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 jurakantaino:
"Burnedafterpoiting" is the only person here that have forecast this system correctly so far. Even when they were driving him crazy!


Thank you for the props, but I am not the only one who got it right.

I felt it was very important yesterday for it to be noted the difference between 97L and the wave at 60W. Many seemed in awe of the pretty colors on satellite with the wave at 60W, tropical systems are much more complicated than just pretty colors lol
good to see you back 456. i know it is early but what direction do you think this thing will take? what i am asking is there a good chance it will find it's way into the gulf?
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1998. Drakoen
Quoting IKE:


It could be. I've thought that a few times in 2009.

I never RIP-ed 97L because the system out ahead of it did the same thing...fading and coming back.

I notice that system further west appears headed south of DR and Haiti....



I never ripped it either.
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1997. aquak9
1989, savanahstorm- I know you are very right, guess I'm old school, I like to go thru vis one frame at a time, back and forth, and see the cloud layers.

Really helps me when it's early or late in the day, sun's bigger angle helps me see the shadows better, and in my mind I can visualize height and depth better.
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1996. WxLogic
I've combined the latest 850MB through 500MB VORT charts just to show the 2 systems NHC is tracking and to display how they stack up throughout these layers.

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Quoting surfmom:


MEEEEEE TOO!.... and maybe a taste of groundswell --been a long time.


LOL Been waiting for this reaction from you. Surfs almost up!!! uhhh maybe :)
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Thanks nrti and good morning

Not what I wanted to hear...I am not a big fan of data latency... :~)
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1993. IKE
Quoting HURRICANECAT5:
How far north is shear suppose to go? Will it lift out completely of the eastern and western carribbean?


Eastern Caribbean...it looks to be heading to 10-20 knots of shear right now(it could be less). It wouldn't rip it apart like the wave further west.
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"Burnedafterposting" is the only person here that have forecast this system correctly so far. Even when they were driving him crazy!
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Quoting aquak9:
thanks, SJ and 456.

When looking for inverted V sigs, I often try at the early morning hours, right after DMAX, even tho there are less visible sats to look at, seems to be the best time to catch them.

The red and green lines on your post, 456, are very helpful to me, and that's exactly what I was trying to see. Much easier to see a graph/axis separation of the storm, makes it much easier for me to separate each quadrant and look at it objectivley.


yea, i have been studying tropical waves about 10 years now and I find it simplier to understand when you stop, pause and draw lines.
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1990. fire635
Quoting surfmom:


we should concentrate on improving Human Nature b/4 we mess w/Mother Nature.....as much as I do not like "canes, I can't help but think they play a role in the NATURAL ORDER of things and don't believe they should be messed with. Considering how we've blundered in the past making corrections --the money would be better spent fixing all the disasters Army Corp of Engineers already created or needs to be fixed.
ICW
NOLA Levees
LAKE OKEECHOBEE LEVEE'S
Midnight Pass, Siesta Key

Bill Gates should leave MotherNature alone and keep his hands on his own MotherBoard.


I AGREE 100%. The devestation these storms can sometimes cause are quite hard to take, but I believe they are a VERY important part of the way mother nature takes care of her planet.
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Quoting aquak9:
another question- trying hard to find inverted V sig on visible, am I trying too hard or am I seeing it on the east, southeast area of 97L?


Inverted V is always easier to see on precipitable water imagery than on visible.

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Quoting StormJunkie:
Never mind on the link 456, I am there all the time and just forgot/overlooked the fact that the next pass times were right next to the snake bite kit...

doh!


You will need to add data latency time to those overpass times, which can be up to 4 hours. Satellite has to pass over a ground station to download the data.
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Where is Levi when you need him...arggg.
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How far north is shear suppose to go? Will it lift out completely of the eastern and western carribbean?
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1985. aquak9
thanks, SJ and 456.

When looking for inverted V sigs, I often try at the early morning hours, right after DMAX, even tho there are less visible sats to look at, seems to be the best time to catch them.

