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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Ana is center is exposed again. lol
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Quoting IpswichWeatherCenter:


Hahah, if TD3 skips TD status then we will need soccer crow.
Crow


rofl hey man... can someone explain to me the crow deal... lololol i dont get it! haha
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good morning guys let me guess we have TS ana and TD3 give me everything you got on TS ANA
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Quoting hurricane556:
surface low forming southeast of the florida keys


key west radar,.. you are 100% correct, this will form and hit the upper gulf. hopefully nothing too big
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Miami time to check your supplies. If it were me I would buy gas, food and water now. Beat the rush. I always figure you will burn the gas, eat the food and drink the water if it does not come.
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Quoting A4Guy:
4598.
Is that a crow? Looks like a Grackle


Hahah, if TD3 skips TD status then we will need soccer crow.
Crow
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Quoting IpswichWeatherCenter:


I note how all those 0/0/0 noobs have run away.


I'm not a noob...but I sure loved the 0,0,0 condition while we had it! :)

Still...1,0,0 ain't that bad considering, huh? :)
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I am just glad we have official advisories out know and the model speculation can wane.
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4625. IKE
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Quoting A4Guy:
4598.
Is that a crow? Looks like a Grackle


http://www.nps.gov/prsf/naturescience/american-crow.htm
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wow GOM wacth out!!
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Quoting TheCaneWhisperer:


Talk about around the block and back, sheesh, lol. This is going to be a tough situation with another a day or so behind, most likely Bill will follow Ana. With the size difference I don't see Ana altering Bills path too much. Granted Ana will expand with latitude but not that much.

I could see Ana making a path for 90L and laying it with moisture
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What happened to El Nino suppressing storm development? LOL!

It's going to be a mad house later at the grocery store and HD. My news posted a story on facebook about getting your hurricane plan ready.

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Quoting FSUstormnut:
wx underground also shows a 35mph invest? i thiink we have td3 not bill just yet!
Note the coordinates on that. It is 90L
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I don't think they'll skip TD yet I think they'll go to TD 3 to be safe and wait & watch and then if things stay good go to TS Bill later this evening tonight at the latest.
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I bet Stormchaser is happy he doesn't have to do that sex change operation on Bill.

My best guess is TD 3 at 11am and TS Bill by 5pm or 11pm or a special advisory today.
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surface low forming southeast of the florida keys
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Quoting CrazyDuke:


I was referring to the GFS that shows Ana bombing out and 90L trailing close behind making a b-line for what looks like S. Florida.
I agree with it. There is no way ana stays a ts if it is over those warm waters for so long. I could definitely see this becoming a big cane
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We may have a 2nd Tropical Depression in the Central Pacific. Well at least the NRL says so.
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am looking forword too what the nhc has too say on TD 3
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Good morning

From looking at visible sat loops I can see the center of Ana moving out from under weakening convection indicating SW shear. The ULL to the N of Ana has been plaguing the system from yesterday and combined with the very dry environment it looks like Ana may struggle to hold on to TS status.

This one is fighter though as we have seen.
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You know this yellow crayon around on the sat image has me thinking "Humberto."

Why does the NHC have to be sooooo conservative? That sucker is spinning up.

Humberto - 8 hours... how long does this one need to cook before NHC upgrades?

The NHC is doing it again!

NOTHING!
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4610. KBH
I only have the hypothesis now, I am pretty sure that all the data collected from stormfury can determine which tropical waves off the african coast are likely to develop, which should reduce the area
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4609. 7544
Quoting Cotillion:
It's still two hours from the advisory.

We might see a special one.


in two hours it might be a ts instaed
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Quoting P451:


So after all this time, pre-Ana became Ana and
the "Bill Wave" is about to become Bill.

Vindication for those who "knew it all along?"

heh....



Talk about around the block and back, sheesh, lol. This is going to be a tough situation with another a day or so behind, most likely Bill will follow Ana. With the size difference I don't see Ana altering Bills path too much. Granted Ana will expand with latitude but not that much.
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It's still two hours from the advisory.

