Dr. Jeff Masters' WunderBlog

Disturbance 90L close to tropical depression strength; TD 2 may rise again
Posted by: Dr. Jeff Masters, 2:02 PM GMT en Agosto 14, 2009 +4
A strong tropical wave (90L), with a large circulation and a moderate amount of heavy thunderstorm activity, is a few hundred miles southwest of the Cape Verdes Islands, off the coast of Africa. This morning's QuikSCAT pass shows that 90L has a large circulation, but this circulation is not yet well-formed, as it is elongated along an east-west axis. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are gradually becoming better organized, with some spiral banding evident on the south side of the storm. Satellite intensity estimates from NOAA already put 90L at tropical depression strength with 30 mph winds, but the storm does not yet have a well enough formed circulation to be classified as a depression. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two was. However, there is some dry air from the SAL being sucked into the circulation of 90L, and this is retarding its development.

Wind shear is moderate, about 10 - 15 knots, but is forecast to fall to the low range, 5 - 10 knots, later today. Shear is then forecast to remain low for the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow 90L to develop into a tropical depression by Saturday, and potentially reach hurricane strength by Wednesday. Most of our reliable models strengthen 90L into a hurricane by Wednesday, when the storm is expected to be near the northern Lesser Antilles Islands. One important outlier is the ECMWF model, which has 90L passing to the north of the islands, and eventually recurving out to sea east of Bermuda. The ECMWF was by far the most reliable model for forecasting hurricane tracks last year. However, all of our models are pretty unreliable going out 5 days in advance for systems that have yet to reach tropical depression strength. Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.


Figure 1. The remnants of Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

Tropical Depression Two may come back
Tropical Depression Two died yesterday, but may rise again. Satellite loops of the remnants of the storm show that heavy thunderstorms are again attempting a comeback near the axis of what is now a tropical wave. However, dry air continues to interfere with the development of the thunderstorm activity, and moderately high wind shear of 15 - 20 knots is also inhibiting the process. Wind shear over the remnants of TD 2 is expected to remain in the moderate range, 10 - 20 knots, over the next four days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C two days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to the north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that any re-development of the storm will be slow to occur. NHC has given the system a medium (30 - 50% chance) of becoming a tropical depression again by Sunday morning. Only one reliable model, the NOGAPS, is predicting regeneration of TD 2. The NOAA Hurricane Hunters are flying research missions into the remnants of TD 2 today and Saturday.

I'll have an update Saturday morning, or earlier, if significant developments occur.

Jeff Masters
Categories: Hurricane
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2701. Cavin Rawlins 2:06 AM GMT en Agosto 15, 2009    
Quoting DM21Altestic:
POLL


A) 90L WILL be a TD at 11 PM.
B) 90L will be a TD tomorrow.
C) 90L will be a TD Sunday.
Z) 90L will never be a TD.


B
Member Since: Julio 24, 2005 Posts: 407 Comments: 19076
2702. canesrule1 2:06 AM GMT en Agosto 15, 2009    
Quoting DM21Altestic:
POLL


A) 90L WILL be a TD at 11 PM.
B) 90L will be a TD tomorrow.
C) 90L will be a TD Sunday.
Z) 90L will never be a TD.
A, it already was renumbered so all the other choices are useless, lol.
2703. TampaSpin 2:06 AM GMT en Agosto 15, 2009    
TD2 is moving faster than 90L and also TD2 is mow moving WSW heading toward the Caribbean as i have forecasted.
Member Since: Septiembre 2, 2007 Posts: 176 Comments: 19767
2704. Patrap 2:06 AM GMT en Agosto 15, 2009    
Member Since: Julio 3, 2005 Posts: 377 Comments: 112988
2705. mossyhead 2:06 AM GMT en Agosto 15, 2009    
Quoting DestinJeff:


destin here. Ike and 69Viking are two close by I can think of

i am in defuniak springs(mossy head)
Member Since: Julio 7, 2008 Posts: 0 Comments: 472
2706. Stormchaser2007 2:06 AM GMT en Agosto 15, 2009    
Quoting louisianaboy444:
I truely believe both will be TDs at 11


Respectfully disagree.
Member Since: Junio 9, 2007 Posts: 4 Comments: 15296
2707. canesrule1 2:07 AM GMT en Agosto 15, 2009    
Quoting Weather456:


B
its already renumbered it has to be a TD at 11.
2708. MississippiWx 2:07 AM GMT en Agosto 15, 2009    
I'm sure most people on here could do a better job at presenting the weather than the people on TWC. All that TWC is in it for now is show-boating and trying to impress their audience.

Example: Storm Master G!! Seriously, WTF???

Whatever happened to just giving the weather and how it is and leaving it at that?

Nonetheless, I never listen to TWC when it comes to tropical weather. I get much better info on this blog and just doing research myself.
Member Since: Julio 15, 2006 Posts: 14 Comments: 8911
2709. snotly 2:07 AM GMT en Agosto 15, 2009    
Quoting Weather456:


B

D?
Member Since: Agosto 27, 2005 Posts: 0 Comments: 673
2711. extreme236 2:07 AM GMT en Agosto 15, 2009    
Quoting canesrule1:
A, it already was renumbered so all the other choices are useless, lol.


