Tropical Depression Six arrives

By: Dr. Jeff Masters , 5:14 PM GMT on August 22, 2010

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Tropical Storm Tropical Depression Six is here, but it will not be a threat to land for at least the next five days. Tropical Depression Six is a classic "Cape Verdes"-type storm common during the peak part of hurricane season. Cape Verdes-type storms are so named because they form from tropical waves that come off the coast of Africa and pass near the Cape Verdes Islands just west of Africa. Cape Verdes hurricanes are the largest and most dangerous types of hurricane in the Atlantic, since they spend a long time over water have and have of opportunity to reach full maturity. Tropical Depression Six has a ways to go before it becomes a hurricane, as the storm is embedded in a strong easterly flow of wind courtesy of the African Monsoon that is generating a moderately high 15 - 20 knots of wind shear. There is also a tropical disturbance to the northeast of TD 6 that is sucking away some moisture and is interfering with the storm's circulation. Sea Surface Temperatures (SSTs) are a warm 28°C, and the storm is embedded in a moist environment, so wind shear is the primary inhibiting factor for development. The strong east winds imparting the shear are keeping any heavy thunderstorms from developing on the east side of the center of circulation, which is exposed to view in satellite imagery (Figure 1.)


Figure 1. Afternoon satellite image of Tropical Depression Six.

Forecast for Tropical Depression Six
A ridge of high pressure will force Tropical Depression Six to the west-northwest for the next five days, and the system should increase its forward speed from its current 10 mph to 15 mph by Monday night. A powerful trough of low pressure over the mid-Atlantic Ocean will begin to pull Tropical Depression Six more to the northwest late this week, and the storm should pass well to the northeast of the Lesser Antilles Islands. It remains to be seen, however, it this trough will be strong enough to fully recurve Tropical Depression Six out to sea. The GFS predicts that Tropical Depression Six may pass close to Bermuda about eight days from now, and it is also possible that Tropical Depression Six could eventually hit the U.S. East Coast 9 - 15 days from now. However, we have no skill in making these sort of ultra-long range forecasts, and the long-range fate of TD 6 is uncertain.

Elsewhere in the tropics
The ECMWF and NOGAPS models are predicting formation of a tropical depression off the coast of Africa 3 - 4 days from now.

Jeff Masters

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There's a chance that PGI34L, if it were to develop, will dissipate in the CATL after some time.

We'll see what happens.
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No Jason, we are not going to have two fish storms.
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Quoting troy1993:
Hey Storm W if the tropical wave off the coast of Africa becomes Earl do you think it was also go out to sea?

I don't think so it will go further westward and souther than Danielle.
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Quoting Progster:
Low just N the Azores this morning has a decent subtropical feed (see: Link

and with the help of digging upper trof to its NW and an amplifying jet should bomb out over Ireland and the UK late Wednesday thru Friday. But as Michael Fish? said years ago: "it won't be a hurricane" :)


Link

Yes...

(There was a mix-up due to Floyd in 1987.)
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3178. surfmom
Quoting mrpuertorico:


:P yeah surfs up this weekend i just hope it dosnt get to big lol!


Yes, Danielle will be leaving you her dance card....LuckyMAN, those initial waves would be out of my league for sure..I'd have to wait for the left overs.
I'm curious about waves/surf in PR - are you near Rincon or Isabella ? - wondered what the wind and wave height will be....do you have a suggestion for a good local surf site to check this out? (WUmail me)
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Shear is 15-25 knots over PGI34L so any significant development would take place in the 24-48 hour timeframe which is when shear is forecast to drop some.
Member Since: July 30, 2007 Posts: 76 Comments: 4062
Danielle is developing along nicely. Already has an eye wall developing.
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Models all showing wave behind Danielle (future Earl) will not affect the CONUS either. Looks like the Cape Verdes storms this year are destined for Bermuda or the fish. Too many troughs.
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3172. smuldy
Quoting Stormchaser2007:


Night all? lol

Where are you from?
Miami Beach, land of 5am last call; and after watching the clip from empire that i just wrongly quoted i need to crash, its almost 10am and need to be up for work by 4.
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Quoting Stormchaser2007:
Ill go out on a limb and say that this will be a depression in 48 hours. It has that look.



