African Tropical Wave 98L Moving Over Cooler Waters

By: Dr. Jeff Masters , 2:23 PM GMT on July 23, 2013

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A strong and well-organized tropical wave that moved off the coast of Africa on Monday (98L) is located a few hundred miles south of the Cape Verde Islands and is moving west-northwest at 15 - 20 mph. Satellite images show that 98L has a decent amount of spin, but only a modest amount of heavy thunderstorms that have not changed much in intensity or areal coverage this morning. The wave is under a moderate 10 - 20 knots of wind shear, which will tend to allow slow development. A large amount of dry air lies to the north and west of 98L, and this dry air will likely interfere with development later this week. The SHIPS model predicts that wind shear will stay in the moderate range through Saturday. Ocean temperatures are barely adequate for development, about 26.5°C today, and will be below average over the region of ocean 98L will be traversing on Wednesday and Thursday, 25 - 26°C. These temperatures are very marginal for development. The Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, does not favor increased chances of Atlantic tropical cyclone formation this week. The reliable computer models for tropical cyclone genesis do not predict that 98L will develop this week. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave 98L a 40% chance of developing into a tropical cyclone by Thursday. 98L should maintain a west-northwest track through the week, and may spread heavy rains and gusty winds to the northern Lesser Antilles Islands beginning on Saturday night or on Sunday.


Figure 1. Satellite image of 98L off the coast of Africa taken at 8 am EDT Tuesday July 23, 2013, with a satellite analysis of where dry air is, as well. A large amount of dry air lies to the north and west of 98L, and will likely interfere with development later this week. Image credit: University of Wisconsin CIMSS and NOAA/HRD.

Jeff Masters

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2828. Waltanater
1:02 AM GMT on July 25, 2013
Quoting 2802. all4hurricanes:
man Dorian beat the whole 7 day intensity forecast in 6 hours
It doesn't help that the NHC always under estimates these storms either.
Member Since: May 16, 2010 Posts: 0 Comments: 1472
2827. CybrTeddy
5:55 PM GMT on July 24, 2013
Afternoon all! I see the 12z GFS came back with Dorian becoming a rather nasty Hurricane recurving towards Canada and the Northeast. Should be fun to watch.
Member Since: July 8, 2005 Posts: 259 Comments: 24015
2826. hydrus
5:23 PM GMT on July 24, 2013
Quoting 2744. weatherh98:


purely talking track. not intensity or timeline just track
Quite a few hurricanes have taken that very track, and turned out to be extremely dangerous. Not so early in the season tho.
Member Since: September 27, 2007 Posts: 1 Comments: 21173
2825. FtMyersBuc
4:04 PM GMT on July 24, 2013
Quoting 2729. LargoFl:
if that storm comes anywhere near florida the tree removal services are going to be making the big bucks huh..and imagine the rivers,lakes and streams..imagine..10-12 inches of MORE rain coming...and..we ALSO have that frontal system moving into florida just about the same time............this is not a good scenerio shaping up for soaking wet florida


Not to mention the roofing contractors.
Member Since: August 24, 2011 Posts: 0 Comments: 19
2824. Patrap
4:03 PM GMT on July 24, 2013
Ya talking to no one guys

Quoting 2813. WunderAlertBot:
JeffMasters has created a new entry.
Member Since: July 3, 2005 Posts: 423 Comments: 128216
2823. EyEtoEyE
4:02 PM GMT on July 24, 2013
Hello GT , will 99 L form , if so , will it strike the US ?
Member Since: July 6, 2013 Posts: 0 Comments: 460
2822. Ricki13th
3:58 PM GMT on July 24, 2013
Tropical Storm Dorian has tightening up conserably once it was able to leave the monsoonal flow shedding some of its disorganized convection and a decrease in shear with a more anticyclonic flow developing over it. Microwave imagery would also suggest a building eyewall on the eastern side of the compact system which leads me to think that this may peak around 60-65mph before hitting 25-26C water but that will be short lived as it will start to enter warmer waters 27C as quickly as 40W in about 24 hours. In that time span convection should wane but still be potent as it draw in moisture from the south and east.  Slight weakening could occur after that we will see how shear fares as the GFS is predicting it to stay under 20kts which will allow for it to restrengthen just north of the islands.  It remains too early to tell where it will go but recurvature or a significant northerly track is unlikely due to the 600 DM High being forecasted. The Greater Antilles, Bahamas, and SE US will have to monitor its progress closely starting this Sunday. As they maybe facing a strengthening storm bearing there way. 
Member Since: May 28, 2013 Posts: 0 Comments: 405
2821. Dakster
3:51 PM GMT on July 24, 2013
Quoting 2792. 69Viking:


Not sure where you get that assumption from. During Erin, Opal and Ivan it was giant long leaf pines and live oaks that caused a lot of the damage. It really doesn't matter whether a tree is native or not. The reason they will be at risk is because Florida is water logged meaning high winds could very easily tear up the roots of both native and non-native trees.


