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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500. Skyepony (Mod)
The new invest is a NOAA declared invest, Navy should name it soon or waiting for 97L to get tangled in it. They don't always agree. Usually don't see waves combine. That one at 60 looks like it has hit a wall while 97L Keeps treking fast. Interesting is the N edge bit of the 60W blob convection..maybe ULL about to form there just W of there
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Quoting nrtiwlnvragn:
invest_DEACTIVATE_al972009.ren


The switch is pulled. See ya 97L.
Member Since: July 7, 2005 Posts: 0 Comments: 5351
And I'm not wearing black.
Member Since: September 10, 2007 Posts: 0 Comments: 11278
Quoting nrtiwlnvragn:
invest_DEACTIVATE_al972009.ren


Looks like the plug has been pulled.
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Quoting nrtiwlnvragn:
invest_DEACTIVATE_al972009.ren


bye bye 97L
Quoting BurnedAfterPosting:


usually a sign the thunderstorms are about to collapse


Yep...convection should begin to wane significantly.
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Structure is still impressive and THERE IS convection on 97L, but not deep convection, that might happen late tonight though. Shear took a drastic drop in the Carribean to 5 knots in some areas. This is good for 97L. I definitely see a new spin with convection with 97L, it's not done yet folks, I think this is starting to get into a moist environment and it's actually looking good right now. Look for a circulation near and around 47W and 11N

http://rammb.cira.colostate.edu/ramsdis/online/latest_image_640.asp?product=tropical_ge_4km_ir4_flo ater_1
Member Since: July 1, 2008 Posts: 13 Comments: 7396
invest_DEACTIVATE_al972009.ren
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Quoting FloridaTigers:
I don't get this blog at times. Why do so many people in S. Florida think every blob is a hurricane threat to Miami? Do we need to add to the NOLAcasters?


Because they want it to hit S.FL because thats where they live..lol.
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On another topic, many were wondering why we jumped to 97L instead of 95. Could it be that 95 and 96W were in the Western Pacific and to avoid confusion, the NHC went to 97?
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490. CUBWF
Well, I think one of this waves are going to be like the marlins, runs at the last inning. lol
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Quoting chsweatherintern2009:
if you look at the goes noaa sat we page it says invest


Nothing yet on the Navy site. I take it you mean Atlantic?
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Quoting Stormchaser2007:
Outflow boundaries coming out of the Antilles TUTT enhanced wave.



usually a sign the thunderstorms are about to collapse
Quoting chsweatherintern2009:
if you look at the goes.noaa sat web page it says invest


Its not an official invest though. Just something to monitor for the time being.
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Quoting StormJunkie:
Thanks for the update Skye...

This NOAA shifting the floater says a lot...at least for the time being.



Hi Stormjunkie,
Maybe NOAA thinks the wave out in front might have better advantage of Caribbean lower shear?
Member Since: July 7, 2005 Posts: 0 Comments: 5351
Quoting chsweatherintern2009:
if you look at the goes noaa sat we page it says invest


we have seen that about 3 times this year where they did that and no new invest was ever declared
Outflow boundaries coming out of the Antilles TUTT enhanced wave.

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I don't get this blog at times. Why do so many people in S. Florida think every blob is a hurricane threat to Miami? Do we need to add to the NOLAcasters?
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if you look at the goes.noaa sat web page it says invest
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Thanks for the update Skye...

This NOAA shifting the floater says a lot...at least for the time being.

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Quoting CUBWF:
I think 97L it's not dead. Remember the A and K storm at one time they both looks like this. Weather is like beisboll game. Nothing is said and done until the last out.


Unless you play for the Nationals or Mets ;)
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Quoting BurnedAfterPosting:


that is due to the TUTT moving out of the Caribbean, where the drastic decrease occurs, it has to show a drastic increase somewhere


Yep, I know that...just interesting to see.
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Latest 850 millibar vorticity
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we never really have seen a hurricane here in SE florida since 2005, so if pretty soon something will come our way, it might be 97L or the other wave (Though im not seeing a very high chance of these systems developing too soon), We may have to keep a close eye on these disorganized, but decent-looking disturbances.
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Quoting chsweatherintern2009:
NEW INVEST


There is no invest. Its just labeled as an AOI.
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Quoting BurnedAfterPosting:


hmmmmmm so maybe the two waves do combine in some way?


