Little change to TD 7; 93L may develop off the coast of Africa

By: Dr. Jeff Masters , 1:57 PM GMT on August 10, 2012

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Tropical Depression Seven continues westward across the central tropical Atlantic with little change in appearance. Looking remarkably like the tropical depression that became Tropical Storm Ernesto last week, TD 7 has a limited region of heavy thunderstorms, as seen on satellite loops. A large amount of dry air to the west and north is visible on water vapor satellite loops, and this dry air is interfering with TD 7's heavy thunderstorms. Wind shear is a light 5 - 10 knots, which is favorable for intensification. Ocean temperatures are 26.5°C, which is a bit on the cool side, but these temperatures are 0.5° warmer than on Thursday. Winds at the Middle Atlantic buoy 41041 peaked at 29 mph, gusting to 38 mph, at 1:50 am EDT this Friday morning, when the center of TD 7 passed about 40 miles to the south. TD 7 will pass about 60 miles south of buoy 41040 near midnight tonight. The first hurricane hunter mission into TD 7 is scheduled for Saturday morning.


Figure 1. Morning satellite image of TD 7.

Forecast for TD 7
TD 7 formed about 400 miles east-northeast of where Ernesto became a tropical depression, as seen on our wundermap. Atmospheric and oceanic conditions are currently quite similar to what Ernesto experienced, and I expect TD 7 will struggle with dry air like Ernesto did. The SHIPS model predicts that shear will remain light through tonight, then rise to the moderate range on Saturday, when the storm will encounter upper-level southwesterly winds associated with a trough of low pressure. However, ocean temperatures will warm to 28°C, which may partially counteract the increase in shear, as far as maintaining a favorable environment for development. Dry air and shear may be significant enough to destroy TD 7 on Sunday, as predicted by the GFS and ECMWF models. These models tried to kill off Ernesto in a similar situation last week, so I am inclined to believe TD 7 will survive for the coming five days, but struggle. The official NHC forecast of a 45 mph tropical storm moving through the Lesser Antilles Islands Saturday night and Sunday is a reasonable one.


Figure 2. Morning satellite image of Invest 93L.

93L
A strong tropical wave in the far Eastern Atlantic that emerged off the coast of Africa Thursday night was designated Invest 93L by NHC. In their 8 am Tropical Weather Outlook, NHC gave 93L a 50% chance of becoming a tropical depression by Sunday morning. Satellite loops show a pronounced spin to the atmosphere at mid levels, but little in the way of heavy thunderstorm activity. The latest Saharan Air Layer Analysis from the University of Wisconsin shows that while the atmosphere immediately surrounding the disturbance is moist, there is a large area of dry air from the Sahara to the west and north. This dry air will be a significant impediment to development during the coming week. The ECMWF model shows some weak development of 93L over the coming week, and predicts a general west-northwesterly track. The storm may be something Bermuda needs to be concerned about in eight or so days.

I'll have a new post this afternoon.

Jeff Masters

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374. VR46L
5:19 PM GMT on August 10, 2012
Quoting 7544:
94L below cuba soon might be a spin there?

Possibly....


Link



Link
Member Since: March 1, 2012 Posts: 0 Comments: 6832
373. CosmicEvents
5:18 PM GMT on August 10, 2012
Quoting wunderkidcayman:
anyway I am going for a break but before I do I just want to say this if Ernesto can develop and become a TS and a Hurricane in a little bit worse conditions than TD7 then TD 7 sure hell can so let us sit back and watch well except those who are in the windward islands they need to keep close eye and once those watches and warning are issued then start prepairing or even prepare before the watches and warnings
Not much chance. The trek through the Caribbean will be under about as adverse conditions as you can get. If you've ever seen the movie Monty Python and The Holy Grail think of the scene with King Arthur and the Black Knight, with TD7 playing the role of the black knight.
Member Since: August 3, 2005 Posts: 10 Comments: 5527
372. OracleDeAtlantis
5:18 PM GMT on August 10, 2012
Quoting ProgressivePulse:
Afternoon All. Western Caribbean looking a little suspect this afternoon.

