Disturbance 90L close to tropical depression strength; TD 2 may rise again

By: Dr. Jeff Masters , 2:02 PM GMT on August 14, 2009

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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

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And now Beachie, the gals are back! Where is Surfmom?
Member Since: Posts: Comments:
My "illegal" site still says TD...
Member Since: August 2, 2007 Posts: 19 Comments: 19234
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Quoting sammywammybamy:
My Index finger is Hurting...

Switching to Middle...

Then Thumb
stay on target, stay on target!!!
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Quoting IKE:



well...

at least that looks a bit more hopeful for us in the TCI
Member Since: July 12, 2007 Posts: 0 Comments: 5996
Quoting sammywammybamy:
My Index finger is Hurting...

Switching to Middle...

Then Thumb


Don't you dare give us that middle finger son.
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3077. Patrap



.."Go Ahead Blogger,your on the AIR..!

..do you have the 11pm for Us here in Wunderland" ..?
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Quoting mobilegirl81:

Did Frederic reck them in '79?
No, but Katrina did. Then the economy did. Not building as much as they once did. When I worked there in '90 there we over 15,000 employees. Now only about 7K. I left there 3 years ago after a pipe fell on my neck and broke it.
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Quoting CycloneOz:


...and a believe that came again in 2004 when Hurricane Ivan struck.

pensacola would be the oldest settlement instead of st. augustine if a hurricane didn't wipe them out.
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Quoting JRRP:


lol lol lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting extreme236:


Try ALT+F4, it works better.


NOOO!! Don't do that! LOL
Member Since: July 31, 2006 Posts: 56 Comments: 8112
now we have a race
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Quoting sammywammybamy:
My Index finger is Hurting...

Switching to Middle...

Then Thumb


Dont use your head when you run out of fingers.


Dont want you ending up like a politician.
Member Since: June 9, 2007 Posts: 4 Comments: 15776
3070. IKE
All quiet on NHC site for Atlantic.

Dart tourney going on outback.....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
So good to see many of the old timers here, hi Tigger, great to see you.

All of this is too funny.
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3020.

Pat - great pic! I am about to bust a gut laughing....... great entertainment here!
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Quoting sammywammybamy:
May i have a Giant thumb Please?

to press the F5 Key


Try ALT+F4, it works better.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
4 minutes to launch and they cant find the astronauts, lol lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting IKE:


Whoa, pretty good Southward shift there, Ike.
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starting to think we may have TD2 at 5Am still not out 5 Minutes to 11pm
Member Since: July 14, 2009 Posts: 0 Comments: 2990
3063. JRRP
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Quoting extreme236:
Advisory isn't out yet cause their still at my house arresting me for using their "illegal" website.


ROFLMAO!!!!
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GO SAINTS!!! I see you didn't make it to
the game huh Pat?
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Quoting Weather456:


sometimes the blog kicks in and out due to high traffic.


Correct me if I'm wrong but NOAA didn't update there predicition until well after 5:00 pm est...are they runnung late again ?
3059. centex
You might also try CTL F5 for variety
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Quoting extreme236:
Advisory isn't out yet cause their still at my house arresting me for using their "illegal" website.


LMAO!
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Quoting extreme236:
Advisory isn't out yet cause their still at my house arresting me for using their "illegal" website.
ROFLMAO!!!!!!!!!!!!!!!HAHAHAHA!!!!!!!!LMAO!!!!!!!LOL
The Torches and pitchfork stand opens in 5 minutes!
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3054. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
I think they are classifying 90L
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Quoting extreme236:
Advisory isn't out yet cause their still at my house arresting me for using their "illegal" website.


the arrest has been going on for 30 minutes now. lol lol are they interrogating you.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting extreme236:
Advisory isn't out yet cause their still at my house arresting me for using their "illegal" website.


OH NO........ROFLMAO
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bouncin in for a few...omg...this place is hoppin tonight...read about the shipyard in pennsicola if a cane hit...SC is long overdue for a cane too...and we have deyton here plus the port...talk about causin chaos and damage...
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((( Baha!! .. with an H ))) Just in time (maybe) for the TWO! Good to see you!
Member Since: September 25, 2007 Posts: 53 Comments: 8533
Quoting Stormchaser2007:


God forbid we have fun.

Who knows what could happen.

We might get off topic.

this fun is better then all the fighting i have seen on here.
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Quoting Patrap:
..Come In CycloneOz,..you got a copy on me,..JFV,..you there ?..

Test,Test...



Same idea, more streamlined...but just as geeky! :)

Good find...you'll see that look next week on the live hurricane webcam. :D
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Coming up to 11pm...still:

Atlantic - Caribbean Sea - Gulf of Mexico

There are no tropical cyclones at this time.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
3044. jipmg
Quoting extreme236:
Advisory isn't out yet cause their still at my house arresting me for using their "illegal" website.


ROFLMAO
I say we sacrifice Sammy to the NHC!

They may make the advisory faster!
Member Since: June 9, 2007 Posts: 4 Comments: 15776
Quoting GatorWX:
Who cares what the nhc says at 11??? If they don't declare it until tomorrow, does it matter? It's obviously going to develop. We all know where to find the advisories, so if you want to see them, take a gander at 11. I can't stand when people post huge advisories and usually more than one person posts them. Post links PLEASE!!

GO REBELS!!
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i don't even have the NHC site open, lol
3039. jipmg
lol im not pressing F5, I expect the advisory to be late..
Advisory isn't out yet cause their still at my house arresting me for using their "illegal" website.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
LOL !!!!
Member Since: September 25, 2007 Posts: 53 Comments: 8533
Quoting Tazmanian:



your going to in up get ban if you keep this up


Taz take a chill......go to bed!
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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.