Dr. Jeff Masters' WunderBlog

Two African waves worth mentioning
Posted by: Dr. Jeff Masters, 15:51 GMT le 18 juillet 2009 +2
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
Categories: Hurricane
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601. Patrap 20:50 GMT le 18 juillet 2009    
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Member Since: 3 juillet 2005 Posts: 377 Comments: 113004
602. hurricane23 20:50 GMT le 18 juillet 2009    
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.
Member Since: 14 mai 2006 Posts: 8 Comments: 13331
603. hunkerdown 20:52 GMT le 18 juillet 2009    
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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604. Patrap 20:53 GMT le 18 juillet 2009    
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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605. GeoffreyWPB 20:53 GMT le 18 juillet 2009    
Thanks Adrian.
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606. stormpetrol 20:53 GMT le 18 juillet 2009    
Quoting Patrap:
97 is das kaput.

Its behind enough Dry air to make a New Sahara.
lmao!
Member Since: 29 avril 2007 Posts: 0 Comments: 6497
607. K8eCane 20:54 GMT le 18 juillet 2009    
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
Member Since: 26 avril 2006 Posts: 5 Comments: 2496
608. StormFreakyisher 20:54 GMT le 18 juillet 2009    
I think ex invest 97 L will be sucked up into the big blob of convection.
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609. Patrap 20:55 GMT le 18 juillet 2009    
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
Member Since: 3 juillet 2005 Posts: 377 Comments: 113004
610. HadesGodWyvern 20:56 GMT le 18 juillet 2009    
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
Member Since: 24 mai 2006 Posts: 43 Comments: 36940
611. IpswichWeatherCenter 20:56 GMT le 18 juillet 2009    
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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612. hunkerdown 20:58 GMT le 18 juillet 2009    
Quoting IpswichWeatherCenter:


97L is still an invest, somehow.
dropped
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613. Cavin Rawlins 20:58 GMT le 18 juillet 2009    
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: 24 juillet 2005 Posts: 407 Comments: 19076
614. Patrap 20:58 GMT le 18 juillet 2009    
97 has been removed from the NOAA Page as well.


Atlantic and Caribbean Tropical Satellite Imagery

Das Kaput.

Member Since: 3 juillet 2005 Posts: 377 Comments: 113004
615. weatherwatcher12 21:00 GMT le 18 juillet 2009    
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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616. Patrap 21:01 GMT le 18 juillet 2009    
WB from the netherworld 456
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617. BurnedAfterPosting 21:01 GMT le 18 juillet 2009    
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
618. K8eCane 21:01 GMT le 18 juillet 2009    
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
Member Since: 26 avril 2006 Posts: 5 Comments: 2496
619. stormwatcherCI 21:01 GMT le 18 juillet 2009    
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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620. MasterOfStorms 21:01 GMT le 18 juillet 2009    
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.
621. Patrap 21:02 GMT le 18 juillet 2009    
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622. GeoffreyWPB 21:02 GMT le 18 juillet 2009    
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!
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623. WxLogic 21:02 GMT le 18 juillet 2009    
WB... 456
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624. alaina1085 21:03 GMT le 18 juillet 2009    
Welcome back 456!
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625. Patrap 21:03 GMT le 18 juillet 2009    
626. wunderkidcayman 21:04 GMT le 18 juillet 2009    
A Big Welcome Back 456!
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627. GeoffreyWPB 21:04 GMT le 18 juillet 2009    
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.
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629. Cavin Rawlins 21:05 GMT le 18 juillet 2009    
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.
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630. Patrap 21:05 GMT le 18 juillet 2009    
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632. Patrap 21:08 GMT le 18 juillet 2009    
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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633. reedzone 21:09 GMT le 18 juillet 2009    
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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634. afj3 21:09 GMT le 18 juillet 2009    
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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635. Cavin Rawlins 21:10 GMT le 18 juillet 2009    
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: 24 juillet 2005 Posts: 407 Comments: 19076
636. stormwatcherCI 21:10 GMT le 18 juillet 2009    
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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637. afj3 21:11 GMT le 18 juillet 2009    
Quoting stormwatcherCI:
Yes.

Thanks!
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638. Patrap 21:11 GMT le 18 juillet 2009    
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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639. Cavin Rawlins 21:11 GMT le 18 juillet 2009    
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.

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640. Cavin Rawlins 21:14 GMT le 18 juillet 2009    
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641. Patrap 21:14 GMT le 18 juillet 2009    
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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642. wunderkidcayman 21:15 GMT le 18 juillet 2009    
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643. Cavin Rawlins 21:15 GMT le 18 juillet 2009    
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: 24 juillet 2005 Posts: 407 Comments: 19076
644. Patrap 21:17 GMT le 18 juillet 2009    
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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645. AllStar17 21:17 GMT le 18 juillet 2009    
456

What are your thoughts on Ex 97L as it enters the "sweet spot" near the Antilles?
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646. stormwatcherCI 21:18 GMT le 18 juillet 2009    
If the invest currently over the islands were to develop what kind of track can we expect ?
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647. AllStar17 21:18 GMT le 18 juillet 2009    
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
Member Since: 29 juin 2009 Posts: 13 Comments: 5145
648. CUBWF 21:18 GMT le 18 juillet 2009    
I think the new broad area of circulation is around 11n 63.5w
649. hunkerdown 21:19 GMT le 18 juillet 2009    
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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650. Stormchaser2007 21:19 GMT le 18 juillet 2009    
Disturbance at 101 hours on the GFS. Looks interesting.

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651. K8eCane 21:21 GMT le 18 juillet 2009    
Quoting Patrap:
Dont discount the GOM and the Front,..it has a potential for Genesis as much as anything in the Basin as well.






well Pat that looks like it could develop and affect Fla and it looks like it heads straight to where i live too. Im talkin about your cyclogenesis map of the GOM blob there. What would be the strength of that??
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About JeffMasters
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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