Point taken - but I still say the non-native stuff is MORE at risk than the native stuff that has been here for a long time and has evolved by surviving wet seasons and storms.
Member Since: March 10, 2006 Posts: 0 Comments: 10242
2820. Grothar
3:49 PM GMT on July 24, 2013
Quoting 2808. GTstormChaserCaleb:
48 hrs. the feature off the East Coast:



Here's your little 99L Caleb




Member Since: July 17, 2009 Posts: 71 Comments: 26110
2819. opal92nwf
3:49 PM GMT on July 24, 2013
Quoting 2792. 69Viking:


Not sure where you get that assumption from. During Erin, Opal and Ivan it was giant long leaf pines and live oaks that caused a lot of the damage. It really doesn't matter whether a tree is native or not. The reason they will be at risk is because Florida is water logged meaning high winds could very easily tear up the roots of both native and non-native trees.

Yeah, well I happen to have a book called StormScaping by Pamela Crawford in which the author went around Florida after the 2004 season, and cataloged how all the trees did. And Generally, the natives did better.

The Live Oaks actually did very well in the hurricanes, it's the Laurel Oaks that wreaked havoc in Central Florida northward. The Laurel Oak is easily confused with the Live Oak.

And the Longleaf pines generally do well, but yes, on wagerlogged sites they do fall over sometimes, and their top can sometimes break. And again, the easily confused Slash Pine did snap sometimes at the trunk, so that did cause some damage, maybe more than the Longleaf pine.
Member Since: May 12, 2012 Posts: 11 Comments: 2591
2818. JrWeathermanFL
3:49 PM GMT on July 24, 2013
I leave for an hour and Dorian and 99L form....
I should leave more often.

Dorian's eyelike feature might go or stay..someone said it was trying to form an eyewall. That'd be great. Hurricane Dorian could form and then weaken in 24 hours when conditions become less favorable. Just so we could just get a hurricane ;)

I really don't know about 99L....Michael might be a good analogue?? At least for track..
Member Since: July 19, 2011 Posts: 12 Comments: 2387
2817. WPBHurricane05
3:49 PM GMT on July 24, 2013
12Z GFS much stronger
Member Since: July 31, 2006 Posts: 56 Comments: 8112
2816. TheDawnAwakening
3:49 PM GMT on July 24, 2013
System near 31n and 55w should be next named storm, could impact Canada within next three to five days
Member Since: October 21, 2008 Posts: 245 Comments: 3892
2815. Patrap
3:48 PM GMT on July 24, 2013
That entity's Genesis GT is now in NE Texas actually.

Keep a eye on it.
Member Since: July 3, 2005 Posts: 423 Comments: 128216
2814. EyEtoEyE
3:48 PM GMT on July 24, 2013
I maybe late , we have a new invest 99 L ! What are chances of developement ? I also see its moving west . HMMN !
Member Since: July 6, 2013 Posts: 0 Comments: 460
2813. WunderAlertBot (Admin)
3:48 PM GMT on July 24, 2013
JeffMasters has created a new entry.
2812. Grothar
3:48 PM GMT on July 24, 2013
Quoting 2791. GTstormChaserCaleb:
TS Dorian and 99L



I told you not to lose faith in your little blob last night. I wonder how this will affect Dorian's path.


Member Since: July 17, 2009 Posts: 71 Comments: 26110
2811. JRRP
3:48 PM GMT on July 24, 2013
Quoting Patrap:
99L isnt going to the Cayman's ?

LoL

lol
Member Since: August 16, 2007 Posts: 0 Comments: 5783
2810. will40
3:47 PM GMT on July 24, 2013
Quoting 2803. Bluestorm5:


I'm a guy, lol. I hope so!


oops sorry i still think you would be a good met
Member Since: September 19, 2005 Posts: 2 Comments: 4224
2809. Patrap
3:46 PM GMT on July 24, 2013
99L isnt going to the Cayman's ?

LoL
Member Since: July 3, 2005 Posts: 423 Comments: 128216
2808. GTstormChaserCaleb
3:46 PM GMT on July 24, 2013
48 hrs. the feature off the East Coast:

Member Since: June 30, 2013 Posts: 12 Comments: 8186
2807. Patrap
3:46 PM GMT on July 24, 2013
No Natalie, they have these things called er, "Google alerts"..maybe Google dat Dawlin'
Member Since: July 3, 2005 Posts: 423 Comments: 128216
2806. wunderkidcayman
3:45 PM GMT on July 24, 2013
Any way what ever
Member Since: June 13, 2009 Posts: 2 Comments: 11925
2804. TheDawnAwakening
3:45 PM GMT on July 24, 2013
Quoting 2801. 7544:


yeap yeap moving west ?