02L was classified but 90L has yet to be renumbered.
Member Since: Agosto 2, 2007 Posts: 19 Comments: 19234
2712. canesrule1 2:07 AM GMT en Agosto 15, 2009    
Quoting TampaSpin:
TD2 is moving faster than 90L and also TD2 is mow moving WSW heading toward the Caribbean as i have forecasted.
but how come all the models forecast a SFLA hit?
2713. Patrap 2:07 AM GMT en Agosto 15, 2009    
Quoting rareaire:
Pat you didnt go to the game?


Nope..Pre-season Like a Blind date after the first quarter
Member Since: Julio 3, 2005 Posts: 377 Comments: 112988
2714. nishinigami 2:07 AM GMT en Agosto 15, 2009    
Quoting Patrap:
Irony always wins..

Mr. Bill PSA from 2003-4 from Creator ,He's from Louisiana.

In this public service announcement created before Katrina, Mr. Bill of SNL fame demonstrates the dangers of a hurricane hitting New Orleans.






OMG pat. That is so not funny, but I can't stop laughing....
Member Since: Agosto 24, 2008 Posts: 2 Comments: 221
2715. Cavin Rawlins 2:07 AM GMT en Agosto 15, 2009    
Quoting canesrule1:
A, it already was renumbered so all the other choices are useless, lol.



TD 2 was re-designated, 90L was never renumbered, not yet.
Member Since: Julio 24, 2005 Posts: 407 Comments: 19076
2716. 7544 2:08 AM GMT en Agosto 15, 2009    
canesrule1 2:05 AM GMT on August 15, 2009
Quoting louisianaboy444:
I truely believe both will be TDs at 11
agreed

same here
Member Since: Mayo 6, 2007 Posts: 0 Comments: 6023
2717. SavannahStorm 2:08 AM GMT en Agosto 15, 2009    
Quoting DM21Altestic:
POLL


A) 90L WILL be a TD at 11 PM.
B) 90L will be a TD tomorrow.
C) 90L will be a TD Sunday.
Z) 90L will never be a TD.


Better judgment says B, but obsessive sat. loop watching has me leaning to A.
Member Since: Septiembre 22, 2005 Posts: 18 Comments: 2140
2718. pcolasky 2:08 AM GMT en Agosto 15, 2009    
I agree Mobilegirl. And am wanting some perspectives about development? Anyone?
2719. canesrule1 2:08 AM GMT en Agosto 15, 2009    
Quoting extreme236:


02L was classified but 90L has yet to be renumbered.
yup.
2720. Ameister12 2:09 AM GMT en Agosto 15, 2009    
Quoting SavannahStorm:




Whoa, a hurricane means no school? Gnarly. I bet it brings on some like, tasty waves, too. Righteous.

Roflmao!!!
Member Since: Agosto 9, 2009 Posts: 9 Comments: 3628
2721. IKE 2:09 AM GMT en Agosto 15, 2009    
Quoting tharpgomex:
Hey Ike....lived in Defuiak during Opal....what a mess!


Yes it was. I'm up on Lake Holley. Branches...everywhere from Opal.
Member Since: Junio 9, 2005 Posts: 23 Comments: 37070
2723. Seflhurricane 2:09 AM GMT en Agosto 15, 2009    
Quoting SavannahStorm:


Better judgment says B, but obsessive sat. loop watching has me leaning to A.
thw answer is A very likely we have TD 2 and maybe TD 3 with in the hour
Member Since: Julio 14, 2009 Posts: 0 Comments: 2910
2724. futuremet 2:09 AM GMT en Agosto 15, 2009    
LOL storm master G

Member Since: Julio 19, 2008 Posts: 43 Comments: 4049
2725. duprk452 2:09 AM GMT en Agosto 15, 2009    
can someone help me figure out why the model run links that are posted dont work for me?
Member Since: Septiembre 21, 2007 Posts: 0 Comments: 137
2726. snotly 2:09 AM GMT en Agosto 15, 2009    
Quoting MississippiWx:
I'm sure most people on here could do a better job at presenting the weather than the people on TWC. All that TWC is in it for now is show-boating and trying to impress their audience.

Example: Storm Master G!! Seriously, WTF???

Whatever happened to just giving the weather and how it is and leaving it at that?

Nonetheless, I never listen to TWC when it comes to tropical weather. I get much better info on this blog and just doing research myself.


Agreed,way overdone WC!

Confucius says: Man who wants to know the weather should look out the window.
Member Since: Agosto 27, 2005 Posts: 0 Comments: 673
2727. rareaire 2:09 AM GMT en Agosto 15, 2009    
Tampa my prediction on td-2 looking better and better!!!!
Member Since: Agosto 19, 2007 Posts: 0 Comments: 1598
2728. canesrule1 2:09 AM GMT en Agosto 15, 2009    
Quoting Weather456:



TD 2 was re-designated, 90L was never renumbered, not yet.
oops, my bad, i miss read it, i think im overdue on the Heineken, if u know what i mean, lol.
2729. dcoaster 2:09 AM GMT en Agosto 15, 2009    
02L moving SW?

