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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1300. CUBWF
Good evening everyone. Looks ex-97 has better circlation tonight with encrease of convections. Let see if it's capable of keep it for at least 18 hours continued.
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1299. Patrap
FLoater One is still watching that Lil Surface circulation moving west Below Puerto Rico..

Run the Loop 90 percent fast and you'll see it..

Floater - RGB Color Infrared Loop

Member Since: July 3, 2005 Posts: 421 Comments: 127663
1298. WxLogic
Well good night... I'll see what I wake up to tomorrow AM as well as what 00Z models have to say.
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1297. Patrap
Banned on the run
Member Since: July 3, 2005 Posts: 421 Comments: 127663
Quoting Patrap:
I used that word once in 77,..but I forget the conversation now


LOL...
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Fun fact: Where I work, NHC NOAA meteorologists always stop by. They use the university's gym, and its only about 700 yards from the NHC itself.

Maybe I should ask them hard hitting questions like "wheres it gonna hit".
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Oops....about 1/4" here in Shoreacres today. Need more but not all at one time. Ditches still haven't been cleared well since Ike. Back in April we had two big rains that flooded houses that were just getting finished being repaired from Ike. Still lots of demo of houses going on; some really slow contractors, mostly out of state. Some seem to be more worried about filing liens than actually doing the work they contracted to do.
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How do you post animated images? eg. loops
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1292. Patrap
I used that word once in 77,..but I forget the conversation now
Member Since: July 3, 2005 Posts: 421 Comments: 127663
Quoting Drakoen:
I really don't know why SSD moved the floater to that garbage over the Lesser Antilles.


I was on the 60w bandwagon earlier Drak...Guess I was wrong there...lol... Also did not think 97l would give it a go tonight.

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1290. Patrap


Floater 1 - RGB Color Infrared Loop
Member Since: July 3, 2005 Posts: 421 Comments: 127663
1289. KEEPEROFTHEGATE (Mod)
looks like a few bloggers have been removed ace canesrule and maybe even taz

been replaced with empty space
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Quoting Patrap:
efficaciously:

ef穎i穋a穋ious (f-kshs)
adj.
Producing or capable of producing a desired effect. See Synonyms at effective.
[From Latin efficx, efficc-, from efficere, to effect; see effect.]
effi穋acious穕y adv.
effi穋acious穘ess n.


LOL

Why are you always doing that to me Pat?
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They deserve it. It was unnecessary to continue posting the site error thing. We get the point, theres blog holes. We don't need 89 different long posts repeating it.
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1286. Patrap
efficaciously:

ef路fi路ca路cious (f-kshs)
adj.
Producing or capable of producing a desired effect. See Synonyms at effective.
[From Latin efficx, efficc-, from efficere, to effect; see effect.]
effi路cacious路ly adv.
effi路cacious路ness n.
Member Since: July 3, 2005 Posts: 421 Comments: 127663
Quoting Drakoen:
I really don't know why SSD moved the floater to that garbage over the Lesser Antilles.

Yeah, unless they just want to be ready when 97L arrives. I'm glad to see the Leewards getting the rain they wanted...I don't think that disturbance has been too strong, just persistent.
CATLSW
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1284. Patrap
Floater 1 Imagery
Member Since: July 3, 2005 Posts: 421 Comments: 127663
NHC reacted too quickly by dropping the invest, they should have waited until tonight to see if it efficaciously reorganize itself. Albeit low level vorticity values of the Antilles wave is higher, it is elongated, and the elongation becomes pronounced at the upper levels, as it interacts with an upper level low. However the wave just east of it has a more compact and vertically stacked structure, as mentioned by the WxLogic. The fact that the environment ahead of it is moist, little shear (it is decreasing), and the northward propagation of the SER, indicates that it will move into a relatively favorable environment.
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1282. Drakoen
Cursing an admin isn't the smartest thing to do.
Member Since: October 28, 2006 Posts: 57 Comments: 29934
1281. WxLogic
Hehe... I see why nvm. :)
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Quoting Drakoen:
MIMIC-TPW confirms a 850mb vorticity maximum over the northern Lesser Antilles and a weak cyclonic rotation with ex-97L.
Hasn't the rotation been there with ex-97L all along ?
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Quoting KYhomeboy:
Understood Drak. Just saying that its hard to compare, assuming your looking for a more precise track. But looking at climatology and current conditions can warrant a guess with an aproximation.

Wunderkid...keeping it short and simple...modest convection is occurring and it has a slightly improved vorticy reading. Still not exactly healthy but with the warmer waters ahead and light sheer (I think, as I haven't looked at a map recently), it just might have a chance. Dry air looks to be diminishing from water vapor imagery...and it seems to be pullin in some moisture from the mess over/ near the antilles.

Dry air is virtually gone-
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Quoting Drakoen:
I really don't know why SSD moved the floater to that garbage over the Lesser Antilles.


I agree, that wave never stood a chance, but of course it looked so pretty earlier so everyone jumped on it lol

Former 97L still has a better chance to develop than that thing lol
About 1/4"
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1276. Drakoen
I really don't know why SSD moved the floater to that garbage over the Lesser Antilles.
Member Since: October 28, 2006 Posts: 57 Comments: 29934
I also believe canesrule is on sabbatical.
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1274. WxLogic
Wow... the blog for some reason looks a bit lighter now...
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1273. Drakoen
MIMIC-TPW confirms a 850mb vorticity maximum over the northern Lesser Antilles and a weak cyclonic rotation with ex-97L.
Member Since: October 28, 2006 Posts: 57 Comments: 29934
Understood Drak. Just saying that its hard to compare, assuming your looking for a more precise track. But looking at climatology and current conditions can warrant a guess with an aproximation.

