New tropical wave has potential to develop

By: Dr. Jeff Masters , 2:17 PM GMT on July 28, 2006

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A new area of concern has developed near 8N 38W, about 1500 miles east of the southernmost Lesser Antilles Islands. Residents of the islands will want to keep a close watch on this tropical wave over the next few days, as it has the potential to develop into a tropical storm. The tropical wave has a concentrated area of heavy thunderstorms, some upper level outflow, and the beginnings of a surface circulation. The latest pass of the QuikSCAT satellite at 4:44am EDT today showed a strong wind shift associated with the wave, but not a closed circulation at the surface. Winds in the strongest thunderstorms were about 30-35 mph, with one heavy squall ahead of the wave creating winds of up to 50 knots (57 mph).


Figure 1. QuikSCAT winds from 4:44am EDT Fri Jul 28. The winds are plotted using the standard station model. The black wind barbs mark where it is raining. Only the colored wind barbs are reliable. Black ones are unreliable, as rain contaminates the measurement of wind by the QuikSCAT satellite.

The wave is under about 15 knots of wind shear, and this shear is forecast to gradually weaken over the next two days, which may allow the wave to organize into a tropical depression. This organization will be slowed by the wave's close proximity to the Equator. Disturbances south of about 10 degrees north latitude frequently have trouble organizing, since they can't leverage the Earth's spin much to help them develop their own circulation. The forecast track of the system (Figure 2) takes it west at about 20 mph through Sunday, then curves it more to the west-northwest. Some very dry air laden with African dust lies to the north, so this may act to inhibit development. Once the wave nears the islands, some significant wind shear may affect it, but it is too early to be confident of this forecast.


Figure 2. Preliminary model tracks for the tropical wave approaching the Lesser Antilles Islands.

Tropical wave over the Bahamas and central Caribbean
A tropical wave over the southeastern Bahama Islands extends south through the central Caribbean to Columbia. This wave is moving west-northwest at 20-25 mph, and is not expected to develop today or Saturday due to wind shear of 20 knots. The wave should reach the Gulf of Mexico on Sunday, where wind shear will be marginal for development.

Jeff Masters

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1436. caneman
9:48 PM GMT on July 29, 2006
I wish death and destruction on this tropical blob. It has irritated Caneman for days now and nigh is the time for this blob to meet a slow, dry air ladden death.
Therefore, Caneman will set in motion the events that will dispense with this rather unsightly looking mass of clouds.
Caneman will update his blog later on.
Member Since: May 27, 2003 Posts: 14 Comments: 100
1435. MZT
2:16 PM GMT on July 29, 2006
new blog up
Member Since: September 24, 2005 Posts: 0 Comments: 793
1434. IKE
2:11 PM GMT on July 29, 2006
he has an update...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1432. IKE
2:09 PM GMT on July 29, 2006
Actually the slight circulation I think I see is South/SouthEAST of the Dominican Republic...not south of...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1430. Cavin Rawlins
2:06 PM GMT on July 29, 2006
Posted By: rxse7en at 10:03 AM AST on July 29, 2006.
456,

According to that chart, it looks like PR Blob will face some 30+kt shear soon, eh?


Yes it will face wind shear soon, but until then, its located in favourable upper level winds....
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1429. IKE
2:04 PM GMT on July 29, 2006
yup...and 99L has smooth sailing if it can add convection...
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1428. Cavin Rawlins
2:04 PM GMT on July 29, 2006
Taz, 99L isnt going bye-bye yet....it did the only thing possible that would help it develop, slowed down and moving slightly north of due west. It still has limited convection.

But I drop my chances to 25% that it become TD 03 or 04.

