New tropical depression could form off the coast of Africa

By: Dr. Jeff Masters , 1:12 PM GMT on September 25, 2009

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A tropical wave (99L) is located near 15N, 30W, about 300 miles west of the Cape Verdes Islands. This wave has seen an increase in heavy thunderstorm activity this morning, and low-level spiral bands have formed. The system can already be classified as a tropical depression using the satellite-based Dvorak technique. This morning's QuickSCAT pass showed a loose but closed circulation, with top winds of 30 mph in the heaviest thunderstorms. Wind shear is moderate, about 10 - 20 knots. There is a modest amount of dry air to 99L's west that does not appear to be interfering with the storm's organization.


Figure 1. Morning visible satellite image of Invest 99L (left side of image) and a new tropical wave moving off the coast of Africa.

As 99L moves west-northwest over the next two days, sea surface temperatures will cool by 1°C and winds shear will remain in the moderate range. Some dry air may also affect the storm. These conditions give 99L a good chance of forming into a tropical depression, and NHC has given the system a moderate (30 - 50%) chance of developing into a tropical depression by Sunday. By Monday, wind shear will increase to the high range, 20 - 30 knots, and 99L will probably weaken or be torn apart. None of the computer models forecast development of 99L or any other system in the Atlantic over the next seven days.

A new tropical wave with plenty of heavy thunderstorm activity and some spin is moving off the coast of Africa today. This wave is under a moderate amount of wind shear, 10 - 20 knots, and has some potential for development this week as it moves west or west-northwest past the Cape Verdes Islands.

The latest wind shear forecasts from our major computer models show high values of wind shear affecting most of the tropical Atlantic for the next ten days. This is typical for an El Niño year, and it will be difficult for any storms to get to hurricane strength over the next ten days because of the high shear. The latest 16-day GFS forecast predicts wind shear will decline some by the 2nd week of October, though.


Figure 2. Wind shear forecast for Thursday, October 2 at 00 UTC made by last night's 00Z run of the GFS model. Wind shear is expected to be high over most of the tropical Atlantic for the next ten days, including the Caribbean. Wind shear values below 8 m/s (about 15 knots, red colors), are typically needed to support tropical storm formation.

Jeff Masters

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719. hydrus
1:13 PM GMT on September 26, 2009
Quoting stormwatcherCI:
I know. My parents lived in the Kendall area then and I came up a year after and it was still a horrendous mess. I actually grew up in S. Fla. but have been in Cayman since 1973.
How long did you live in Florida?
Member Since: September 27, 2007 Posts: 1 Comments: 20507
718. stormwatcherCI
12:45 PM GMT on September 26, 2009
Quoting Dakster:
I can empthathize with you. I remember how long it took Dade County to get trees back after Andrew. There are still some nature conservacy areas that are nowhere near their pre-Andrew growth/look.
I know. My parents lived in the Kendall area then and I came up a year after and it was still a horrendous mess. I actually grew up in S. Fla. but have been in Cayman since 1973.
Member Since: October 9, 2008 Posts: 0 Comments: 8268
717. nrtiwlnvragn
12:44 PM GMT on September 26, 2009
New Blog
Member Since: September 23, 2005 Posts: 14 Comments: 10876
716. Dakster
12:44 PM GMT on September 26, 2009
I can empthathize with you. I remember how long it took Dade County to get trees back after Andrew. There are still some nature conservacy areas that are nowhere near their pre-Andrew growth/look.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
715. stormwatcherCI
12:41 PM GMT on September 26, 2009
Quoting Dakster:
StormwatherCI - Don't worry, be happy!

You are on a beautiful island after all.
Thanks for that. Yes, I know it is a beautiful island but wasn't so pretty after Ivan. I cried for days when I looked at it. We didn't even have trees left and I wasn't sure if it would ever come back but by the grace of God it has come very far since then although some areas still have a ways to go.
Member Since: October 9, 2008 Posts: 0 Comments: 8268
714. Dakster
12:41 PM GMT on September 26, 2009
Quoting Weather456:


??