The red and green lines on your post, 456, are very helpful to me, and that's exactly what I was trying to see. Much easier to see a graph/axis separation of the storm, makes it much easier for me to separate each quadrant and look at it objectivley.
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There is nothing to stop this from forming.Its entering warmer sea surface temps/shear is decreasing each day/and its in 5 to 10kt shear right now.Plus tstms keep on forming.
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1983. IKE
Quoting extreme236:


Not to jump the gun on this, but I really think this could be our first named storm this season.


It could be. I've thought that a few times in 2009.

I never RIP-ed 97L because the system out ahead of it did the same thing...fading and coming back.

I notice that system further west appears headed south of DR and Haiti....
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Shear Tendencies
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Quoting StormJunkie:
Thanks 456 and morning

Can you repost that link? Didn't seem to come through.


Ok, go to the navy site and slect 97L, you should see it there at the bottom.


DDR,

If you use Opera and Firefox browser they reduce images to a standdard size to prevent blog stretching
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HOW FAR NORTH IS THE SHEAR SUPPOSE TO GO? WILL IT LIFT COMPLETELY OUT OF EASTER AND WESTERN CARRIBBEAN?
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Never mind on the link 456, I am there all the time and just forgot/overlooked the fact that the next pass times were right next to the snake bite kit...

doh!

We are about 3 hours away from the TRMM and AQUA passes. Hopefully they get a good look...and the experts start re-centering the imagery over the system.
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Quoting IKE:
Looks like they need to raise the odds from under 30%, up a notch.


Yup, exactly.
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Quoting IKE:
Shear continues lifting north in the eastern Caribbean....



Not to jump the gun on this, but I really think this could be our first named storm this season.
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1976. IKE
Looks like they need to raise the odds from under 30%, up a notch.
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Quoting HurricaneSwirl:


I agree. They ONLY care about the u.s. ivan was a cat 3 hitting the islands and a 4/5 hitting jamaica and the caymans and they only cared about it once it got into the gulf pretty much.

I dont think they covered paloma or omar at all, but i cant remember. They knew it wasn't going to affect the united states so apparently it didnt matter if a cat 4 hits cuba or the windward islands. (actually i think omar made a direct hit on the u.s. virgin islands but im not sure)
I think you are right about Omar. With Ivan my father who lives outside Tampa said the thing that po'd him the most about TWC was no mention of the Cayman Islands.
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Quoting aquak9:
another question- trying hard to find inverted V sig on visible, am I trying too hard or am I seeing it on the east, southeast area of 97L?


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1973. IKE
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Quoting aquak9:
another question- trying hard to find inverted V sig on visible, am I trying too hard or am I seeing it on the east, southeast area of 97L?


Morning Aqua

I was thinking the same thing...But like Drak said, we don't have enough visible to tell yet...And we all know how these weak circulations like to let the center jump all around.
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Thanks 456 and morning

Can you repost that link? Didn't seem to come through.
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1970. DDR
Quoting Weather456:


link

Thanks,one problem though,the animations are smaller than the one you posted.any idea why?
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1969. IKE
Shear continues lifting north in the eastern Caribbean....

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1968. aquak9
another question- trying hard to find inverted V sig on visible, am I trying too hard or am I seeing it on the east, southeast area of 97L?
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1967. SLU
Quoting Weather456:
SLU, I have become accustom to ppl forgeting about the islands, but over the years I don't see it as much.

The worst ever was Hurricane Emily, Hurricane Dean and Hurricane Felix. Some did not give those the storm much attention (all cat 5) compared to barely cat 1 Humberto.


which is why we must continue to monitor our own weather over the internet!
Member Since: July 13, 2006 Posts: 12 Comments: 4734


look at that outflow..
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting StormJunkie:
people were RIPing it to death, and today it is a totally different story.

People, including the NHC, were "rip'ing" it yesterday because it deteriorated to a very weak wave at best. But as BAP said, this is part of what makes the "tropicals" so interesting.

Ok, next question for the experts...

Is there any where to view a schedule of when the Navy microwave imagery updates?


Yea

Go here

look down and you'll see a table showing Pass_info showing each sensor, the current and next pass

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Quoting surfmom:


we should concentrate on improving Human Nature b/4 we mess w/Mother Nature.....as much as I do not like "canes, I can't help but think they play a role in the NATURAL ORDER of things and don't believe they should be messed with. Considering how we've blundered in the past making corrections --the money would be better spent fixing all the disasters Army Corp of Engineers already created or needs to be fixed.
ICW
NOLA Levees
LAKE OKEECHOBEE LEVEE'S
Midnight Pass, Siesta Key

Bill Gates should leave MotherNature alone and keep his hands on his own MotherBoard.