So new Invest then?
Member Since: July 7, 2005 Posts: 0 Comments: 5351
Quoting Stormchaser2007:


Yet increasing by 30knots over the greater Antilles. Interesting.


that is due to the TUTT moving out of the Caribbean, where the drastic decrease occurs, it has to show a drastic increase somewhere
NEW INVEST
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Quoting Skyepony:
NOAA took the floater off 97L & put it on invest ( the big blob in front of 97L).. It's pretty stationary with the 97L wave moving quickly toward it. I give this a pretty good chance of pulling it together.


hmmmmmm so maybe the two waves do combine in some way?
Quoting weatherwatcher12:


Drastic drop


Yet increasing by 30knots over the greater Antilles. Interesting.
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470. CUBWF
I think 97L it's not dead. Remember the A and K storm at one time they both looks like this. Weather is like beisboll game. Nothing is said and done until the last out. Dry air is diminishing litle by litle. Now moisture from wave 2 is helping it to keep her alive. Will see if it can maintaing some convection after dmin. and increase its circulation.
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469. Skyepony (Mod)
NOAA took the floater off 97L & put it on invest ( the big blob in front of 97L).. It's pretty stationary with the 97L wave moving quickly toward it. I give this a pretty good chance of pulling it together.
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Drastic drop west of the islands
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18Z shear



18Z shear tendency
shear continues to decrease as of 18Z
465. SLU
Quoting stoormfury:
good afternoon SLU

you are so correct with your analysis. i made that analyais a few hours ago just before 456 did his thing on futuremet post. st lucia was having west winds since 10. 30 am and i made that observation abd suggested that a surface low maybe forming


What's up fury

Yeh I experienced those light west winds this morning. Nothing much though. Had it not been for the shear, this could have been a real strong disturbance by now. 97L looks very ill but I believe it will blow up as it approaches the islands on Monday. This has been the general pattern this year.
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yea that is from earlier this morning, the descending pass wont be out for a few hours
463. CUBWF
Hi Stormpetrol, I think everything is gona change for us next week.
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Invest 97L
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latest 332 pm edt
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Only NHC can pull the switch on 97L no matter what the RIP count is on a blog lol :)
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quikscat
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443.

I agree with most everything you said BAP...


I think where we differ a little in opinion is here...

I am not sure that we have an idea of what the structure of the 60w wave looks like. No Quickscat this morning, covered in convection so we can't see, and it has maintained convection for 24hrs, TUTT enhanced or not.

It also seems that both waves will have to fight off at least some shear over the next 24-72hrs. So the one that has the better structure headed in to the shear would be the better bet...Or at least I think that may be what the models are picking up on.

I did not sleep at a Holiday Inn Express last night! Been wrong before, and will do it again.

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Quoting canesrule1:
wtf did u write, LOL


It's french.

And roughly, it's looking like its going to rain pretty heavily in the antillies soon.
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Quoting CUBWF:
Thanks Ike. We need some rain is sw Miami. It's very hot and dry with all that saharan dust over us.


No thanks dude. I'll just stay in doors. Outside of this week, its been pouring non stop all summer.
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Quoting CUBWF:
Thanks Ike. We need some rain is sw Miami. It's very hot and dry with all that saharan dust over us.

Need some rain here real bad in the Caymans also, the haze from the dust is terrible.
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Quoting StormJunkie:
441...

Not pointing out things that I think are "wrong" just things I view differently...Which should lead to discussion/debate with folks that have a different point of view..desired out come...We learn.


Sorry for the remark, got a little jumpy lol. I know nothing is 100 or 0%, i was just kinda emphasizing how dead i thought it would be. ill take your point of view into consideration, too
Member Since: July 7, 2008 Posts: 2 Comments: 3237
the wave at 60W looks like a scared cat with its hair all standing up LOL
452. CUBWF
Thanks Ike. We need some rain is sw Miami. It's very hot and dry with all that saharan dust over us.
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Here in Puerto Rico winds at 25mph gusting to 35mph,,,,
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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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