RAMSDIS IR Satellite
2731. cchsweatherman 2:10 AM GMT en Agosto 15, 2009    
Latest 00Z Dynamical Models


Notice the white line indicating the Official forecast. This will likely be the path the NHC uses when they start re-issuing advisories on Tropical Depression 2.
Member Since: Abril 14, 2007 Posts: 8 Comments: 4928
2732. extreme236 2:10 AM GMT en Agosto 15, 2009    
I've yet to notice the NHC officially classify a system without renumbering it first, but I can't say it couldn't happen since I don't know.
Member Since: Agosto 2, 2007 Posts: 19 Comments: 19234
2733. Seflhurricane 2:10 AM GMT en Agosto 15, 2009    
Quoting StormW:
Good evening!

2 good preparedness brochures


UNLEASHING NATURE'S FURY


AGAINST THE WIND
evening storm looks like we may have 2 TDS within the hour god help us here in South Florida
Member Since: Julio 14, 2009 Posts: 0 Comments: 2910
2734. BenBIogger 2:10 AM GMT en Agosto 15, 2009    
Member Since: Marzo 19, 2009 Posts: 0 Comments: 1419
2735. alaina1085 2:10 AM GMT en Agosto 15, 2009    
Quoting Stormchaser2007:
TD2 and 90L



This image reminds me of the movie "Twins." LOL.
Member Since: Agosto 2, 2006 Posts: 0 Comments: 1234
2736. tharpgomex 2:10 AM GMT en Agosto 15, 2009    
Hey StormW
Member Since: Julio 11, 2008 Posts: 0 Comments: 0
2737. hurricanetracker 2:10 AM GMT en Agosto 15, 2009    
TD's for sure. But more alarming NO recurvature in there track. In fact both systems appear to have, and be on sinking south of a due west motion. NOT good. Bet 'Models' will continue trending / shifting farther west. .....GOM residents stay tuned!
2738. TampaSpin 2:11 AM GMT en Agosto 15, 2009    
Quoting canesrule1:
but how come all the models forecast a SFLA hit?


Still could.
Member Since: Septiembre 2, 2007 Posts: 176 Comments: 19767
2739. STORMMASTERG 2:11 AM GMT en Agosto 15, 2009    
Hi guys.
2740. Cavin Rawlins 2:11 AM GMT en Agosto 15, 2009    
If Td 2 reaches our that could really suck. 90L was thought to be the threat but it seems TD 2 wants to follow suits.
Member Since: Julio 24, 2005 Posts: 407 Comments: 19076
2742. canesrule1 2:12 AM GMT en Agosto 15, 2009    
Quoting BenBIogger:
tight circulation, should be a TD at 11.
2743. IKE 2:12 AM GMT en Agosto 15, 2009    
Look at the outflow on TD2 now....

Member Since: Junio 9, 2005 Posts: 23 Comments: 37070
2744. Chucktown 2:12 AM GMT en Agosto 15, 2009    
Quoting MississippiWx:
I'm sure most people on here could do a better job at presenting the weather than the people on TWC. All that TWC is in it for now is show-boating and trying to impress their audience.

Example: Storm Master G!! Seriously, WTF???

Whatever happened to just giving the weather and how it is and leaving it at that?

Nonetheless, I never listen to TWC when it comes to tropical weather. I get much better info on this blog and just doing research myself.


As a TV meteorologist now for over 10 years, its not as easy as you think. Doing the weather on TV is sometimes just like being an actor. We need to keep the attention of the audience so they don't flip the channel and so I keep my job.
Member Since: Agosto 27, 2006 Posts: 0 Comments: 1411
2745. HurricaneKyle 2:12 AM GMT en Agosto 15, 2009    
Quoting Weather456:
Nothing is working this year

I found out where 95L was.....




I guess 96L was the little spot on the left.
Member Since: Agosto 10, 2009 Posts: 3 Comments: 672
2746. TampaSpin 2:12 AM GMT en Agosto 15, 2009    
We just might see at 11pm Tropical Storm ANA and TD3....that appears to me to be the case.
Member Since: Septiembre 2, 2007 Posts: 176 Comments: 19767
2747. CaicosRetiredSailor 2:12 AM GMT en Agosto 15, 2009    
Can someone give me data about the recent forward speed of exTD2?

Thanks.
CRS
Member Since: Julio 12, 2007 Posts: 0 Comments: 5256
2748. BajaALemt 2:12 AM GMT en Agosto 15, 2009    
00z NAM's starting to come out.....GFS shouldnt be too far behind
2750. canesrule1 2:12 AM GMT en Agosto 15, 2009    
Quoting TampaSpin:


Still could.
oh ok, lol

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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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