Dr. Jeff Masters' WunderBlog

Two African waves worth mentioning
Posted by: Dr. Jeff Masters, 3:51 PM GMT on July 18, 2009 +2
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
Categories: Hurricane
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1001. PcolaJess 12:44 AM GMT on July 19, 2009    
am usually just a lurker but what is DMAX?
1002. Patrap 12:45 AM GMT on July 19, 2009    
Member Since: July 3, 2005 Posts: 371 Comments: 111403
1003. Rmadillo 12:45 AM GMT on July 19, 2009    
Quoting PSLHokie:
wow, the 30-50 knots of shear really did in the Caribbean blobb!!!!


and you are surprised?
Member Since: May 27, 2009 Posts: 0 Comments: 102
1004. Patrap 12:46 AM GMT on July 19, 2009    
GOES-12 Atmospheric Imagery

These images are primarily for use in tropical storm monitoring. There are several areas to choose from providing a large-scale view of the Atlantic, down to the Gulf of Mexico. During hurricane season, the hurricanes page provides a variety of GOES atmospheric products to help monitor the active storms.
Member Since: July 3, 2005 Posts: 371 Comments: 111403
1005. LPStormspotter 12:47 AM GMT on July 19, 2009    
Quoting PcolaJess:
am usually just a lurker but what is DMAX?


Thanks was gonna ask the same question..
Member Since: July 17, 2008 Posts: 0 Comments: 378
1006. Drakoen 12:48 AM GMT on July 19, 2009    
Quoting PcolaJess:
am usually just a lurker but what is DMAX?

When the difference between the ocean temperature and the atmosphere is at it's greatest occurring before sunrise.
Member Since: October 28, 2006 Posts: 57 Comments: 29010
1007. PcolaJess 12:49 AM GMT on July 19, 2009    
oh cool thanks drak and glad to see you are back
1008. Middy83 12:50 AM GMT on July 19, 2009    
Member Since: July 21, 2008 Posts: 0 Comments: 23
1009. stormwatcherCI 12:51 AM GMT on July 19, 2009    
Quoting Drakoen:
Quoting PcolaJess:
am usually just a lurker but what is DMAX?

When the difference between the ocean temperature and the atmosphere is at it's greatest occurring before sunrise.
When do systems or invests normally get better organized ?
Member Since: October 9, 2008 Posts: 0 Comments: 8039
1010. reedzone 12:51 AM GMT on July 19, 2009    
Quoting sporteguy03:


Reedzone Invest eh?


If it continues to organize tonight, possibly re-tagged by Sunday afternoon. A low but fair chance of that happening.
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1011. Drakoen 12:55 AM GMT on July 19, 2009    
Quoting stormwatcherCI:
When do systems or invests normally get better organized ?


At diurnal maximum then system has to hold it's convection for approximately 12 hours. During this 12 hours the system has to prove itself capable of generating and/or regenerating convection.
Member Since: October 28, 2006 Posts: 57 Comments: 29010
1012. hurricane23 12:56 AM GMT on July 19, 2009    
Hey Drakoen,

All is quiet brother,the wave bringing squally weather to the northern islands is all interaction with the upper trof in the area.Just before heading out to fridays with wifey i was looking at some visible imagery of the caribbean and i was picking up the mid-level circulation racing ahead of the wave.Looks like that squally weather might make its way into southern florida come mid week.
Member Since: May 14, 2006 Posts: 8 Comments: 13276
1013. Orcasystems 12:57 AM GMT on July 19, 2009    
Member Since: October 1, 2007 Posts: 77 Comments: 26077
1014. Drakoen 12:58 AM GMT on July 19, 2009    
People keep spelling my username name wrong. Just "Drak" is fine (LOL!)

Hey Adrian,

Yea, nothing imminent out there.
Member Since: October 28, 2006 Posts: 57 Comments: 29010
1015. hurricane23 12:59 AM GMT on July 19, 2009    
Quoting Drakoen:
People keep spelling my username name wrong. Just "Drak" is fine (LOL!)

Hey Adrian,

Yea, nothing imminent out there.


