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 IKE:


Shear looks to be starting to lift in the Caribbean.


Ya, all of the models I have looked at have been forecasting shear to weaken in the Carribean and increase in the SF, Bahamas region.
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Very windy out there with scattered rain at the moment. Hoping it doesn't get much worse when the blob crosses us since the gusts of wind have already been fairly strong since this morning.
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Quoting 7544:


but now the new gfs takes it away from so fla go figure
true, but remember the TUTT tends to take it to the warm waters of the Bahamas, and then S-FL, this might be another Catrina if you think about it but just not a CAT 1 maybe a TS, if it does form, probably will die out, imo.
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It's really starting to pick up here. Wheeee!

HKO is reporting max gust winds for last 10 minutes at Tate's Cairn at 127 km/h and Tap Mun at 115 km/h

10 min mean Sustained winds around 90km/h
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I think what some fail to realize; and no this isnt a shot at anyone, its just to make you think

look back at how many systems that form in the Caribbean and Gulf came from tropical waves that basically go unnoticed in the Atlantic.

Look at both Dolly and Fay last season. They were both labeled invests way out in the Atlantic and both also took about a week to finally develop. There is no script when it comes to how these systems develop.
anybody from charleston sc I want to send yall something. thanks
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143. HadesGodWyvern (Mod)
Night Aussie
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Quoting BurnedAfterPosting:


meaning I doubt it is anything more than a rainmaker for SFL

that being said, we all know in Florida that just heavy rains can be a problem

Wait a minute due to the steering pattern and generally weaker storms take a western route
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Night Aussie.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Quoting Greyelf:

Odd..I've never had that problem at all. (Then again no one pays attention to anything I contribute to this blog, so why should the software running it be any different?)

Is it possible that the people having this problem are running the same browser?

I have Firefox 3.5 and i get booted
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Quoting btwntx08:

goodbye and ur on my list of ingores now won't hear from ya no more


why because he disagrees with you?
Night all.... have a good day all... and no fighting
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Quoting LightningCharmer:


It's been happening to me also. I thought it may have to do with certain advertising but I'm sure some of you are paying members so that may not be the reason.

Regarding some of the ads, when mouse-over or mouse-hover, my anti-spyware software starts alerting to potential harmful...etc.

I actually click some of the ads not just out of interest but also to support the site.

Thank you Dr. Masters for the update.
+1...I have also gotten "computer threats/possible virus warnings" on two different computers while on this blog (and both have heavy anti-virus and firewall protection).
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its my observation that a low has developed just to the west of the tropical wave near 60W look at the nw corner of the convection
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133. HadesGodWyvern (Mod)
China Meteorological Administration

** WTPQ20 BABJ 181600 ***
SUBJECTIVE FORECAST
TY MOLAVE 0906 (0906) INITIAL TIME 181600 UTC
00HR 22.5N 114.8E 965HPA 38M/S (75 kts)
30KTS 260KM
50KTS 80KM
P12HR WNW 28KM/H=
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Quoting hunkerdown:
But due to its weakness it won't head into the Caribbean.


meaning I doubt it is anything more than a rainmaker for SFL

that being said, we all know in Florida that just heavy rains can be a problem
Quoting hunkerdown:
But due to its weakness it won't head into the Caribbean.
true, i think we might have 95L or 98L tonight if the strong convection persists with this wave over the USVI, imo.
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Quoting IKE:
Dr. Masters,

Your blog is kicking me out when I hit refresh. Not every time...maybe a third of the time. It's been going on for about 2 weeks now. I have to click a couple of links to get back in.

Odd..I've never had that problem at all. (Then again no one pays attention to anything I contribute to this blog, so why should the software running it be any different?)

Is it possible that the people having this problem are running the same browser?
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129. 7544
Quoting canesrule1:
agreed, S-FL should watch this.


but now the new gfs takes it away from so fla go figure
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Quoting 7544:
due to wind shear or not it still looks better than 97l and was there before 97l ever got tagged .


looks are very deceiving, this is what I was pointing out yesterday. You have to look at the structure of the waves to determine strength, not convection

that convection with the wave at 60W sure looks good, but there is nothing really to it. 97L; while lacking convection still has a good structure to it
Quoting moonlightcowboy:


Yup, and 97L is moving west or maybe swest and could slide in above Trinidad under the worst part of the shear.