You mean now? No

future - as along as mother nature supplies the ingredients, why not?


I meant now and/or for the remainder of this season.

Of course anything is possible in the future.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
713. Dakster
12:38 PM GMT on September 26, 2009
StormwatherCI - Don't worry, be happy!

You are on a beautiful island after all.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
712. Cavin Rawlins
12:38 PM GMT on September 26, 2009
Quoting Dakster:
Weather456 - SO bascially there is no chance of another Wilma?


??

You mean now? No

future - as along as mother nature supplies the ingredients, why not?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
711. Cavin Rawlins
12:37 PM GMT on September 26, 2009
Quoting stormwatcherCI:
Now you got me worried again. Wilma affected Cayman pretty bad too.


how? Yea I know Wilma affected the Caymans but I said the formation of Wilma was under different circumstances and orientation than what we are seeing now.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
710. stormwatcherCI
12:34 PM GMT on September 26, 2009
Quoting Weather456:


Wilma develop in the situation you are seeing now but the orientation was further north and under different circumstances. One of the key features of Wilma RI other than very warm sst and monsoonal flow was a large upper jet extending from Jamaica across the Eastern Caribbean and tied to an upper trough north of the leewards. This effectively supplied the outflow for RI.
Now you got me worried again. Wilma affected Cayman pretty bad too.
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709. Dakster
12:34 PM GMT on September 26, 2009
Weather456 - SO bascially there is no chance of another Wilma?
Member Since: March 10, 2006 Posts: 0 Comments: 10034
708. Cavin Rawlins
12:28 PM GMT on September 26, 2009
Quoting stormwatcherCI:
Ok thanks. Just like to know especially at this time of year I know the Caribbean is the hot spot.


Wilma develop in the situation you are seeing now but the orientation was further north and under different circumstances. One of the key features of Wilma RI other than very warm sst and monsoonal flow was a large upper jet extending from Jamaica across the Eastern Caribbean and tied to an upper trough north of the leewards. This effectively supplied the outflow for RI.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
707. stormwatcherCI
12:25 PM GMT on September 26, 2009
Quoting Weather456:


not likely in such a situation. The area might just be diffluent energy rather than from a surface based feature. Also with the southern push on moisture, it could eventually move into the EPAC.
Ok thanks. Just like to know especially at this time of year I know the Caribbean is the hot spot.
Member Since: October 9, 2008 Posts: 0 Comments: 8268
706. Cavin Rawlins
12:22 PM GMT on September 26, 2009
Quoting stormwatcherCI:
Thanks for clearing that up but is there any way something could form somewhere along this band of moisture ?


not likely in such a situation. The area might just be diffluent energy rather than from a surface based feature. Also with the southern push on moisture, it could eventually move into the EPAC.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
705. Dakster
12:20 PM GMT on September 26, 2009
NHC doesn't even think TD8 will be Grace as of 5am.

Looks like the winter wunderblog pattern is setting up.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
704. stormwatcherCI
12:17 PM GMT on September 26, 2009
Quoting Weather456:


I'm glad you ask. No. Nothing to worry about but look at the WV imagery of the W ATL or entire Tropical Atlantic.


Notice this flare up in the SW Caribbean is part of a band of moisture generated in the diffluent flow around the base of an upper trough digging across the area. Dry air sinking down from the SW ATL into the Caribbean and pushing this moisture south and keeping it confined to central America and the Southern Caribbean before exiting north of the Leewards. Also notice it has halt the front along the Western Gulf coast of the USA and Mexico causing it to become stationary.

Thanks for clearing that up but is there any way something could form somewhere along this band of moisture ?
Member Since: October 9, 2008 Posts: 0 Comments: 8268
703. Autistic2
12:11 PM GMT on September 26, 2009
Good morning all

What a night, Kids up half the night sick with flu or something, Wife up all night, I think I am going to be RUNNING alot today, Doctor, Pharmacy, cooking etc. At least I feel great but sleepy. Lurk off and on today.