Wunderkid...keeping it short and simple...modest convection is occurring and it has a slightly improved vorticy reading. Still not exactly healthy but with the warmer waters ahead and light sheer (I think, as I haven't looked at a map recently), it just might have a chance. Dry air looks to be diminishing from water vapor imagery...and it seems to be pullin in some moisture from the mess over/ near the antilles.
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1271. Drakoen
1264. LOL!
Member Since: October 28, 2006 Posts: 57 Comments: 29934
Quoting canesrule1:
Acemmett sent me an email right now, he got banned, lol.
...and I am sure you wont see Taz for a while either.
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1264.

Rofl..
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Good evening, Wunderfolk...
From the 8 pm NHC Discussion:
CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER NWRN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF COLOMBIA. THESE TRADE WINDS ARE FORECAST TO REMAIN FRESH TO STRONG THROUGH MONDAY AS THE SUBTROPICAL RIDGE REMAINS IN PLACE.
HOWEVER...THE PROPAGATION OF A TROPICAL WAVE JUST W OF THE LESSER ANTILLES...AND A SECOND TROPICAL WAVE THAT WILL REACH THE ERN CARIBBEAN BY TUE WILL CAUSE THE TRADE WIND PATTERN TO FLUCTUATE AS THE WAVES PASS THROUGH THE CARIBBEAN. HIGHEST WINDS ARE EXPECTED TO BE MAINLY ACROSS THE N PORTIONS OF THESE TROPICAL WAVES.
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Ex97L is starting to look impressive tonight, might yet be a player in a few days , imo.
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guys I just looked at the central atlantic sat and lookat ex-97l I see a spin of t-storms at12n 47/48w
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Dry air decreasing
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Acemmett sent me an email right now, he got banned, lol.
1263. Patrap
A good page to bookmark for Imagery thru the season.

Atlantic and Caribbean Tropical Satellite Imagery
Member Since: July 3, 2005 Posts: 421 Comments: 127663
Quoting KYhomeboy:
I dont understand how you can compare (previously 97L's) track to a past hurricane. The system hasn't even entered the Caribbean yet. The dynamics in place which steer these systems are complex and forecasting an exact or even similar path so far out makes little sense...even if there are similar atmospheric conditions etc. A storm starting near or even in the exact spot as a previous one doesnt mean it will follow a similar path.
yes but with the current steering components in the atmosphere and current movement (which is westward at over 20 mph) i believe and other people agree this will follow a similar path of dean's, its probably going to continue its current path, westward.
Quoting Drakoen:


Yea i'm monitoring it as well. It may still have a little bit left in it. A lot of systems looks like this before they enter the Caribbean and then they have the chance to get their act together. A recent example would be Felix although the invest-Felix had a better defined low level circulation.
But when he decided to get his act together he did a very good job of it.
Member Since: October 9, 2008 Posts: 0 Comments: 8279
Quoting DaaiTouLaam:
TyphoonHunter has posted his video of last night's hit on HK by Typhoon Molave.

http://www.youtube.com/watch?v=TjHKbvubZJI

A little tired this morning. It's rainy and a bit breezy and T3 as Molave's remnants keep hanging around.

Nice! And in HD too. I noticed lots of people out and even buses running, I guess they get typhoons so often.
Member Since: June 21, 2007 Posts: 10 Comments: 1657
can someone tell me in detail what is going on with ex-97l (images as well if you can)
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1257. Drakoen
Quoting KYhomeboy:
I dont understand how you can compare (previously 97L's) track to a past hurricane. The system hasn't even entered the Caribbean yet. The dynamics in place which steer these systems are complex and forecasting an exact or even similar path so far out makes little sense...even if there are similar atmospheric conditions etc. A storm starting near or even in the exact spot as a previous one doesnt mean it will follow a similar path.


I was comparing it to the invest that brought Felix I always look at climatology with the current dynamics to make a forecast. It is not irresponsible.
Member Since: October 28, 2006 Posts: 57 Comments: 29934
I dont understand how you can compare (previously 97L's) track to a past hurricane. The system hasn't even entered the Caribbean yet. The dynamics in place which steer these systems are complex and forecasting an exact or even similar path so far out makes little sense...even if there are similar atmospheric conditions etc. A storm starting near or even in the exact spot as a previous one doesnt mean it will follow a similar path.
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Quoting Drakoen:
This is what I will be looking for over the next 2-3 days in the Caribbean with a venting upper level anitcyclonic circulation north of Panamas whoose upper level ridge axis extends outward towards the Lesser Antilles.
yeah and that is giving former 97L a window for development, i think.
Quoting weatherwatcher12:

That's what I think will happen. I mentioned this sort of track earlier
yeah if this survives the Yucatan Peninsula should keep there eyes opened.
1253. Drakoen
This is what I will be looking for over the next 2-3 days in the Caribbean with a venting upper level anitcyclonic circulation north of Panamas whoose upper level ridge axis extends outward towards the Lesser Antilles. It certainly would behoove a system to get under this high's ridge axis
Member Since: October 28, 2006 Posts: 57 Comments: 29934
Quoting canesrule1:
im not talking about the intensity part i'm just talking about the route, very true though, Dean was a MONSTER!

Yeah, I figuered that :)
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looks like ex97l is tapping into the moisture from the antilles blowup
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TyphoonHunter has posted his video of last night's hit on HK by Typhoon Molave.

http://www.youtube.com/watch?v=TjHKbvubZJI

A little tired this morning. It's rainy and a bit breezy and T3 as Molave's remnants keep hanging around.
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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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