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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Quoting 7544:



HEY MAN PLEASE STOP POSTING THOSE THINGS YOU ARE FREZZING UP THE BLOG ON EVERYPAGE YOU PUT THEM TY

The ignore button is your friend. ;)
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12Z UKMET
Member Since: July 19, 2008 Posts: 43 Comments: 4051
12z ECM again much further north but further southwest than then its 0z run.
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Actually even though shear is high in parts of the Atlantic and Carribean, 90L should be protected by an anticyclone which is why it strengthens so much.
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Quoting hurricane23:


What do you base that on? Just wondering.Right now there 20-30kt shear down there its not been a friendly place so far this season. Now of course that could change.


I was just basing that on TCHP but if it gets into the Central or Western Caribbean it could get shear. TUTT axis forecast down there.
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.
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Quoting poknsnok:
90l doesnt look so good.. whats everyone gonna do if this one peters out??
thank there lucky stars
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Dvorak estimates at 18Z unchanged for both 02L and 90L.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Hey did the new T# come out for both systems?
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925. P451
Quoting 7544:


hi thanks its not just me now its from post 858 ID IS P451 he did thuis on 3 other pages and everytime he post those 3 images everything frezzes SO HE OR SHE MUST LINK THEM ITS HAPPEN THREE TIMES ALL ON DIF PAGES ITS NOT FUNNY ANYMORE


Okay, enough, I've explained to you twice the situation.

If you still have problems you can:

a) put me on ignore, and my posts won't show up for you.
b) talk to the administrator of the blog

Outside of this I cannot help you. I'm not going to stop posting because 1 user believes my posts are causing him problems.

No one else has complained. Many have said outright they have no problem.

You have your options, use them, and kindly stop yelling at me.

Member Since: December 16, 2007 Posts: 7 Comments: 10202
All these super canes being enhanced from the global Al Gore warming are just killing me.
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923. 7544
Quoting P451:


I don't know if model agreement is a good thing or not. :/

We must remember that this is not yet even a depression - although it probably will be - so watching these models, going beyond 72, and especially 96 hours, it's more of a general intrigue I guess you would call it.

As Pat and others have stressed, don't necessarily focus on this storm and it's models, just be ready. It's hurricane season and if you're prone to getting one then it's time to prepare.

As to the models I'd still as usual like to see this a depression or named storm - with at least 2-3 model runs on top of that - before I really begin to trust them.

Yet, it is a little unnerving to see them all in general agreement.




HEY MAN PLEASE STOP POSTING THOSE THINGS YOU ARE FREZZING UP THE BLOG ON EVERYPAGE YOU PUT THEM TY
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Wow- aI know you are proud of him!
Good luck if, er, when it starts! ;)


Tank ya Tank ya
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Ex-TD2 needs to have a good DMAX tonight... it has been flaring up a little bit during the DMIN but not taking advantage of DMAX and if it is going to develop enough to get reclassified, then it needs to take advantage of the conditions it now has.
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Another attempt by the convection to refire. Let's see how this one plays out.

Member Since: August 19, 2006 Posts: 0 Comments: 15948
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Quoting Patrap:


Hey Patrap...looks like the x is on my house!
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www.thomasmichaelcorcoran.com

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Drak, what would provoke that type of a poleward movement on the system?
New Orleans in the house, saying hello. Lurking constantly. Just wanted to thank everyone for their input and opinions. I value them greatly.
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Quoting Drakoen:
Getting into the Caribbean is a worst case scenario. If there is evidence it may only stay in there for a short period of time then it is worth posting.


What do you base that on? Just wondering.Right now there 20-30kt shear down there its not been a friendly place so far this season. Now of course that could change.
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Quoting KEHCharleston:
Can you imagine what that would feel like, if you had been inside that room?
Talk about something that sux. (Pun intended)


Yes, I can imagine because I was in that situation when I was a kid with Hurricane Andrew. We lost much more than just one wall too.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
912. P451
Quoting saintsfan06:
P451 - all pretty close


I don't know if model agreement is a good thing or not. :/

We must remember that this is not yet even a depression - although it probably will be - so watching these models, going beyond 72, and especially 96 hours, it's more of a general intrigue I guess you would call it.

As Pat and others have stressed, don't necessarily focus on this storm and it's models, just be ready. It's hurricane season and if you're prone to getting one then it's time to prepare.

As to the models I'd still as usual like to see this a depression or named storm - with at least 2-3 model runs on top of that - before I really begin to trust them.

Yet, it is a little unnerving to see them all in general agreement.

Member Since: December 16, 2007 Posts: 7 Comments: 10202
This could seriously be a gulf storm if that ridge holds up.
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after hugo some people turned into savages on the american virgin islands. better get the national guard ready
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Quoting louisianaboy444:
How awesome! I have a lot of respect for those guys!
How is school? Or did you start the semester yet?


yeah i thought you would know him he was on the news for saying that shooting victim's life in Lafayette....and no i didn't start the semester yet i start on the 24th(hopefully) lol

Wow- aI know you are proud of him!
Good luck if, er, when it starts! ;)
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I drove through Arcadia on my way to Venice, FL to escape Hurricane Frances which was 3 weeks after Charley. Arcadia is about an hour inland, and their buildings were destroyed. Debris was piled 20 feet high by the curb.