All quiet execpt for the TD way out there?

COFFEE NOW!
Member Since: August 29, 2008 Posts: 0 Comments: 455
700. Cavin Rawlins
11:57 AM GMT on September 26, 2009
Quoting stormwatcherCI:
Good morning. Good flare-up in the sw Caribbean. Anything happening there ?


I'm glad you ask. No. Nothing to worry about but look at the WV imagery of the W ATL or entire Tropical Atlantic.


Notice this flare up in the SW Caribbean is part of a band of moisture generated in the diffluent flow around the base of an upper trough digging across the area. Dry air sinking down from the SW ATL into the Caribbean and pushing this moisture south and keeping it confined to central America and the Southern Caribbean before exiting north of the Leewards. Also notice it has halt the front along the Western Gulf coast of the USA and Mexico causing it to become stationary.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
699. Cavin Rawlins
11:49 AM GMT on September 26, 2009
Quoting leftovers:
td close to being history maybe some pieces of it will continue west


Fred part 2 - Have mercy.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
698. stormwatcherCI
11:46 AM GMT on September 26, 2009
Quoting Weather456:
Good Morning,

Tropical Depression 8
Good morning. Good flare-up in the sw Caribbean. Anything happening there ?
Member Since: October 9, 2008 Posts: 0 Comments: 8268
697. hurricanemaniac123
11:46 AM GMT on September 26, 2009
Right now I give Td 8 a 40-60% chance of becoming a Tropical Storm. I also give it a 50% chance it will stay a TD.
Member Since: September 21, 2008 Posts: 9 Comments: 688
695. IKE
11:31 AM GMT on September 26, 2009
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SAT SEP 26 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
DEPRESSION EIGHT...LOCATED ABOUT 660 MILES WEST OF THE CAPE VERDE
ISLANDS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

PUBLIC ADVISORIES ON TROPICAL DEPRESSION EIGHT ARE ISSUED UNDER WMO
HEADER WTNT33 KNHC AND UNDER AWIPS HEADER MIATCPAT3.
FORECAST/ADVISORIES ARE ISSUED UNDER WMO HEADER WTNT23 KNHC AND
UNDER AWIPS HEADER MIATCMAT3.

$$
FORECASTER BEVEN




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694. Cavin Rawlins
11:29 AM GMT on September 26, 2009
Good Morning,

Tropical Depression 8
Member Since: July 24, 2005 Posts: 407 Comments: 19076
693. pearlandaggie
11:07 AM GMT on September 26, 2009
692. feeble blog discussion just north of your post! LOL
Member Since: September 14, 2007 Posts: 3 Comments: 3963
691. TayTay
9:51 AM GMT on September 26, 2009
That storm over the Philippines is massive. I think it'll cause a lot of flooding.
690. AussieStorm
8:40 AM GMT on September 26, 2009
Floods submerge Metro Manila areas



As Typhoon Ondoy batters Luzon
By Katherine Evangelista, Edson C. Tandoc Jr.
INQUIRER.net, Philippine Daily Inquirer
First Posted 14:15:00 09/26/2009

Filed Under: Weather

MANILA, Philippines (UPDATE) Floodwaters covered Metro Manila and its outskirts as a Tropical Storm Ondoy struck the eastern side of the country on Saturday, government agencies said.

The storm, bearing winds of 85 kilometers per hour with gusts of 100 kilometers, hit the main island of Luzon near the town of Infanta at about 10 a.m. Saturday, moving west at 19 kilometers an hour, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (Pagasa) said.

About 100 families in different areas in Metro Manila have been evacuated as incessant rains caused heavy flooding in the national capital region.

Waist-deep floodwaters also prompted transport officials to close the busy South Luzon Expressway.