My bad, just fixed it.
Member Since: May 14, 2006 Posts: 8 Comments: 13276
1017. RMM34667 1:01 AM GMT on July 19, 2009    
Called my sister in St. Thomas. She lives up on the side of a mountain. She had no idea anything was coming. But happy with the news because they are almost out of water.. During our conversation the line got really bad and then just cut off..

Thanks for GeoffreyWPB for posting that radar.
Member Since: September 7, 2006 Posts: 5 Comments: 910
1018. TampaFLUSA 1:02 AM GMT on July 19, 2009    
Quoting StormW:
Have a great evening. I'm out.

TROPICAL WEATHER "QUICKCAST" JULY 18, 2009 ISSUED 8:30 P.M. EDT

Makes sense, no hype.
Member Since: June 21, 2007 Posts: 10 Comments: 1656
1019. TexasHurricane 1:04 AM GMT on July 19, 2009    
Seems like these two waves are going to have a hard time if any developing. So what made these "worth mentioning"?

Just curious...
Member Since: July 2, 2009 Posts: 0 Comments: 2811
1020. reedzone 1:04 AM GMT on July 19, 2009    
Quoting StormW:
Have a great evening. I'm out.

TROPICAL WEATHER "QUICKCAST" JULY 18, 2009 ISSUED 8:30 P.M. EDT


Evening StormW, great analysis! Both of these features need to be watched. Convection is starting to fire up on the remnants of 97L, a banding look.
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1021. stormwatcherCI 1:05 AM GMT on July 19, 2009    
Quoting Drakoen:


At diurnal maximum then system has to hold it's convection for approximately 12 hours. During this 12 hours the system has to prove itself capable of generating and/or regenerating convection.
Thanks.
Member Since: October 9, 2008 Posts: 0 Comments: 8039
1022. TampaFLUSA 1:05 AM GMT on July 19, 2009    
Quoting reedzone:


Evening StormW, great analysis! Both of these features need to be watched. Convection is starting to fire up on the remnants of 97L, a banding look.

Dude you need to calm down no offense, but your over-hyping this storm on this blog I noticed.
Member Since: June 21, 2007 Posts: 10 Comments: 1656
1023. reedzone 1:08 AM GMT on July 19, 2009    
Quoting TampaFLUSA:

Dude you need to calm down no offense, but your over-hyping this storm on this blog I noticed.


I said on an earlier post that there is a LOW but fair chance for regeneration. I am seeing very small thin banding features on the wave, doesn't mean I'm calling it a storm just yet ;)
I also mentioned I am giving it 14 hours to regenerate, if it falls apart by Sunday morning, I won't be tracking it anymore. Conditions are better and a bit more moist. However, there is still some dry air left to contend with. So it's a wait and see deal, not over hyping.
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1024. alaina1085 1:12 AM GMT on July 19, 2009    
Thanks Storm :)
G'night.
Member Since: August 2, 2006 Posts: 0 Comments: 1234
1025. Drakoen 1:13 AM GMT on July 19, 2009    
GFS shows shear lowering in the coming days and the overall mean shear lowering as we head into August.
Member Since: October 28, 2006 Posts: 57 Comments: 29010
1027. stormwatcherCI 1:15 AM GMT on July 19, 2009    
Quoting reedzone:


I said on an earlier post that there is a LOW but fair chance for regeneration. I am seeing very small thin banding features on the wave, doesn't mean I'm calling it a storm just yet ;)
I also mentioned I am giving it 14 hours to regenerate, if it falls apart by Sunday morning, I won't be tracking it anymore. Conditions are better and a bit more moist. However, there is still some dry air left to contend with. So it's a wait and see deal, not over hyping.
You are entitled to your opinion. I don't think you need to explain yourself to anyone.
Member Since: October 9, 2008 Posts: 0 Comments: 8039
1028. BurnedAfterPosting 1:15 AM GMT on July 19, 2009    
Quoting jasoniscoolman09:


you should be banned for putting up a fake TWO map, there is no yellow circle by the CV Islands
1029. reedzone 1:16 AM GMT on July 19, 2009    
Quoting stormwatcherCI:
You are entitled to your opinion. I don't think you need to explain yourself to anyone.