Near zero percent chance at hitting the US, Canada is different
Member Since: October 21, 2008 Posts: 245 Comments: 3892
2803. Bluestorm5
3:44 PM GMT on July 24, 2013
Quoting 2793. will40:


good girl i think you would make a good met


I'm a guy, lol. I hope so!
Member Since: August 1, 2011 Posts: 28 Comments: 8007
2802. all4hurricanes
3:44 PM GMT on July 24, 2013
man Dorian beat the whole 7 day intensity forecast in 6 hours
Member Since: March 29, 2008 Posts: 0 Comments: 2372
2801. 7544
3:43 PM GMT on July 24, 2013
Quoting 2799. HurricaneAndre:
Brand new invest 99L.


yeap yeap moving west ?
Member Since: May 6, 2007 Posts: 0 Comments: 6810
2800. washingtonian115
3:43 PM GMT on July 24, 2013
Quoting 2793. will40:


good girl i think you would make a good met
Bluestorm is a he.lol.
Member Since: August 14, 2010 Posts: 10 Comments: 16964
2799. HurricaneAndre
3:42 PM GMT on July 24, 2013
Brand new invest 99L.
Member Since: June 11, 2013 Posts: 20 Comments: 2871
2798. VAbeachhurricanes
3:42 PM GMT on July 24, 2013
Heck of a feature off the east coast

Member Since: September 6, 2007 Posts: 0 Comments: 6481
2797. Progster
3:42 PM GMT on July 24, 2013
Quoting 2778. Neapolitan:
The swirl several hundred miles northeast of Puerto Rico and a few hundred miles due east of Bermuda:

BEGIN
NHC_ATCF
invest_al992013.invest
FSTDA
R
U
040
010
0000
201307241525
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 99, 2013, DB, O, 2013072412, 9999999999, , , , , , METWATCH, , AL992013
AL, 99, 2013072412, , BEST, 0, 304N, 556W, 20, 0, DB, 0, , 0, 0, 0, 0,


looks a little unlikely...but it is under a pretty strong 250 mb ridge and there's not a lot of shear..and a surface trough...and good SST's....hmmm
Member Since: September 4, 2007 Posts: 0 Comments: 490
2796. Ricki13th
3:41 PM GMT on July 24, 2013
The moisture  just east of Bermuda has persist long enough to acquire a low.

BEGIN
NHC_ATCF
invest_al992013.invest
FSTDA
R
U
040
010
0000
201307241525
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 99, 2013, DB, O, 2013072412, 9999999999, , , , , , METWATCH, , AL992013
AL, 99, 2013072412, , BEST, 0, 304N, 556W, 20, 0, DB, 0, , 0, 0, 0, 0,
Member Since: May 28, 2013 Posts: 0 Comments: 405
2795. opal92nwf
3:41 PM GMT on July 24, 2013
Quoting 2763. sporteguy03:
The last time we had two named systems East of the Islands in July was Dennis and Emily of 2005. Very rare but could be indicative of a busy Cape Verde season.

Exactly what I have been thinking, and yet we still have people saying this season could not amount to a whole lot.

Yeah it's amazing

2 Cape Verde Systems in July


Member Since: May 12, 2012 Posts: 11 Comments: 2591
2794. K8eCane
3:41 PM GMT on July 24, 2013
Quoting 2789. Patrap:
Nea brings the full monty.

Always.



If you mean that he don't joke about such things, I agree
Member Since: April 26, 2006 Posts: 5 Comments: 3117
2793. will40
3:40 PM GMT on July 24, 2013
Quoting 2787. Bluestorm5:
Yeah, I need to get some cash for college... been working my butt off all summer long so my family can afford to go to college.


good girl i think you would make a good met
Member Since: September 19, 2005 Posts: 2 Comments: 4224
2792. 69Viking
3:40 PM GMT on July 24, 2013
Quoting 2733. Dakster:


Only because of all the non-native trees that are here now.



Not sure where you get that assumption from. During Erin, Opal and Ivan it was giant long leaf pines and live oaks that caused a lot of the damage. It really doesn't matter whether a tree is native or not. The reason they will be at risk is because Florida is water logged meaning high winds could very easily tear up the roots of both native and non-native trees.
Member Since: August 25, 2006 Posts: 1 Comments: 3022
2791. GTstormChaserCaleb
3:40 PM GMT on July 24, 2013
TS Dorian and 99L

Member Since: June 30, 2013 Posts: 12 Comments: 8186
2790. TheDawnAwakening
3:40 PM GMT on July 24, 2013
Quoting 2786. wunderkidcayman:

lol really are you joking or is this fo real


This is in association with an upper level low over the central Atlantic heading for New Foundland, Canada
Member Since: October 21, 2008 Posts: 245 Comments: 3892
2789. Patrap
3:39 PM GMT on July 24, 2013
Nea brings the full monty.

