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 Joanie38:
Good morning everyone!!!

Welcome back 456...good to see you..:)

Joanie


Morning, thanks.
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Morning Joanie :)
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what are the exact coordinates for 97L reborn so I can plot it on my map please?
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Quoting IKE:
If it's moving at 23 mph, it will be approaching the islands tomorrow.


Morning IKE!

You should of been on here last night. I and 2 others were the only ones giving 97L hope for regeneration.
Member Since: July 1, 2008 Posts: 13 Comments: 7396
Still not too well organize on Microwave imagery a curve band evident.

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Good morning everyone!!!

Welcome back 456...good to see you..:)

Joanie
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Quoting reedzone:
And as I predicted Invest 97L has returned! YAY

I knew this would make a comeback last night, conditions were favorable. For all those who said I was over hyping.. (sticks tongue out at you)


You totally stuck to your guns and called it!
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Quoting reedzone:
And as I predicted Invest 97L has returned! YAY

I knew this would make a comeback last night, conditions were favorable. For all those who said I was over hyping.. (sticks tongue out at you)
I was trying to remember who said that last night. I guess you were right so those who were down on you for it owe you an apology.
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Quoting reedzone:
And as I predicted Invest 97L has returned! YAY

I knew this would make a comeback last night, conditions were favorable. For all those who said I was over hyping.. (sticks tongue out at you)


LOL...
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And as I predicted Invest 97L has returned! YAY

I knew this would make a comeback last night, conditions were favorable. For all those who said I was over hyping.. (sticks tongue out at you)
Member Since: July 1, 2008 Posts: 13 Comments: 7396
Quoting pottery:
You are right, Stormwatcher.
But the ground here is still pretty hard, and the cisterns have not filled as yet ( about 1/2 full now).
Today, I need to arm myself with a cutlass, bow saw, and stuff, and follow the wifes instructions in the garden before it gets too hot.
Lots of things need cutting back, carting away, and replanting.
Going to be a sweaty one...
Take it easy and remember to rehydrate(water not a cold Coors).
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hurricane allen in 1980 was in the same position and and was moving at the same 23 mph andexploded about 53-54 w
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1787. pottery
You are right, Stormwatcher.
But the ground here is still pretty hard, and the cisterns have not filled as yet ( about 1/2 full now).
Today, I need to arm myself with a cutlass, bow saw, and stuff, and follow the wifes instructions in the garden before it gets too hot.
Lots of things need cutting back, carting away, and replanting.
Going to be a sweaty one...
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97L is moving about 19 mph

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1785. DDR
Quoting stormwatcherCI:
I agree with you 100%. I forget which storm it was that hit I think Trinidad a couple years back and they waited until the last minute to upgrade it. It did quite a bit of damage and I think there were some deaths too.

Most people from here know about Flora in 1963,Slammed tobago hard,18 deaths there and 2 deaths in Trinidad,Theres alma in 1974,1 death.Then theres arther and fran in the 90's.
Tropical storm are rare here but they do occur,we usually just get the drenching feeder bands.
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Based on SHIPS shear is going to be an issue. That is based on BAMM track, so if it does not follow BAMM shear may be different. Looking at 06Z GFS shear it looks like northly shear tracks westward through the carribean in time.
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Quoting stormdude77:
97L's forward speed might be it's own enemy....


Agreed. A bit slower forward speed would assist with the development of the circulation. At this clip it might take a bit longer to organize properly
I think it was error to with the EPAC. The last invest in the EPAC was 96E.
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1781. IKE
If it's moving at 23 mph, it will be approaching the islands tomorrow.
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Invest 97L, only invest in the deep tropics so far

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Quoting pottery:
Good morning. From Trinidad.
Woke up to a gentle, brief drizzle.
Left every leaf in the garden covered in sparkling emeralds.
What a sweet sight.
Good morning and by the looks of things I think you might have quite a bit more of those sparkling emeralds.
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Quoting Weather456:
Tropical Update
Thanks for the update and I can tell you I for one will be monitoring it closely. I don't know but I just have a "gut" feeling about this one that it will develop although no feelings about how strong it will get.
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Quoting KYhomeboy:
Hmmm...as usual it looks like the NHC is being a bit conservative. Problem with this as I've seen before is that people can be put at a disadvantage. I've seen a system look healthy but conservative decisions kept it as an invest until it was almost on top of the lesser antilles...and by then they upgraded to TS status when the system was less than 24 hours out. Doesn't give much lead time for the people to prepare. Not saying to over hype or cause panic....but the words "conservative" and "cyclone" just don't seem to belong in the same sentence.
I agree with you 100%. I forget which storm it was that hit I think Trinidad a couple years back and they waited until the last minute to upgrade it. It did quite a bit of damage and I think there were some deaths too.
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Member Since: September 23, 2005 Posts: 14 Comments: 11215
Get ready, the blogs about to explode. LOL.
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Tropical Update
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1770. centex
so we can drop the "ex"
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1769. pottery
Good morning. From Trinidad.
Woke up to a gentle, brief drizzle.
Left every leaf in the garden covered in sparkling emeralds.
What a sweet sight.
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1768. IKE
Quoting nrtiwlnvragn:
It's back

