicate this will spark cyclogenesis and the slow will ride up the USA east of the aforementioned upper trough. During this time, shear is expected to be around 5-15 knots and SSTs are already well above 26C. It seems the next invest will likely be the tropical wave near the islands.




Hi Weather456 welcome back
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97 has been removed from the NOAA Page as well.


Atlantic and Caribbean Tropical Satellite Imagery

Das Kaput.

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Currently the Eastern CONUS is experiencing seasonable cool temperatures thanks in part to a trough dipping across the region. However, this trough will also be involved in initiating a tropical cyclone next week. A trough split situation is expected to coincide with the arrival of the wave as it enters the Western Atlantic. Most models are indicating that the trough will continue to dig south and amplify until a cut-off low forms over the GOM and heads SW. While this occurs, a ridge builds east of this trough split over the SW ATL while at the same the tropical wave will moving through the area. Most of the reliable global models indicate this will spark cyclogenesis and the slow will ride up the USA east of the aforementioned upper trough. During this time, shear is expected to be around 5-15 knots and SSTs are already well above 26C. It seems the next invest will likely be the tropical wave near the islands.



Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting IpswichWeatherCenter:


97L is still an invest, somehow.
dropped
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Quoting AllStar17:


And I suspect it will never be one. Everytime there is a big blow up of convection, everyone jumps on it, but the entity really to watch is Ex 97L IMO.


97L is still an invest, somehow.
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610. HadesGodWyvern (Mod)
Japan Meteorological Agency

Tropical Disturbance Summary (1800z 18JUL)
=========================================
At 3:00 AM JST, Low Pressure Area (1008 hPa) located at 10.0N 135.0E has 10 minute sustained winds of 15-20 knots and is reported as almost stationary
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Looking closely on the Viz,FLoater 1..a Circulation is noted west of the Leewards, ahead of the Convective Burst over the Islands,

Floater 1 - Visible Loop
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I think ex invest 97 L will be sucked up into the big blob of convection.
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Now that we have a lull between invests, it is a good time for everybody to put in how we like our crow cooked. This includes the NHC also

i like mine browned
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Quoting Patrap:
97 is das kaput.

Its behind enough Dry air to make a New Sahara.
lmao!
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Thanks Adrian.
Member Since: September 10, 2007 Posts: 0 Comments: 11430
The Invest due,will be the one here...on Floater 1




But not until the NAVY or NHC calls it.
A floater is always on the Fray early.
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Quoting Patrap:
97 is das kaput.

Its behind enough Dry air to make a New Sahara.

It needs to back up into that moisture field.
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Just looking at the caribbean right now is a classic sign of a maturing nino with this upper trof in place.As of now i dont expect development with wave approaching the northern islands as conditions again are rather hostile.Models try to relax those westerlies in a few days but we'll see.GFS brings the disorganized wave into southern florida mid-week.
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Quoting weatherwatcher12:

So the circulation has made its way into the Caribbean?


It is possible... the next few Sat images we get will let us know if that's the case. It is possible (obviously due to shear) that a weak developing low could have tried to have gotten organized but it detached itself from the main convection and if that's the case then it should die out soon.
Member Since: August 14, 2008 Posts: 4 Comments: 5030

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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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