In Marikina City, at least 75 families (373 people) from the village of Malanday were evacuated to the Malanday Elementary School, the National Disaster Coordinating Council reported.

Twenty families or 100 people were brought to the Santolan Elementary School in the village of Santolan, Pasig City while four families (20 people) in the village of Tunasan, Muntinlupa City sought refuge in a covered court.

In San Mateo, Rizal, at least 269 families were reported to be severely affected by rising floodwater in the villages of Banaba and Sta. Ana. But the NDCC report did not say if the affected families have been evacuated.

Philippine Navy spokesperson Lieutenant Colonel Edgard Arevalo said at least 14 rescue teams had been deployed as of Saturday noon.

Radio reports said that due to heavy rain, a wall had collapsed in a suburb of Manila, leaving one child missing, but government offices could not confirm this.

Huge traffic jams clogged the roads in the capital as floodwaters caused many vehicles to stall.

Local officials made appeals on air, asking rescue agencies to send rubber boats to rescue stranded people.

Navy personnel rescued at least 40 people using two amphibious trucks in the cities of Malabon and Navotas, Arevalo said.

In Paranaque City, two rescue teams, each composed of an officer and nine enlisted personnel, were also deployed equipped with two rubber boats.

The Navy also sent eight rescue teams in Cavite and two teams in Central Luzon.

Pagasa raised storm signal warning number 2 over Aurora, Quirino, Nueva Vizcaya, Nueva Ecija, Pangasinan, Tarlac, Zambales, Pampanga, Bulacan, Rizal, Northern Quezon and Polillo Island.

Storm warning signal number 1 was hoisted over Isabela, Mountain province, Ifugao, Benguet, La Union, Ilocos Sur, Laguna, Cavite, Batangas, Mindoro Provinces, Lubang Island, Marinduque, Camarines Norte, Bataan, Metro Manila and the rest of Quezon Province.

Ondoy was expected to enhance the southwest monsoon and bring rains over Central and Southern Luzon and parts of Visayas, Pagasa said.

It advised residents living in low-lying areas and near mountain slopes in areas affected by Ondoy and the southwest monsoon to take necessary precautions against possible flashfloods and landslides.

"Those living along the coast under signals number 2 and 1 are advised to be on alert against big waves generated by the storm," Pagasa added.

Ondoy was forecast to move west northwestward at 19 kilometers per hour. By Sunday morning, it was expected to be 230 kilometers west northwest of Iba, Zambales and at 610 kilometers west northwest of Iba , Zambales by Monday morning.

An average of 20 typhoons and storms enter the Philippines from the Pacific Ocean over the eastern seaboard every year. With reports from Agence France-Press; Marlon Ramos, Philippine Daily Inquirer

Member Since: September 30, 2007 Posts: 9 Comments: 15932
689. Cavin Rawlins
7:29 AM GMT on September 26, 2009
Quoting Bordonaro:
Good Morning or Good Evening to all, depending what part of the world in which you live!!

Peace, joy and happiness to all!! It's about time for bed for myself!!

Weather 456, your blog is awesome!! Be blessed everyone!! Be back here later!!

Peace out :0)!!!!!


well thank you
Member Since: July 24, 2005 Posts: 407 Comments: 19076
688. KoritheMan
7:22 AM GMT on September 26, 2009
Quoting AussieStorm:
Sydney Dust Storm part II passed through this morning pics


Absolutely amazing.
Member Since: March 7, 2007 Posts: 553 Comments: 19915
687. Bordonaro
7:21 AM GMT on September 26, 2009
Good Morning or Good Evening to all, depending what part of the world in which you live!!

Peace, joy and happiness to all!! It's about time for bed for myself!!

Weather 456, your blog is awesome!! Be blessed everyone!! Be back here later!!