...SPECIAL FEATURE...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 42W/43W SOUTH OF 18N
MOVING WEST 20 KT. A 1012 MB LOW PRESSURE CENTER IS ALONG THE
WAVE FROM 8N TO 9N. ISOLATED MODERATE SHOWERS AND POSSIBLE
THUNDERSTORMS EXIST FROM 6N TO 12N BETWEEN 40W AND 47W.
THE LOW CENTER CONTINUES TO SHOW SIGNS OF BECOMING BETTER
ORGANIZED. UPPER LEVEL WINDS ARE EXPECTED TO BECOME GRADUALLY
MORE CONDUCIVE FOR FURTHER DEVELOPMENT...AND A TROPICAL
DEPRESSION MAY FORM DURING THE NEXT DAY OR SO AS THE SYSTEM
MOVES WESTWARD ABOUT 17 KT.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1427. rxse7en
2:03 PM GMT on July 29, 2006
456,

According to that chart, it looks like PR Blob will face some 30+kt shear soon, eh?
Member Since: August 21, 2005 Posts: 0 Comments: 529
1426. Cavin Rawlins
1:59 PM GMT on July 29, 2006
1200UTC wind shear shows that both the wave and 99L are in favourable upper level winds...
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1425. IKE
1:59 PM GMT on July 29, 2006
He should be updating soon....
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1424. aquak9
1:58 PM GMT on July 29, 2006
...pushing nearly 1500 posts...hoo boy just wait till we really get a mess on our hands
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1423. IKE
1:58 PM GMT on July 29, 2006
Looking at a WV loop...almost seems a slight circulation south of DR...
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1422. Tazmanian
1:57 PM GMT on July 29, 2006
99L is going bye bye oh dr M may be off this weekend
Member Since: May 21, 2006 Posts: 5091 Comments: 115125
1421. Cavin Rawlins
1:57 PM GMT on July 29, 2006
Posted By: MichaelSTL at 9:55 AM AST on July 29, 2006.
I don't think floater 2 was actually moved over to where the PR wave is; it was probably already there from an earlier invest.


from 96L
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1420. sarepa
1:55 PM GMT on July 29, 2006
here at the dominican republic is starting to get rainy
Member Since: January 17, 2006 Posts: 0 Comments: 26
1418. Andrew92
1:52 PM GMT on July 29, 2006
Yes it is.
1417. IKE
1:51 PM GMT on July 29, 2006
They need to move floater 2 slightly to the west...the PR blowup/blob/wave is outrunning it.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1416. seflagamma
1:47 PM GMT on July 29, 2006
So we are looking more at the PR blob rather than the one in the Atlantic? Hope Dr Master's comes on soon with an updated blog for us!

{{{skye}}} have a wonderful SAturday!
Member Since: August 29, 2005 Posts: 298 Comments: 40903
1415. Cavin Rawlins
1:46 PM GMT on July 29, 2006
9:15am EDT - 99L looks sick.....Just got to wait out this one....well until 99L earns some attention, i am focusing on the Puerto Rican wave for now....
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1413. IKE
1:46 PM GMT on July 29, 2006
accuweather has a real impressive morning update..."Still no development in the Atlantic Basin, but a few stronger waves continue to move through the region."....

Geez...probably a lot of thought went into that...
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1412. Cavin Rawlins
1:44 PM GMT on July 29, 2006
no problem rays
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1411. aquak9
1:37 PM GMT on July 29, 2006
hi rays...i'll chat at ya in your blog...

rx7vn...I took care of the chinch bugs early this year. I paved my entire yard w/cement, and painted it green.
Member Since: August 13, 2005 Posts: 166 Comments: 25937
1410. Skyepony (Mod)
1:37 PM GMT on July 29, 2006
Sorry Gamma, I'm brain dead before 10am.lol Interesting article, did they post an online version? I'll have to check back later, off to enjoy Saturday things.
Member Since: August 10, 2005 Posts: 163 Comments: 37852
1409. Raysfan70
1:35 PM GMT on July 29, 2006
thanks 456.

I just don't trust that one.
Member Since: July 28, 2005 Posts: 138 Comments: 57354
1408. Raysfan70
1:34 PM GMT on July 29, 2006
thanks 456.
Member Since: July 28, 2005 Posts: 138 Comments: 57354
1407. Raysfan70
1:33 PM GMT on July 29, 2006
What are the chances that you all are giving for the PR Blob?
Member Since: July 28, 2005 Posts: 138 Comments: 57354
1406. Cavin Rawlins
1:32 PM GMT on July 29, 2006
Here is a close up look...Shear, dust and SST are favorable. But awaiting the 1200UTC wind shear map to see if wind shear will remain low....10% chance of development until then.....
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1404. Cavin Rawlins
1:29 PM GMT on July 29, 2006
Puerto Rican Wave is increasingly looking better than 99L...
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1403. IKE
1:29 PM GMT on July 29, 2006
The PR blob is firing off some impressive thunderstorms...suppose to move west @20-25mph according to this mornings PR discussion...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1401. Cavin Rawlins
1:25 PM GMT on July 29, 2006
8:45am EDT-Good structure, limited convection....30% chance.....