That could mean trouble for the Greater Antilles.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
125. IKE
Quoting nrtiwlnvragn:
CIMSS updating again




Shear looks to be starting to lift in the Caribbean.
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Quoting Acemmett90:

it allready is yellow
i mean orange.
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Quoting BurnedAfterPosting:


shear wont be favorable if it takes that path; when the TUTT splits and creates the favorable conditions in the Caribbean, that unfavorable shear will lift north of the Islands. If that wave at 60W wants to survive it needs to go into the Caribbean.
But due to its weakness it won't head into the Caribbean.
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Quoting BurnedAfterPosting:
looking at the 2 systems it is easy to be fooled by the convection

97L is still the more organized of the two waves, again the area at 60W has flared up due to the waves interaction with the TUTT and hostile wind shear.



Yup, and 97L is moving west or maybe swest and could slide in above Trinidad under the worst part of the shear.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
Quoting IKE:
Dr. Masters,

Your blog is kicking me out when I hit refresh. Not every time...maybe a third of the time. It's been going on for about 2 weeks now. I have to click a couple of links to get back in.


It's been happening to me also. I thought it may have to do with certain advertising but I'm sure some of you are paying members so that may not be the reason.

Regarding some of the ads, when mouse-over or mouse-hover, my anti-spyware software starts alerting to potential harmful...etc.

I actually click some of the ads not just out of interest but also to support the site.

Thank you Dr. Masters for the update.
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Quoting hunkerdown:
True, but due to its current weakness it will tend to head toward SFla and who knows what happens when it hits the very warm Bahama waters (probably nothing but should just keep one eye open).
agreed, S-FL should watch this.
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Quoting canesrule1:
no because this blob will probably die out, but it will give a moist path for 97L and give it a window for tropical formation.
the fire for the match
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115. 7544
due to wind shear or not it still looks better than 97l and was there before 97l ever got tagged .
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CIMSS updating again


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Quoting canesrule1:
I dont think the NHC will go yellow with the second wave over the USVI, they'll go yellow with it if it is still going strong at 8 EST, imo.
Its already yellow.
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Quoting hunkerdown:
True, but due to its current weakness it will tend to head toward SFla and who knows what happens when it hits the very warm Bahama waters (probably nothing but should just keep one eye open).


shear wont be favorable if it takes that path; when the TUTT splits and creates the favorable conditions in the Caribbean, that unfavorable shear will lift north of the Islands. If that wave at 60W wants to survive it needs to go into the Caribbean.
I dont think the NHC will go yellow with the second wave over the USVI, they'll go yellow with it if it is still going strong at 8 EST, imo.
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Quoting BurnedAfterPosting:
looking at the 2 systems it is easy to be fooled by the convection

97L is still the more organized of the two waves, again the area at 60W has flared up due to the waves interaction with the TUTT and hostile wind shear.

True, but due to its current weakness it will tend to head toward SFla and who knows what happens when it hits the very warm Bahama waters (probably nothing but should just keep one eye open).
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Thanks Ike, Will do.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
its on the NHC site because it is still a tropical wave, and there is a small chance it survives until wind shear relaxes.

In reality though the flare up of convection is due more to the wind shear than anything else

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oh Admin are you evere going too get this fixs

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Quoting MrstormX:
Forget 97L for now maybe days in the future but not now, the unnamed wave looks a little better
no because this blob will probably die out, but it will give a moist path for 97L and give it a window for tropical formation.
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looking at the 2 systems it is easy to be fooled by the convection

97L is still the more organized of the two waves, again the area at 60W has flared up due to the waves interaction with the TUTT and hostile wind shear.

Masters referred to it as 2nd wave.
Member Since: August 10, 2007 Posts: 0 Comments: 3278
Quoting BurnedAfterPosting:
the wave at 60W is blowing up due to wind shear and nothing else




oh you sure
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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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