Peace out :0)!!!!!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
686. KoritheMan
7:20 AM GMT on September 26, 2009
mmkay, seems some crow is in order for me. I said earlier that TD8 was looking ragged -- and while that was technically true, it certainly looks fairly healthy at the moment. Might well become Grace.
Member Since: March 7, 2007 Posts: 553 Comments: 19915
685. JLPR
6:48 AM GMT on September 26, 2009
Member Since: September 4, 2007 Posts: 36 Comments: 5223
684. JLPR
6:48 AM GMT on September 26, 2009
Quoting Weather456:


Morning brother from another country, lol


hey neighbor XD
Member Since: September 4, 2007 Posts: 36 Comments: 5223
683. JLPR
6:46 AM GMT on September 26, 2009
Quoting GatorWX:


The dry air has evaporated??


lol don't take it literately XD
I meant it has disappeared
how Bordonaro said it would be the correct meteorological way of saying it :P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
682. Bordonaro
6:42 AM GMT on September 26, 2009
Quoting GatorWX:


The dry air has evaporated??


You mean the dry air has moistened up!!!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
681. GatorWX
6:37 AM GMT on September 26, 2009
Quoting JLPR:
actually the dry air has mostly evaporated





The dry air has evaporated??
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680. Cavin Rawlins
6:37 AM GMT on September 26, 2009
Quoting JLPR:
Morning 456


Morning brother from another country, lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
679. JLPR
6:33 AM GMT on September 26, 2009
Morning 456
Member Since: September 4, 2007 Posts: 36 Comments: 5223
678. Cavin Rawlins
6:27 AM GMT on September 26, 2009
559. hunkerdown 12:16 AM AST on September 26, 2009
Quoting pearlandaggie:
549. trust me...i've been banned for criticizing the poor grammar of those worse than my 3rd grader! lol
now thats the truth...at this point being banned means nothing here as people like that have caused this blog to become a joke for the most part. as I am sure you have noticed, most of the "regulars" are rarely here anymore.


It's becoming a sad truth though. I love this blog but have realized it's becoming worst everyday. The admins dont even seem to dont care anymore.

Good Morning everyone

Member Since: July 24, 2005 Posts: 407 Comments: 19076
677. JLPR
6:26 AM GMT on September 26, 2009
another hour later
=O


not bad
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676. AussieStorm
6:14 AM GMT on September 26, 2009
Sydney Dust Storm part II passed through this morning pics
Member Since: September 30, 2007 Posts: 9 Comments: 15932
675. JLPR
6:05 AM GMT on September 26, 2009
actually the dry air has mostly evaporated



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674. markymark1973
5:59 AM GMT on September 26, 2009
Time is running out for TD 8. It's about to hit a wall of shear. I am more interested in the wave to the SE of TD 8. It will have more moisture to work with and is a lot further south. The lower the latitude the less likely it will be sheared by the westerlies. TD 8 is picking the dust up ahead of it.
673. JLPR
5:51 AM GMT on September 26, 2009
Quoting Bordonaro:


Maybe in about 8-12 hrs she may be TS Grace!!!


yep if it continues to get more deep convection then Grace is definitely possible
Member Since: September 4, 2007 Posts: 36 Comments: 5223
672. Bordonaro
5:49 AM GMT on September 26, 2009
Quoting JLPR:


if that is 11am then this one is 12am :P


Looks like TD 8 wants to be Grace


Maybe in about 8-12 hrs she may be TS Grace!!!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
671. JLPR
5:48 AM GMT on September 26, 2009
Quoting Bordonaro:


11AM CDT PIC OF TD 8


if that is 11am then this one is 12am :P


Looks like TD 8 wants to be Grace
Member Since: September 4, 2007 Posts: 36 Comments: 5223
670. Bordonaro
5:45 AM GMT on September 26, 2009


11AM CDT PIC OF TD 8
Member Since: August 25, 2009 Posts: 20 Comments: 6785
669. kuppenskup
5:35 AM GMT on September 26, 2009
If iceman is still up I think he would be able to confirm this
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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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