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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Quoting Drakoen:


Post 665, 668, and 691
Could you please be more clear :)
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Quoting MasterOfStorms:
97l will refire storms tonight.




its not 97L its called x-97L
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Quoting Drakoen:
Ex-97L looks to the racing the the convective mass. I would still watch and as it could interact with the southern portion of the wave axis ahead of it and possibly get things going in the Caribbean.
Do you think there is a possibility of this happening ?
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Quoting Seflhurricane:
drak what analysis do you give about these 2 systems your opinion


Post 665, 668, and 691
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Well,..Lord help the masses,..LOL

A circulation is evident west of the Leewards already in the Caribbean,..the Blow up of Convection is east of it.

Floater 1 - Visible Loop
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Quoting Tazmanian:



its not 97L
Taz, there is a small burst firing at ex97L.
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Quoting Drakoen:
Ex-97L looks to the racing the the convective mass. I would still watch and as it could interact with the southern portion of the wave axis ahead of it and possibly get things going in the Caribbean.
drak what analysis do you give about these 2 systems your opinion
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Ex-97L looks to the racing the the convective mass. I would still watch and as it could interact with the southern portion of the wave axis ahead of it and possibly get things going in the Caribbean.
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Quoting Patrap:
If one is Running FF3 and having wu problems,restart and reboot you system.
A fix is in by FF3.


Upgrade to FF 3.5
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If one is Running FF3 and having wu problems,restart and reboot you system.
A fix is in by FF3.
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97l will refire storms tonight.
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Quoting GeoffreyWPB:
We have 98L? And this blog is still acting crazy, tech. wise. and welcome back Drak.


Yea. I had to click the blog link 3 back and forth times for the actual blog to show up.
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Quoting AllStar17:


Wouldn't that be eerie. Alex in 2004 formed and rode along the east coast during its lifetime....now in 09 there is the potential for a possible Ana to move along the same pathway.


I was looking the genesis of Alex earlier today, and some similarities, but I wouldn't put too much into it.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting MasterOfStorms:
Tstms starting to fire on the west side of 97l



its not 97L
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Glad to be back though nothing imminent in the tropics.
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We have 98L? And this blog is still acting crazy, tech. wise. and welcome back Drak.
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Quoting weatherwatcher12:

It could go through the Caribbean and end up in Mexico also. The Caribbean is favorable.
That's what I am afraid of.
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welcome back drak :)
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Quoting weatherwatcher12:

If it goes into the Bahamas it wil get sheared because of the TUTT


The will be in a different area by then, this is a little over 100 hours.
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Quoting Drakoen:
Shear in the Bahamas looks to stay unfavorable. An east coast storm has a better chance a being a subtropical entity as it interacts with a frontal boundary and an upper level trough.
Welcome back.
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Quoting Funkadelic:


But the only place for it to go, would be florida, or into the gulf of mexico.. Because if it goes north of bahamas, it would get destroyd by the TUTT

It could go through the Caribbean and end up in Mexico also. The Caribbean is favorable.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Tstms starting to fire on the west side of 97l
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justlogged back in what is new with ex97L and the new invest near the islands how is the wind shear
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Blog Update
Reflector site for those at work, which includes Weather456, daily update, and the update on the update... sheesh he should just write a new one.
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WB... Drak... hehe
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Quoting Funkadelic:


But the only place for it to go, would be florida, or into the gulf of mexico.. Because if it goes north of bahamas, it would get destroyd by the TUTT
What if it stays in the Caribbean ?
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Does anyone know when the shear is suppossed to relax to favorable conditions?
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Shear in the Bahamas looks to stay unfavorable. An east coast storm has a better chance a being a subtropical entity as it interacts with a frontal boundary and an upper level trough.
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667. CUBWF
Is the wave at the antilles moving faster than in the morning? If it's like that, will be under the higher sher and development will be less likely.
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New floater

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting reedzone:
I'm giving 97L about 14 hours, if it's not going to blow up tonight, I'm done with it. As for the wave near the Islands, that's a different story. Shear is 50 knots over the area right now, but according to models, shear will subside and allow slow development on this particular feature. Development will be around 40% chance when or IF it enters the Bahamas, I think if it can make it north of the Carribean, I can see our first named storm form and threaten the Southeastern and possibly the Northeast Coastline. The conditions might just get there for it, we'll have to wait and see.


Wouldn't that be eerie. Alex in 2004 formed and rode along the east coast during its lifetime....now in 09 there is the potential for a possible Ana to move along the same pathway.
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Quoting reedzone:
I'm giving 97L about 14 hours, if it's not going to blow up tonight, I'm done with it. As for the wave near the Islands, that's a different story. Shear is 50 knots over the area right now, but according to models, shear will subside and allow slow development on this particular feature. Development will be around 40% chance when or IF it enters the Bahamas, I think if it can make it north of the Carribean, I can see our first named storm form and threaten the Southeastern and possibly the Northeast Coastline. The conditions might just get there for it, we'll have to wait and see.

If it goes into the Bahamas it wil get sheared because of the TUTT
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Your next best bet at a Depression
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Quoting Patrap:
The circ is west of the Islands with that Cloud Mass and blow up behind it.



Easily seen on the Long Vis FLoater 1

There also appears a burst on the rainbow where you see the rotation on the visible.
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There is no Mo 97L,there is a Cloud mass that was 97L,but it isnt a entity anymore.
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I'm giving 97L about 14 hours, if it's not going to blow up tonight, I'm done with it. As for the wave near the Islands, that's a different story. Shear is 50 knots over the area right now, but according to models, shear will subside and allow slow development on this particular feature. Development will be around 40% chance when or IF it enters the Bahamas, I think if it can make it north of the Carribean, I can see our first named storm form and threaten the Southeastern and possibly the Northeast Coastline. The conditions might just get there for it, we'll have to wait and see.
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If 97 makes it to 50w does it have a chance to develope?
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The circ is west of the Islands with that Cloud Mass and blow up behind it.



Easily seen on the Long Vis FLoater 1

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Quoting AllStar17:
456

What are your thoughts on Ex 97L as it enters the "sweet spot" near the Antilles?


I'm not surprise that they deactivated 97L becuz it's pretty much doing nothing as it head west. There is little change in struture and it would not develop convection. However, invests have been dropped and re-designated, especially in the Western TRP ATL and as I stated in my update this morning, 97L may go through the same fate as the tropical wave right now (blow up in convection). One way to think of it is that the wave near the Antilles had look like 97L when it was at 40-50W. If it does so, then I would monitor for development, but otherwise, it will become a lost invest.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I see 97L is dying out. The area near the Lesser Antilles is interesting with an 850mb vorticity maximum. The GFS forecasts for shear to drop in the Caribbean over the next 48 to 72 hours which may allow for some development if the system can stay together. The GFS shows the upper level anticyclone center just northeast of Panama with the upper ridge axis extend up to the Greater Antilles. The GFS has the northern portion of the wave axis with the 85omb maximum moving just north of Hispaniola.
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Quoting AllStar17:


Especially in that water


I believe what 456 was saying is that trough split would interact with the tropical wave and create development
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Short Floater 1 - Visible Loop
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Quoting AllStar17:
456

What are your thoughts on Ex 97L as it enters the "sweet spot" near the Antilles?
If the ball hits the true sweet spot, I'd say a round tripper...oh wait a minute, never mind, thats baseball.
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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.






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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Disturbance at 101 hours on the GFS. Looks interesting.

Member Since: June 9, 2007 Posts: 4 Comments: 15889

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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.