Already at 10% per NHC so it isn't out of the question.
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3168. Relix
Pre-Earl will be the one to watch for us in the islands. Looks mighty dangerous.
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Quoting mbjjm:
Convection fully wrapped around the center, but a little spotty on the eastern side of the system.








Even Cat 1's have that issue so it is not surprising.
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PREDICT DAY 1 (Next 24 hours) Outlook:

PGI30L difficult to track in most ensemble members. Only a
handful of members are still following the system; most others
detect larger circulation values away from the system. The
ensemble suggests a slower rate of intensification for Danielle
over the next day. Almost all members keep the system below TC
strength during the period. PGI34L emerges from the lateral
boundaries as a fairly significant circulation and 30% of
members with OW values greater than 2. As I stated above, I do
not put much faith in this forecast due to its initial position.
The circulation over the Gulf and Florida shows little change
in strength or position.
Member Since: July 30, 2007 Posts: 76 Comments: 4062
Quoting Bobbyweather:
Hi. I have a question, but in PGI34L, what does PGI stand for? Also I found a site http://www.nrlmry.navy.mil/predict-bin/tc_home2.cgi and looked in the archive, but there's no 01L.PGI01L, 02L, 03L, ..., 15L.PGI15L. Can somebody explain why?

Pouch Guidance Investigation
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Ill go out on a limb and say that this will be a depression in 48 hours. It has that look.

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3162. Bayside
Quoting homelesswanderer:


I think NASA has a different study going on this summer. That may be it?


I think my father metioned being involved in this. I can't remember the details but for some reason I feel like they were flying out of Houston. Will see if I can get some more info. Think he is heading down there next week.
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Quoting smuldy:
Impressive, most impressive, but you are not a hurricane yet.

Night all


Night all? lol

Where are you from?
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Good Morning Everyone!

Looks like the long awaited turn to the west finally materialized. It had to...the ridging was fairly strong due north of it.

The NHC's cone is of course smoothed, so Danielle will move south of the cone until around 45-50W then curve back towards the cone as the forecast weakness materializes.

It also appears they're a little slow with the forward motion. Probably will be reconciled at the 11AM update.

I'm still interested to see how far south and west this thing gets while the ridging is strong.

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3158. SLU
You don't see such a powerful looking wave along the African Coast everyday.

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3157. smuldy
Quoting Stormchaser2007:
Impressive

Impressive, most impressive, but you are not a hurricane yet.

Night all
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Quoting CybrTeddy:
Anyone want to guess on the 11 am advisory? I'd say 65 mph 994 mb pressure.


i don't know about that at this rate of strengthening and looking at the sat pic id say 70 mph strong TS.
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Low just N the Azores this morning has a decent subtropical feed (see: Link

and with the help of digging upper trof to its NW and an amplifying jet should bomb out over Ireland and the UK late Wednesday thru Friday. But as Michael Fish? said years ago: "it won't be a hurricane" :)
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Quoting Stormchaser2007:


Morning! Shouldn't be too long before an eye pops out on visible, we might have Hurricane Danielle before the day's up.
Member Since: July 30, 2007 Posts: 76 Comments: 4062
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Quoting Stormchaser2007:
65-70 mph is a good bet.



it looks like an eye is trying to pop out there
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Quoting Stormchaser2007:
Impressive



Developing Hurricane..
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65-70 mph is a good bet.

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I sure understand your frustration, Storm. I know next to nothing about nothing. On the other hand, I don't pretend to forcast. The only thing I can add is a sometimes humorous comment, and try not to do it when y'all have an actual storm to talk about. That may be 'lame', but life without something to laugh about is worse.

I deeply appreciate your time and expertise, and the generosity of all the experts on the board. Just being able to ask questions of the folks who know what they are talking about is a real gift. I am not seeing as many of them as I used to, and that distresses me.

There's been a lot of verbal abuse on here this year. MUCH more than I've ever seen, and I understand the desire to limit the ability to post based on the lack of sense that's been demonstrated. I'd hate to not be able to ask the questions, tho.