Hey Surfmom!

And good morning/afternoon to everyone else.

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people were RIPing it to death, and today it is a totally different story.

People, including the NHC, were "rip'ing" it yesterday because it deteriorated to a very weak wave at best. But as BAP said, this is part of what makes the "tropicals" so interesting.

Ok, next question for the experts...

Is there any where to view a schedule of when the Navy microwave imagery updates?
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Quoting DDR:
456 where did you get that satellite animation?
could you post a link please?


link
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1961. surfmom
Quoting BenBIogger:
Stu Ostro his response on Bill Gates plan to control hurricane

Can Bill Gates control hurricanes?



we should concentrate on improving Human Nature b/4 we mess w/Mother Nature.....as much as I do not like "canes, I can't help but think they play a role in the NATURAL ORDER of things and don't believe they should be messed with. Considering how we've blundered in the past making corrections --the money would be better spent fixing all the disasters Army Corp of Engineers already created or needs to be fixed.
ICW
NOLA Levees
LAKE OKEECHOBEE LEVEE'S
Midnight Pass, Siesta Key

Bill Gates should leave MotherNature alone and keep his hands on his own MotherBoard.
Member Since: Posts: Comments:
850 mb Vorticity
Member Since: June 29, 2009 Posts: 13 Comments: 5238
Quoting AllStar17:


Thus, probably a WNW or NW motion will occur.


Allstar, I think you're right. 97L, as it moves into the eCaribbean, will finally detach itself from the ITCZ. As it begins to strengthen, coriolis alone, will advance the system initially two degrees more northward.
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Shear continuing to fall at a rapid clip in front of 97L

Member Since: June 29, 2009 Posts: 13 Comments: 5238
1957. Drakoen
Quoting adrianalynne:
So I'm guessing we get GFDL and HWRF runs on the 12.? Or do you think they will wait? Do we know the exact LLC Lat/Lon location?


There's a chance they may be run at 12z considering how early the BAM guidance came out.
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1956. DDR
456 where did you get that satellite animation?
could you post a link please?
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So I'm guessing we get GFDL and HWRF runs on the 12.? Or do you think they will wait? Do we know the exact LLC Lat/Lon location?
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Quoting moonlightcowboy:
97L will continue to move mostly west - every steering layer is showing a westerly flow. If it continues on its present course it should cross the windwards near Barbados, the island on point, and then move into the eCaribbean. As the TUTT lifts out I'm guessing that we'll some shift in the steering more northwards, but most of that has been at the higher levels anyways - unless 97L gains some steam that steering would hardly effect it and it will still move more west than north.


Thus, probably a WNW or NW motion will occur.
Member Since: June 29, 2009 Posts: 13 Comments: 5238
1953. Drakoen
GOES only has about 7 frames of light images. Need more to determine anything at the surface right now I still suspect a well-defined mid level circulation. The 850mb vort maximum still needs to deepen.
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Quoting leftovers:
once i looked trying to find a email responce to twc couldnt. they dont realise how many people are out there loving their tropical updates


You like their tropical updates?? I don't because they give just general information to the public. I never see them go above and beyond...it is just general info. I do like their coverage when a storm is threatening the US...I also like their "Storm Alert mode".
Member Since: June 29, 2009 Posts: 13 Comments: 5238
97L will continue to move mostly west - every steering layer is showing a westerly flow. If it continues on its present course it should cross the windwards near Barbados, the island on point, and then move into the eCaribbean. As the TUTT lifts out I'm guessing that we'll see some shift in the steering more northwards, but most of that has been at the higher levels anyways - unless 97L gains some steam that steering would hardly effect it and it will still move more west than north.
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Station 41097
Meteo France
Location: 14.54N 61.09W
Conditions as of:
Sun, 19 Jul 2009 12:46:00 UTC
Water Temperature: 85.6 F
Member Since: March 19, 2009 Posts: 0 Comments: 1419

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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.