AL 97 2009071912 BEST 0 124N 502W 20 1013 DB


There's one step in the right direction!

The way this season is going, I'm surprised it's not now 95L!
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Quoting futuremet:
Wonder why the CMC and other models are expecting no development? Because they expected the Antilles wave to develop, and the other to degenerate.

12Z CMC
from yesterday


I can understand why the CMC is not forecasting development since that is the models which keeps shear high the caribbean. All the rest models decrease shear significantly in the Carib sea as the rudge builds.


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AL97 SHIPS
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Seeing the visible of ex 97L, it look MUCH better this morning then yesterday for sure. And I see the sudden burst of convection... I think it has a chance.
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It's back

AL 97 2009071912 BEST 0 124N 502W 20 1013 DB
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Wonder why the CMC and other models are expecting no development? Because they expected the Antilles wave to develop, and the other to degenerate.

12Z CMC
from yesterday
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A ball of convection now developing around the possible ''center'' near 12N

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Quoting WxLogic:


Well... trying... and GM.


Thanks.
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Hmmm...as usual it looks like the NHC is being a bit conservative. Problem with this as I've seen before is that people can be put at a disadvantage. I've seen a system look healthy but conservative decisions kept it as an invest until it was almost on top of the lesser antilles...and by then they upgraded to TS status when the system was less than 24 hours out. Doesn't give much lead time for the people to prepare. Not saying to over hype or cause panic....but the words "conservative" and "cyclone" just don't seem to belong in the same sentence.
I think the numbering issue was a mixup with the next invest number for the East Pacific with the next invest number for the Atlantic. There is not a requirement that invest numbers be sequential. Figure 4-1 from the National Hurricane Operations Plan:

Numbers 90 through 99 are reserved for tropical disturbances which have the
potential to become tropical or subtropical cyclones. Although not required, the
90’s should be assigned sequentially and reused throughout the calendar year.
Member Since: September 23, 2005 Posts: 14 Comments: 11215
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Looks like it is developing a comma shape now with the center around 12 N. I read somewhere that this signifies organization. Please correct me if I am wrong.
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1756. WxLogic
Quoting alaina1085:
Morning bloggers and bloggettes.

So from what I gather ex 97L is making a come back?


Well... trying... and GM.
Member Since: August 14, 2008 Posts: 4 Comments: 4977
Quoting SLU:


Yeh i saw it too. I believe it will weaken and the low at 12n will become the main one.


But until it does, it indicates a "disorganized" structure, just my thought.
Member Since: September 23, 2005 Posts: 14 Comments: 11215
1754. SLU
Quoting nrtiwlnvragn:
I think they are saying the vertical structure is disorganized. If you look at last nights QuikScat pass you can see a weak low level surface circulation down at 8-9N and a stronger curvature up at 11-12N. QuikScat this morning missed, but looking at visable you can see the weak LLC still down near 8-9N. At least thats my 3 cents worth.


Yeh i saw it too. I believe it will weaken and the low at 12n will become the main one.
Member Since: July 13, 2006 Posts: 13 Comments: 5259
NVRM
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1752. IKE
Quoting Weather456:


lol the whole hurricane season is messed up.

90L? Ana?
Medium probability for 93L
and where the heck was 95L and 96L.


90L/Ana...that the NHC was going to send a plane in, obviously knowing by looking at it and it's movement, that it would be on-land by the time recon got in according to the schedule posted.

Plus...the recon flight was only 100+ miles. Just go ahead and send one in earlier then scheduled.
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I think they are saying the vertical structure is disorganized. If you look at last nights QuikScat pass you can see a weak low level surface circulation down at 8-9N and a stronger curvature up at 11-12N. QuikScat this morning missed, but looking at visable you can see the weak LLC still down near 8-9N. At least thats my 3 cents worth.
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Morning bloggers and bloggettes.

So from what I gather ex 97L is making a come back?
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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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