It was eerily creepy as we were driving by it at 3 in the morning attempt to escape from a hurricane ourselves.
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907. MahFL
ex TD2 looks like a decent TD to my eyes.....
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906. 7544
Quoting 7544:


hi thanks RED ZONE its not just me now its from post 858 ID IS P451 he did thuis on 3 other pages and everytime he post those 3 images everything frezzes SO HE OR SHE MUST LINK THEM ITS HAPPEN THREE TIMES ALL ON DIF PAGES ITS NOT FUNNY ANYMORE
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Quoting Chiggy007:
12Z UKMET now pretty similar to 12Z GFDL...further South!


Moving in suite with the GFDL. Wondering if all the other models will follow.
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904. IKE
Quoting tornadofan:


Thanks Ike - will be interesting if get comes closer to GFS or continues its Fish Tales.


I think it will trend back closer to the USA.
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Getting into the Caribbean is a worst case scenario. If there is evidence it may only stay in there for a short period of time then it is worth posting.
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Well, when your windows are the original windows that were put in when the house was built in 1950, I think you'd beg to differ that the window is actually safer/better without the plywood. lol
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Quoting CaneWarning:


It can happen. I was down in Punta Gorda after Charley and saw that a few times.
Can you imagine what that would feel like, if you had been inside that room?
Talk about something that sux. (Pun intended)
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EX td2 is the one to keep an eye for now, if this trend continues by 11 tonight or 8 am , this will either be reclassified as TD or even a TS.
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Quoting IKE:


Comes out at 2 pm CDST.


Thanks Ike - will be interesting if get comes closer to GFS or continues its Fish Tales.
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898. 7544
Quoting reedzone:
Who is the culprit that is putting the virus on this blog? My computer on firefox keeps freezing on most of the times I go on here.. I want to know NOW!


hi thanks its not just me now its from post 858 ID IS P451 he did thuis on 3 other pages and everytime he post those 3 images everything frezzes SO HE OR SHE MUST LINK THEM ITS HAPPEN THREE TIMES ALL ON DIF PAGES ITS NOT FUNNY ANYMORE
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It's the crack pipe Pat no the pot.
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Quoting Chiggy007:
DRAK: So yo know that a short wave at the exact time will materialize... lol! How do you guys come up with this things and so sure about it too when models with so much Physics in them fails to show that!! :)


I just know there will be one coming.
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dry air weakens as it get close to ex-TD2 it has a big enough shield to protect it for a while ex-TD2 is tapping into 90L bands so it is getting better

Link
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894. P451
Quoting jasoniscoolman10:
wow..


More so is that this was forecasted by a number of people to occur beginning around August 15th...and they forecasted this going back to week 3 of July!

456, Storm, Dr. M, and several others I forget all foresaw this.

And, here it is.

Kudos for spotting it.
Member Since: December 16, 2007 Posts: 7 Comments: 10202
DRAK: So yo know that a short wave at the exact time will materialize... lol! How do you guys come up with this things and so sure about it too when models with so much Physics in them fails to show that!! :)
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Quoting jlp09550:

I agree. I've seen my share of photoshopped images.



I an assure you crackpots those are are
Charley Pics from Punta Gorda.

www.thomasmichaelcorcoran.com


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Looks like the thing to watch now is gonna be the ridge.
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Quoting Patrap:


Hers a FREE tip...if your prepping your Home with Plywood,Plylox clips,Armor,Kevlar,..best to Get up da road and watch it on CNN.

Above is a Home post CHarley with all those Fancy smancy steps included.


Wood, Plylox, etc. is a waste of time. It gives one a false sense of security. Anyone know what wind speeds modern double pane storm windows are rated at? 150 mph straight line dry, and 125 straightline wet. That's stronger than any peice of plywood so don't waste your time and effort boarding up. doesn't take much to puncture that balsa wood you put up. Either get metal storm shutters or nothing at all.
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Quoting reedzone:
Who is the culprit that is putting the virus on this blog? My computer on firefox keeps freezing on most of the times I go on here.. I want to know NOW!


Try with add-ons disabled.
Member Since: September 23, 2005 Posts: 14 Comments: 11303
Lafayette, la here
Hello
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i would not be too surprised to see the remains of td 2 at the end of the story to go through a period where it has higher windspeeds than 90 a larger system. if you get a small system in the florida straights its happened before you can see incredible strenghthening quickly.
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P451 - all pretty close
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Quoting hurricane23:
Watch it hit somewere near Nicaragua...


That's a little bit extreme there, Adrian. Wouldn't you think so? That'll so not happen.

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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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