We might see a special one.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting Tazmanian:
Atlantic
green ball03L.THREE
green ball02L.ANA


I didn't know Ana was also called "greenball" Lol.

I note how all those 0/0/0 noobs have run away.
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4605. A4Guy
4598.
Is that a crow? Looks like a Grackle
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Quoting TightLines305:


Just woke up to your post… unbelievable. love living in Miami.
double barrel shotgun!
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wx underground also shows a 35mph invest? i thiink we have td3 not bill just yet!
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03L.THREE, TRACK_VIS, 15 AUG 2009 1200Z UTC (Z)
Member Since: June 29, 2007 Posts: 0 Comments: 1136
4601. IKE
...
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Quoting presslord:


C'mon Thel!!! What's wrong with you?! You know JFVWS doesn't want to hear thast...
Quoting thelmores:
Would like to point out it is somewhat rare for a land falling cane on east of Florida..... doesn't mean it won't happen, but I think the models could shift a little from their final resolution...... shift left or right?

I would prefer to see a shift right and going out to sea, a shift left could take Ana into the GOM and i don't want to see that happen with the high SST's and TCHP in the GOM atm.
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2291. stormno 11:01 PM EDT on August 12, 2009
if you guys continue to follow the computers you all are going to drive yourselves crazy...you cant make your own forecast without those computers...what a shame.the computers have yet to be right all season long...guys get a life do your own homework you will feel better..computers will get you no where..i have information rolling into my office everyday its sure not from computers...i told you 3 days ago i was watching the GOM for potential development over the weekend..i didnt need computers for that lol...in fact computers havent even picked up what im seeing down there..guys like i told you earlier its to hostile in the caribbean and atlantic for something to form...anna will form in the GOM
...Stormno

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Atlantic
green ball03L.THREE
green ball02L.ANA
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2009 Storms
All Active Year

Atlantic
03L.THREE
02L.ANA
01L.ONE




Member Since: June 29, 2007 Posts: 0 Comments: 1136
Quoting AussieStorm:

That has Ana dissipating. Isn't Fla ment to get Ana as a TS?


I was referring to the GFS that shows Ana bombing out and 90L trailing close behind making a b-line for what looks like S. Florida.
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Quoting Tazmanian:



no there was not


dr m blog was vary new back at that time


He might mean views.

Doc. Master's blog rarely goes about 3100 posts.
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it does aussie, click on all up there by 2009
Member Since: June 29, 2007 Posts: 0 Comments: 1136
4592. snotly
Quoting KBH:

Thanks Snotly, very informative. I coul see why Storm fury was deema failure, not suffient analysis before and after implementation. I mean waiting a day before the storm/ hurricane is due to hit land is rediculous. I have a hypothesis ... would a few tonnes of saharan african dust at the source of origin do any good?



how do we predict the source of origin? plus we are talking about a massive scale here square kilometers not square feet.
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NRL has taken down 90L they just designated 03L. I believe we may have TD 3 at the least.
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or does he? press...
Member Since: June 29, 2007 Posts: 0 Comments: 1136
Quoting AussieStorm:

I'm looking at the navy site now and it doesn't say 03L


Click on all storms.

It's in the process of changing it.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting thelmores:
If it walks.... and quacks.... and looks..... like a TD...... must be one! LOL




TD 3 looks more like a strong TS
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Urgent care is open on Saturdays in case anyone hurts their F5 finger...
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Quoting DaytonaBeachWatcher:
navy site says 03L THREE

I'm looking at the navy site now and it doesn't say 03L
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Quoting thelmores:
Would like to point out it is somewhat rare for a land falling cane on east of Florida..... doesn't mean it won't happen, but I think the models could shift a little from their final resolution...... shift left or right?


C'mon Thel!!! What's wrong with you?! You know JFVWS doesn't want to hear that...
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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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