Member Since: July 24, 2005 Posts: 407 Comments: 19076
1400. rxse7en
1:25 PM GMT on July 29, 2006
Hiya K9! We really could use some rain here, eh? Can't believe how many lawns have been infested by THE CHINCH!!! this summer.

Beware THE CHINCH!!!
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1399. aquak9
1:22 PM GMT on July 29, 2006
g'morning rxs7n neighbor...as usual, all calm, hot, and dry here...

Thanks folks!
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1398. rxse7en
1:22 PM GMT on July 29, 2006
456,

On that link I posted for shear, if you click -3hours and +3hours you can see the field for 40kt shear is increasing in the area above PR. Don't know if it'll expand enough to influence the blob though.


B
Member Since: August 21, 2005 Posts: 0 Comments: 529
1397. Cavin Rawlins
1:21 PM GMT on July 29, 2006
Look at that blob in the middle of the north atlantic.....

Member Since: July 24, 2005 Posts: 407 Comments: 19076
1395. chessrascal
1:20 PM GMT on July 29, 2006
when is the next update????
1394. rxse7en
1:20 PM GMT on July 29, 2006
456,

You are correct. I was looking above PR. Right where the blob is, and is going--if it ever moves--the shear is favorable!

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8shr.html
Member Since: August 21, 2005 Posts: 0 Comments: 529
1393. SLU
1:19 PM GMT on July 29, 2006
yes St. Lucia
Member Since: July 13, 2006 Posts: 13 Comments: 5163
1391. aquak9
1:18 PM GMT on July 29, 2006
hey RD...can ya give me a very quick run down of what's shaping up(or falling apart) out there? Thanks.
Member Since: August 13, 2005 Posts: 166 Comments: 25937
1390. aquak9
1:16 PM GMT on July 29, 2006
G'morning folks! Good to see ya'll keeping an eye on everything for us!
Rain-drool? you been up all nite? :)
Member Since: August 13, 2005 Posts: 166 Comments: 25937
1389. seflagamma
1:16 PM GMT on July 29, 2006
sorry, forgot this is the blog where you just get ignored unless the right bloggers are on here...

will be back later when the others arrive for information.
Member Since: August 29, 2005 Posts: 298 Comments: 40903
1387. Skyepony (Mod)
1:15 PM GMT on July 29, 2006
Check it out ~ the NHC answer my question I had yesterday as far as if the stormage over South America was associated with the wave over the Bahamas, in the 8am discussion...

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 81W SOUTH OF
22N MOVING WEST 20 KT. THE NORTHERN PART OF THE WAVE IS PASSING
THROUGH THE AREA OF BAHAMAS-TO-STRAITS OF FLORIDA-TO-NORTHWESTERN
CARIBBEAN SEA MIDDLE TO UPPER LEVEL LOW CENTER AND TROUGH.
THE FLOW ACROSS THE WAVE ELSEWHERE IN THE WESTERN CARIBBEAN SEA
IS ANTICYCLONIC AT THE UPPER LEVELS. STRONG SHOWERS AND
THUNDERSTORMS ARE SOUTH OF 9N IN THE GULF OF URABA OF COLOMBIA...
PROBABLY MORE RELATED TO THE ITCZ THAN TO THIS WAVE.

Thanks MT:)

Guess that discounts my reasoning on why this one won't develop, though it's not looking real menising.
Member Since: August 10, 2005 Posts: 163 Comments: 37852
1386. Cavin Rawlins
1:13 PM GMT on July 29, 2006
There is not 40knots of shear over the wave south of PR......It is in 0-20knots of shear.
Member Since: July 24, 2005 Posts: 407 Comments: 19076

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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.