I know but someone complained that I was over hyping the remnants of 97L, so I had to get that straightened out.
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1030. Becca36 1:16 AM GMT on July 19, 2009    
Hi. Ive been a lurker for over a year and have always been fascinated by the weather. I've aquired quite an education on here through reading posts and following links.Just wanted to say hi. I'll mostly lurk but if I have a question no one else asks I'll ask but please be easy on me, I am only self educated about meteorology! :) Oh, nice to finally meet you all!
Member Since: June 26, 2009 Posts: 0 Comments: 157
1031. Drakoen 1:17 AM GMT on July 19, 2009    
You can tell it has been edited lol.
Member Since: October 28, 2006 Posts: 57 Comments: 29010
1032. canesrule1 1:17 AM GMT on July 19, 2009    
Good evening everyone, can someone please inform me with the current status, was out for a while because something big happened in the building next to ours.
1033. BurnedAfterPosting 1:18 AM GMT on July 19, 2009    
Quoting Drakoen:
You can tell it has been edited lol.


yea I guess, not a very smart thing to do on this blog though
1034. reedzone 1:18 AM GMT on July 19, 2009    
Quoting Becca36:
Hi. Ive been a lurker for over a year and have always been fascinated by the weather. I've aquired quite an education on here through reading posts and following links.Just wanted to say hi. I'll mostly lurk but if I have a question no one else asks I'll ask but please be easy on me, I am only self educated about meteorology! :) Oh, nice to finally meet you all!


It's all good, we are all here to learn and help. :)
Nice to meet you to.
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1036. Becca36 1:19 AM GMT on July 19, 2009    
Thanks.:)
Member Since: June 26, 2009 Posts: 0 Comments: 157
1037. HurricaneSwirl 1:19 AM GMT on July 19, 2009    
hey the image looks pretty legit when you zoom in... lol

nice try tho
Member Since: July 7, 2008 Posts: 2 Comments: 3237
1039. stoormfury 1:20 AM GMT on July 19, 2009    
97L is trying to refire. Approaching warmer sst near 50w.
Member Since: August 22, 2006 Posts: 0 Comments: 2303
1040. reedzone 1:21 AM GMT on July 19, 2009    
Quoting Funkadelic:


I do see it has gotten a LITTLE better looking on satelite..and seems to have grown in size a bit.. But D-MAX tonight will determine if ex97L has life in her


Exactly my point
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1041. canesrule1 1:22 AM GMT on July 19, 2009    
Quoting jasoniscoolman09:
i dont see that on the website (i dont see the third one by africa)
1042. hahaguy 1:22 AM GMT on July 19, 2009    
Quoting canesrule1:
i dont see that on the website (i dont see the third one by africa)


It's a fake.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
1043. reedzone 1:22 AM GMT on July 19, 2009    
Quoting Becca36:
Thanks.:)


No problem, anytime. I will try my best to help you out, i'm not an expert, but I have been tracking storms for 10 years.
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1045. reedzone 1:23 AM GMT on July 19, 2009    
Quoting hahaguy:


It's a fake.


He should of made it code red :P
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1047. surfmom 1:24 AM GMT on July 19, 2009    
Hummmm -- bit of activity stirring.....be interesting to see this tomorrow. till then
Member Since: July 18, 2007 Posts: 30 Comments: 26538
1048. novembergale 1:25 AM GMT on July 19, 2009    
What about the bulge at the equator that developed in 1998? There are now axial tilt issues and the land under the poles began to rise which is also speeding up the ice cap melting. Why is this apparently being ignored?
Member Since: February 20, 2008 Posts: 164 Comments: 38
1049. canesrule1 1:25 AM GMT on July 19, 2009    
this is the real map...
1050. surfmom 1:26 AM GMT on July 19, 2009    
Quoting leftovers:
sometimes these systems either build themselves favorable areas or find little favorable spots where to wind themselves up.

I hear ya Left, ...guess what I'm looking for...LOL
Member Since: July 18, 2007 Posts: 30 Comments: 26538
1051. Tazmanian 1:26 AM GMT on July 19, 2009    
Quoting jasoniscoolman09:
i see three yellow circle now...



lol if you where going too make some in fake up you sould have made all of them all code reds
Member Since: May 21, 2006 Posts: 5088 Comments: 111346

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About JeffMasters
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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