All except the pressure ...

Member Since: August 27, 2009 Posts: 0 Comments: 501
371. stillwaiting
5:17 PM GMT on August 10, 2012
Quoting Jedkins01:
After having a very wet June and July, we are now to date having the driest August to date in at least 10 years, which is when I first got my rain gauge....

And here I thought we were going to have a "normal" rainy season. I guess I spoke to soon. I've only had 1.4 inches of rain for all of August so far, normal to date is about 4 inches. Indeed, this too applies to much of Central and south Florida. In the earlier part of the rainy season, we would always get more rain out of events than expected across the whole area, now every rain maker or rain pattern falls short. Even with much deep moisture and instability moving into South Florida, coverage down there is much lower than you might expect, why, I do not know.

Once again I've said before, I've observed stubborn patterns that transcend traditional understanding of meteorology, in that they defy at least somewhat what you would expect from a given averaged atmospheric sounding over a region for a period of time regardless of forecast knowledge and model outputs.
Member Since: October 5, 2007 Posts: 20 Comments: 4970
370. PalmBeachWeather
5:16 PM GMT on August 10, 2012
Quoting MississippiWx:
Lol.

I see we've started the yearly ant/bird talk. Sigh. You know the blog is bored when...
Missi.......I agree with you, but it is a fact of southern living
Member Since: October 3, 2008 Posts: 0 Comments: 5820
369. GBguy88
5:16 PM GMT on August 10, 2012
Quoting 47n91w:


I don't see any spotter reports and radar is only estimating 1/2" hail, which your observation of "marble-sized" supports. Unless the branches were of size (most criteria is over 4" in diameter at their largest point), it sounds like the storm wasn't severe by definition. Certainly strong, but not strong enough to warrant a warning. Unless some delayed reports come into the NWS Office of bigger hail or wind damage.

Severe hail criteria: http://www.nws.noaa.gov/oneinchhail/index.html


They put out the "Special Statement" just after I posted that message. It wasn't severe by definition, but strong enough to warrant the alert...which wasn't issued until the storm had passed us. We might have had some two to three inch branches snapped off, but maybe not four. So no, not severe...but pretty strong for a standard afternoon storm.
Member Since: August 22, 2008 Posts: 0 Comments: 482
368. wxwonder1
5:16 PM GMT on August 10, 2012
A few days ago the CMC wanted to develop a system in the Western Carib and pull it north into the GOM. I Wonder if it has anything to do with this tropical wave SW of Jamaica??
Member Since: September 18, 2007 Posts: 0 Comments: 103
367. MississippiWx
5:15 PM GMT on August 10, 2012
Lol.

I see we've started the yearly ant/bird talk. Sigh. You know the blog is bored when...
Member Since: July 15, 2006 Posts: 17 Comments: 10159
366. NEwxguy
5:14 PM GMT on August 10, 2012
I think Im going to see flood advisories going up all over the place the next couple of days,atmosphere has a ton of moisture its holding on to,temporarily.
Member Since: September 6, 2007 Posts: 874 Comments: 15595
365. jascott1967
5:14 PM GMT on August 10, 2012
Quoting wunderkidcayman:
anyway I am going for a break but before I do I just want to say this if Ernesto can develop and become a TS and a Hurricane in a little bit worse conditions than TD7 then TD 7 sure hell can so let us sit back and watch well except those who are in the windward islands they need to keep close eye and once those watches and warning are issued then start prepairing or even prepare before the watches and warnings


The conditions ahead of TD7 are not any better and are actually worse than what Ernesto encountered. There's more dry air in front of TD7 and a ULL is racing down from the north which will cause high shear for TD7 before it makes it to the Lesser Antilles. It is extremely likely that TD7 will be destroyed before it makes it to the western Caribbean.
Member Since: August 16, 2007 Posts: 0 Comments: 607
364. PalmBeachWeather
5:13 PM GMT on August 10, 2012
Quoting Msdrown:



Yeah I see that on various documentaries and the news. They say those darn Pythons escaped from a zoo during Andrew or something. I had bad experience in Panama with African bees. I know what you mean about the evasive non native species.
Msdrown...Most of the unwanted species are from home collections that dont, didn't realize their pets would become so large, and so agressive.Now we have to deal with it.
Member Since: October 3, 2008 Posts: 0 Comments: 5820
363. 7544
5:13 PM GMT on August 10, 2012
Quoting VAbeachhurricanes:


A storm that forms into a tropical depression before 30W


oh cool thanks didnt know that
Member Since: May 6, 2007 Posts: 0 Comments: 6690
362. VAbeachhurricanes
5:11 PM GMT on August 10, 2012
Quoting BlueEyedSpirit:
What is a Cape Verde storm?

Would 93L being classified as a Cape Verde storm?


A storm that forms into a tropical depression before 30W
Member Since: September 6, 2007 Posts: 0 Comments: 6068
361. Tribucanes
5:10 PM GMT on August 10, 2012
New invest coming today, question is where?
Member Since: April 18, 2012 Posts: 0 Comments: 2437
360. ProgressivePulse
5:09 PM GMT on August 10, 2012
Quoting GTcooliebai:
Look at the blow up of convection in the Western Caribbean:



Lower Convergence:



Upper Divergence:



Wind Shear:



850 mb. vort:



TWave on the SE side of a ULL. Could be why the models are NW with 07.
Member Since: August 19, 2005 Posts: 5 Comments: 5043
359. Skyepony (Mod)
5:09 PM GMT on August 10, 2012
OSCAT of 93L
Member Since: August 10, 2005 Posts: 161 Comments: 37352
358. islander101010
5:09 PM GMT on August 10, 2012
Quoting Msdrown:


I asked that question a few daysago but no one replied. I took that as a NO.
sign.that.is.more.favorable
Member Since: September 11, 2010 Posts: 1 Comments: 4333
357. 7544
5:08 PM GMT on August 10, 2012
94L below cuba soon might be a spin there?
Member Since: May 6, 2007 Posts: 0 Comments: 6690
356. islander101010
5:08 PM GMT on August 10, 2012
moving.quick!
Member Since: September 11, 2010 Posts: 1 Comments: 4333
355. VAstorms
5:07 PM GMT on August 10, 2012
Quoting PalmBeachWeather:
I saw some wierd looking bird in the Publix parking lot last week... Looked kinda like a Mynah bird


I don't know if they are in Florida but Magpies look a lot like Mynahs and can talk as well.
Member Since: August 28, 2008 Posts: 0 Comments: 247
354. Msdrown
5:06 PM GMT on August 10, 2012
Quoting tennisgirl08:
Could TD 7 combine with the energy "blob" in the Central/Western Caribbean when he gets there?

That "blob" looks suspect to me.


I asked that question a few daysago but no one replied. I took that as a NO.
Member Since: August 1, 2012 Posts: 0 Comments: 255
353. BlueEyedSpirit
5:06 PM GMT on August 10, 2012
What is a Cape Verde storm?

Would 93L being classified as a Cape Verde storm?
Member Since: July 29, 2011 Posts: 0 Comments: 0
352. Patrap
5:05 PM GMT on August 10, 2012
Check the FRONTS and MSLP Boxes here.

Note the Turning below Cuba.

Gulf Of Mexico - Rainbow Loop


Member Since: July 3, 2005 Posts: 421 Comments: 127559
351. WhoDatRR
5:05 PM GMT on August 10, 2012
Grackle? If so, it belongs in the neighborhood. Though I doubt y'all get the flocks of thousands, as we do. Seriously, had about a thousand in my yard, a month or so ago. They're noisy as hell, and can mimic sounds like a parrot. I put out chicken feed and it's gone before my girls get a couple pecks in. They do look a lot like a Mynah. Not invasive, just inconvenient... LOL

We have a couple flocks of Alexander Parakeets, around Austin. They're not really a problem, and I actually love seeing them fly around. There was once an indigeounous parrot (Carolina parakeet), that was hunted to extinction. So, the way I see it, they alexander parakeets are just filling that void. But yeah, invasive species can be a problem.