Always.
Member Since: July 3, 2005 Posts: 423 Comments: 128216
2788. GTstormChaserCaleb
3:39 PM GMT on July 24, 2013
Quoting 2778. Neapolitan:
The swirl several hundred miles northeast of Puerto Rico and a few hundred miles due east of Bermuda:

BEGIN
NHC_ATCF
invest_al992013.invest
FSTDA
R
U
040
010
0000
201307241525
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 99, 2013, DB, O, 2013072412, 9999999999, , , , , , METWATCH, , AL992013
AL, 99, 2013072412, , BEST, 0, 304N, 556W, 20, 0, DB, 0, , 0, 0, 0, 0,
That would be my blob! :D
Member Since: June 30, 2013 Posts: 12 Comments: 8186
2787. Bluestorm5
3:38 PM GMT on July 24, 2013
Quoting 2780. will40:


well consider it lucky. lots of people would like to have an 8 hr shift
Yeah, I need to get some cash for college... been working my butt off all summer long so my family can afford to go to college.
Member Since: August 1, 2011 Posts: 28 Comments: 8007
2786. wunderkidcayman
3:38 PM GMT on July 24, 2013
Quoting 2778. Neapolitan:
BEGIN
NHC_ATCF
invest_al992013.invest
FSTDA
R
U
040
010
0000
201307241525
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 99, 2013, DB, O, 2013072412, 9999999999, , , , , , METWATCH, , AL992013
AL, 99, 2013072412, , BEST, 0, 304N, 556W, 20, 0, DB, 0, , 0, 0, 0, 0,

lol really are you joking or is this fo real
Member Since: June 13, 2009 Posts: 2 Comments: 11925
2785. Hurricanes305
3:38 PM GMT on July 24, 2013
Quoting 2778. Neapolitan:
BEGIN
NHC_ATCF
invest_al992013.invest
FSTDA
R
U
040
010
0000
201307241525
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 99, 2013, DB, O, 2013072412, 9999999999, , , , , , METWATCH, , AL992013
AL, 99, 2013072412, , BEST, 0, 304N, 556W, 20, 0, DB, 0, , 0, 0, 0, 0,


Oh oh the switch has been flipped on.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
2784. GTstormChaserCaleb
3:38 PM GMT on July 24, 2013
18 hrs.

Member Since: June 30, 2013 Posts: 12 Comments: 8186
2783. Bluestorm5
3:37 PM GMT on July 24, 2013
Quoting 2773. DavidHOUTX:
Might be dry air. However, I need to see microwave first...
Member Since: August 1, 2011 Posts: 28 Comments: 8007
2782. JRRP
3:37 PM GMT on July 24, 2013

Member Since: August 16, 2007 Posts: 0 Comments: 5783
2781. TheDawnAwakening
3:37 PM GMT on July 24, 2013
Major convective explosion off of NC and SC in association with mid level low over GA
Member Since: October 21, 2008 Posts: 245 Comments: 3892
2780. will40
3:37 PM GMT on July 24, 2013
Quoting 2768. Bluestorm5:
Just a wrong day to have 8 hours shift at work... oh well. I should have another blog up either tonight after 11 pm or the first thing tomorrow around 12 or 1 pm.


well consider it lucky. lots of people would like to have an 8 hr shift
Member Since: September 19, 2005 Posts: 2 Comments: 4224
2779. Progster
3:36 PM GMT on July 24, 2013
Quoting 2753. GTstormChaserCaleb:
ncstorm has been saying that for days and I have been watching the models too show this area.


This blog is so often totally on top of things :)
Member Since: September 4, 2007 Posts: 0 Comments: 490
2778. Neapolitan
3:35 PM GMT on July 24, 2013
The swirl several hundred miles northeast of Puerto Rico and a few hundred miles due east of Bermuda:

BEGIN
NHC_ATCF
invest_al992013.invest
FSTDA
R
U
040
010
0000
201307241525
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 99, 2013, DB, O, 2013072412, 9999999999, , , , , , METWATCH, , AL992013
AL, 99, 2013072412, , BEST, 0, 304N, 556W, 20, 0, DB, 0, , 0, 0, 0, 0,
Member Since: November 8, 2009 Posts: 4 Comments: 13524

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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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