Thanks again for your patience and your blog which I always read, even when I don't understand all of it! :-)
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Quoting surfmom:
Interesting forecast/observation from the Surfer Perspective - This guy is also seeing what Stillwaiting mentioned in an earlier post.
AURASURF/MICAH WEAVER/swfl GOMEX
Some junky knee high waves on local beach today. Maybe bigger elsewhere but I doubt it buoy is only 2ft as of now. Very rainy last night and over 2 inches fell here in St Pete. There is a 1009mb low in the gulf that will strengthen and torque a little bit so all you kids will go back to school with waves at the beach... Come on you can't skip the first day of school to go surfing. Hahaha. Respect your elders. Tuesday will be 'ol fart surfing day'. Looks waist high from the SW and choppy on Tuesday as that low starts to move N. Still a bump left for Wednesday: knee to thigh. Kids can surf after school.
Ahhh el Atlantico... starting to come to life. Looks like a pattern change in the long run.. Seems a little early but tons of east flow starting Friday. Kinda back door front looking as the whole ATL gets NE wind later in the period. Maybe we will get cooler breezy WX here in FL. Too bad the EC is going to be all choppy for this next swell. PR is gonna get the goods. East swell will go NE and be met by light SE winds so Next weekend looks real good down on the Isla del Encanto.
Have a good one!


:P yeah surfs up this weekend i just hope it dosnt get to big lol!
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Wow that tropical wave coming off Africa is mighty impressive.
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3145. SLU
Quoting tropicfreak:


Very impressive sat pic. Convection is beginning to wrap around the center.


Yep
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Quoting Canesinlowplaces:
I was reading somewhere that they were going to be tying out a drone this year that could stay in storms for 15 hours. I think that was out in CA though, so they may be trying it on EPac storms - anyone have additional info?


GRIP Website
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Well, on the model output, the pressure was 994mb.

The pressure on the earlier advisory was 997mb.
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Impressive

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I did have the pleasure of working on both the Gemini and Apollo projects for NASA subcontractors and am proud to have been involved in the technology that came from those projects. All things considered, Mother Nature will behave as she damn well pleases. Keep up the great work.

Sir it was your generation that did the pioneering work that gave us these fine tools for increasing our knowledge perhaps beyound where your generation even imagined in the 50's and 60's. You actually did something to contribute to every discussion that will ever take place here and every forcast that will ever be given again. I see most of these hypesters that constantly post their "forcast" using the tools that people like you help build. I apprecitate pro's like StormW and Dr. Masters giving us their time. Millions of people visit this site each year to learn important information about these storms. I hope the resourse in continued.
Thank you.
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Quoting CybrTeddy:
Anyone want to guess on the 11 am advisory? I'd say 65 mph 994 mb pressure.


I'd surely agree with that seeing the center under the canopy, May see a Hurricane later today if indeed shear subsides.
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3138. smuldy
Quoting Neapolitan:


Again, this is because we adults share this forum with a lot of first- and second-graders; they get their feelings hurt when someone attempts to reason with them, and they start hitting the minus button, the ignore link, or--more and more frequently--the red exclamation button. It's to be expected; I'm sure they throw the same red-faced, floor-banging, door-kicking, breath-holding temper tantrum every time their mommy and daddy tell them to brush their teeth or go to bed.

By the way, if this doesn't apply to you, the reader, you won't be bothered by it. If you are bothered by it, well, we likely already knew you would be... ;-)
very last post today;
reported! lol j/k
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StormW,

Never read your synopsis before, just hated clicking around to other sites, but I gotta say, this mornings readings while sippin on my coffee was about the best reading I've had yet! Thank you to keeping an open mind on the "machine" that we have working over the US and into the Atl. if this don't work together, N may be out of the directional pattern. THANKS AGAIN, GREAT WRITEUP, LOOK FORWARD TO IT EVERYDAY NOW! Thank You
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I would say they go to 70 mph with a pressure of 990
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Quoting CyclonicVoyage:



Not a relocation. Late last night, 12am EST or so, it appeared that the center was being pulled WSW into the convection. Without visible confirmation though, that's a tough call, especially with a cloud canopy such as Danielle's. MIMIC was old at the time as well and suggested nothing. MIMIC & Visible this morning that it indeed was sucked into the convection and is presently working on a complete eye wall.


Okay, that makes a little more sense thanks for clarifying.
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3134. mbjjm
Convection fully wrapped around the center, but a little spotty on the eastern side of the system.






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Impressive

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Anyone want to guess on the 11 am advisory? I'd say 65 mph 994 mb pressure.
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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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