Quoting PalmBeachWeather:
I saw some wierd looking bird in the Publix parking lot last week... Looked kinda like a Mynah bird
Member Since: August 7, 2012 Posts: 0 Comments: 15
After having a very wet June and July, we are now to date having the driest August to date in at least 10 years, which is when I first got my rain gauge....

And here I thought we were going to have a "normal" rainy season. I guess I spoke to soon. I've only had 1.4 inches of rain for all of August so far, normal to date is about 4 inches. Indeed, this too applies to much of Central and south Florida. In the earlier part of the rainy season, we would always get more rain out of events than expected across the whole area, now every rain maker or rain pattern falls short. Even with much deep moisture and instability moving into South Florida, coverage down there is much lower than you might expect, why, I do not know.

Once again I've said before, I've observed stubborn patterns that transcend traditional understanding of meteorology, in that they defy at least somewhat what you would expect from a given averaged atmospheric sounding over a region for a period of time regardless of forecast knowledge and model outputs.
Member Since: Posts: Comments:
Quoting GBguy88:
Maybe a little off topic...but we just had one Hell of a thunderstorm on the north side of Pensacola. No warnings were issued or anything. Tree limbs all over the ground, lightning popping like a strobe light, marble sized hail...obviously nobody was paying any attention to that one.


I don't see any spotter reports and radar is only estimating 1/2" hail, which your observation of "marble-sized" supports. Unless the branches were of size (most criteria is over 4" in diameter at their largest point), it sounds like the storm wasn't severe by definition. Certainly strong, but not strong enough to warrant a warning. Unless some delayed reports come into the NWS Office of bigger hail or wind damage.

Severe hail criteria: http://www.nws.noaa.gov/oneinchhail/index.html
Member Since: Posts: Comments:
next invest north of Haiti imo,should move towards the bahamas/south fl,development possible fo sho;)
Member Since: October 5, 2007 Posts: 20 Comments: 4970
12z Early Cycle NHC model tracks
Invest93

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts

Member Since: July 3, 2005 Posts: 421 Comments: 127559
We certainly don't lack vorticity this year...
Member Since: October 25, 2005 Posts: 19 Comments: 21485
Quoting RussianWinter:


Lol the Hurricane Season is never boring.

There is always some ragged-looking twave to cheer on, in the small chance of it becoming a storm.
True dat! Well said!
Member Since: Posts: Comments:
Ernesto's circulation never ended. COC was said to have died but I believe COC didn't die, it just relocated in the Eastern Pacific north of where it was. Looks like it on satellite at least. Going to be a TS again by this evening. NHC says he's just a broad circulation at this time, but I think a COC still exists and so does Ernesto.
Member Since: April 18, 2012 Posts: 0 Comments: 2437
Look at the blow up of convection in the Western Caribbean:



Lower Convergence:



Upper Divergence:



Wind Shear:



850 mb. vort:

Member Since: Posts: Comments:
12z Nogaps has TD7 heading to NC/SC 992mb

Member Since: August 19, 2006 Posts: 13 Comments: 14455
Quoting Msdrown:



So does that mean they rename now its in the PAC??


They declared Ernesto dead, so unless they reanalyze and find that he still had a low level COC, he will get a new name in the Pacific if he regenerates.

Member Since: August 26, 2006 Posts: 16 Comments: 4766
Odds are that there will be a few majors this year which will spin up between now and the end of September at some point (not suggesting that TD7 will be one of those)..........We just have to wait to see where and when.
Member Since: August 8, 2006 Posts: 0 Comments: 8787
Maybe a little off topic...but we just had one Hell of a thunderstorm on the north side of Pensacola. No warnings were issued or anything. Tree limbs all over the ground, lightning popping like a strobe light, marble sized hail...obviously nobody was paying any attention to that one.
Member Since: August 22, 2008 Posts: 0 Comments: 482
Quoting Matt74:
Been boring the past three years


Lol the Hurricane Season is never boring.

There is always some ragged-looking twave to cheer on, in the small chance of it becoming a storm.
Member Since: Posts: Comments:
Afternoon All. Western Caribbean looking a little suspect this afternoon.

Member Since: August 19, 2005 Posts: 5 Comments: 5043
Quoting mcluvincane:


Not just td7, it's the entire tropics. Not much happening this year. I honestly thought this would be a good year to track some decent cyclones. Not gonna happen
Ridiculous to make this statement before Aug 11.... lol The best of the season is usually the next 6 weeks... don't lose heart yet...

Member Since: October 25, 2005 Posts: 19 Comments: 21485
Quoting hydrus:
Amazing how quickly that convection gets going with only part of the circulation over water.



So does that mean they rename now its in the PAC??
Member Since: August 1, 2012 Posts: 0 Comments: 255
Quoting mcluvincane:


Not just td7, it's the entire tropics. Not much happening this year. I honestly thought this would be a good year to track some descent cylcones. Not gonna happen
Been boring the past three years
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I'm not seeing a whole lot of spin with TD 7... this is not a healthy cyclone at all... It's going to have a real hard time, I don't think it will strengthen much.

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Quoting PalmBeachWeather:
There are so many intrusive animals and insects here in sout Florida now..Fire ants, Iguanas, Peacock bass, Oscars, Cuban lizards, Africanized bees, Now freekin' Pythons......



Yeah I see that on various documentaries and the news. They say those darn Pythons escaped from a zoo during Andrew or something. I had bad experience in Panama with African bees. I know what you mean about the evasive non native species.
Member Since: August 1, 2012 Posts: 0 Comments: 255
Quoting PalmBeachWeather:
You got that right.....Been there.Done that
And we ain't hit the peak yet!
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Quoting hurricanealley:


Don't throw in the towel just yet! I did the same thing after Tropical Storm Edouard (2008) and look what happened.


Nice free day off work, Edouard was.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
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Quoting overwash12:
Remember,One Big Storm hitting a populated area can make for a bad year!
You got that right.....Been there.Done that
Member Since: October 3, 2008 Posts: 0 Comments: 5820
Ernesto is said to be on the path of dissipation, but those bands that have hit the Pacific have very strong, well above TS force wind with them. COC getting to the point of being dead, but new COC will form soon no doubt when Ernesto's entirety is back over water. Will get renamed, but there is an argument to be made it should stay Ernesto imo.
Member Since: April 18, 2012 Posts: 0 Comments: 2437
Could TD 7 combine with the energy "blob" in the Central/Western Caribbean when he gets there?

That "blob" looks suspect to me.
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Remember,One Big Storm hitting a populated area can make for a bad year!
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Quoting Grothar:
The GFS. I am trying to get it to come around to my way of thinking but it is stubborn.




Bet you posted Ernesto's Caribbean Cruise model to see who was paying attention. :p
Quoting hydrus:
Amazing how quickly that convection gets going with only part of the circulation over water.
Well, darn. 1000am cdt last advisory discussion on Ernesto..
...THE REMNANTS OF ERNESTO ARE EXPECTED TO MOVE OFF MEXICO INTO THE
EASTERN PACIFIC WITH THE POTENTIAL TO BECOME A TROPICAL CYCLONE. IF
THIS IS THE CASE...IT WILL ACQUIRE A NEW DEPRESSION NUMBER...OR A
NEW NAME IF IT BECOMES A TROPICAL STORM.

THIS IS THE LAST ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON
ERNESTO.


FORECAST POSITIONS AND MAX WINDS

INIT 10/1500Z 18.0N 99.2W 20 KT 25 MPH
12H 11/0000Z...DISSIPATED

$$
FORECASTER AVILA

(T-6)
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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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