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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the stronger the storm the more west movement?
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where are you? the howling finally stopped here. i'm in brusly (west baton rouge)


I'm in Houma, it's storming here.
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Quoting LADobeLady:


The winds are ripping, more from this that we got from TD5 and XTD5


where are you? the howling finally stopped here. i'm in brusly (west baton rouge)
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Nice blog, Kori.
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Quoting txsweetpea:

It is NOT impossible for this to go further west ...I agree with you and there have been alot of storm tracks that have. I do realize that it all depends all depends onthe strength of Danielle and the troughs /ridging. If the troughs/ridging dont move according to planned this could play an important role also.


There's nothing blocking it from continuing west, AFAIK. The poleward movement predicted is, as you said, because of troughs.

That doesn't mean that Danielle CANT go west, it simply means that the more probable outcome will be poleward.
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Houma La here It is kicking outside tonight
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2276. smuldy
I'll go against the crowd. This is speculation this far out especially given model continuity, but I still refuse to buy a trough that deep and strong in August. IF the storm ramps up by tomorrow it could very well use its outflow to STRENGTHEN the ridge to its north. Given that the models forecast nearly a northerly movement from where it is, AND that even the NHC concedes it will head WNW for the next 48 hours, I find it highly troubling to call the models reliable as yet. Should the storm defy expectations, continue to feel a weakness to its north in the ridge, and should the ridge of high pressure break apart allowing a giant august nor'easter to form allowing a trough of low pressure to dip to 20n then the models will verify. At this time I have about 25% confidence of that happening. Where it goes will depend entirely on which components pan out and which do not, but until it recurves, or until the ridge weakens or splits, or until the large trough dips down at such an enormous strength, this needs to be watched by just about everyone on the Atlantic coastline or in Bermuda. Tropical cyclones are very difficult to predict, but given the number of extremely unusual components factored into the model forecast runs and given the current conditions showing little sign that these anomalies are shaping up save for computer runs, I feel this may well be the storm that models have the toughest time getting a handle on for this entire season in so far as track. Everyone should pay attention closely over the next few days to a)strength of the cyclone and its outflow b)latitude c) the mid atlantic ridge and d)any trough split around georgia sending a non tropical low pressure system up the us east coast, as these will be the key factors in the storms track.
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Quoting cirrocumulus:
It seems the center of Danielle may relocate to the southeast. It is still in the early stages.


the circulation is very strong, a relocation is unlikely at this stage
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anyway guys I am off till early morning I will see what our TS is doing
Member Since: June 13, 2009 Posts: 2 Comments: 12719


We need to watch these time frames. If Danielle is delayed one day by a point on this graphic she might miss her point of parking and ask for a more upscale landfall and cost a lot more.
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2271. HadesGodWyvern (Mod)
** WTPQ20 BABJ 230300 ***
SUBJECTIVE FORECAST
TS MINDULLE 1005 (1005) INITIAL TIME 230300 UTC
00HR 16.1N 110.4E 988HPA 20M/S (40 knots)
30KTS 100KM
P12HR WNW 15KM/H=

China Meteorological Administration
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2269. awp5141
Link
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Member Since: August 15, 2008 Posts: 0 Comments: 2133
It seems the center of Danielle may relocate to the southwest. It is still in the early stages.
Member Since: September 30, 2005 Posts: 0 Comments: 1606
Quoting CyclonicVoyage:


Looks like a gust front developed out ahead of the storm complex, straight line winds.



The winds are ripping, more from this that we got from TD5 and XTD5
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Quoting Neapolitan:


Well, what is BR? Boca Raton? Baton Rouge? Brazil? Banana Republic?


LOL! sorry i didn't realize that i put BR. that was silly. Baton Rouge. i really haven't heard wind like this except during canes. it's really strange that the local channels aren't saying anything. there is no rain, just constant howling winds and a little thunder in the distant north.
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Don't forget about the wave behind Danielle. It's father south and could sneak up on some people.





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Quoting KoritheMan:
For those interested, I just wrote a blog on Danielle.

Always interested!
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goodnight everyone cant wait until morning to see Danielle lol :) nite
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Quoting truecajun:
seiously. the north winds are literally howling. the cat is freaking out. of course, the local channels aren't telling me anyhting.


Looks like a gust front developed out ahead of the storm complex, straight line winds.

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2260. Halyn
Thank you, Dan .. :)
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Quoting crashingwaves:



I agree here, no one knows for sure what's going to happen down the road. Even jeff Masters quoted as saying "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. So nothing is certain at this point, I've seen the models predict this and that, only to see a storm barreling down on us. I say wait & see if the 2 troughs will steer Danielle out to sea.jmo

Absolutely right!
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Quoting MississippiWx:
I'm out, everyone. Don't let the GFS put Danielle on our doorstep next week. Night.

Goodnight!
Member Since: August 15, 2008 Posts: 0 Comments: 2133
Quoting Halyn:
Would someone please post a pic of her area so she can see what is happening ?


Well, what is BR? Boca Raton? Baton Rouge? Brazil? Banana Republic?
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Quoting Halyn:
Would someone please post a pic of her area so she can see what is happening ?


Heavy line of thunderstorms coming through. Looks to passing pretty quickly.

Member Since: August 22, 2008 Posts: 12 Comments: 6010


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Ho77ywood..

Yeah same here.. but it didnt start 12:30 in the afternoon.. then off and on til like 6ish.. Had a nice storm came through around 4 when I went to BestBuy today.. I think I will get more rain tomorrow like I did the last few days or so..
Member Since: August 15, 2008 Posts: 0 Comments: 2133
Quoting CyclonicVoyage:


I use IKE as an example because Broward EOC was fully activated on high alert and briefing the public on near future EVAC orders due to CAT 4 IKE's arrival, oops.

It is NOT impossible for this to go further west ...I agree with you and there have been alot of storm tracks that have. I do realize that it all depends all depends onthe strength of Danielle and the troughs /ridging. If the troughs/ridging dont move according to planned this could play an important role also.
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Storms are getting nasty here in Houma but man does that cool breeze feel good.
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Quoting Halyn:
Would someone please post a pic of her area so she can see what is happening ?


yes. please do.
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Quoting txsweetpea:


EXACTLY...thannnnk you!


I agree here, no one knows for sure what's going to happen down the road. Even jeff Masters quoted as saying "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. So nothing is certain at this point, I've seen the models predict this and that, only to see a storm barreling down on us. I say wait & see if the 2 troughs will steer Danielle out to sea.jmo
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I'm out, everyone. Don't let the GFS put Danielle on our doorstep next week. Night.
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2245. awp5141
Link
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2243. Halyn
Quoting truecajun:
i'm starting to get scared over here. it sounds like a hurricane outside. the wind is going NUTS. what is going on?? anyone else in teh BR area?
Would someone please post a pic of her area so she can see what is happening ?
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Thats sum heavy dry air.. ^^^
Member Since: August 15, 2008 Posts: 0 Comments: 2133
2241. Seastep
Off to bed. FWIW, NHC is currently predicting due W movement until 2AM EDT.

Personally looks like a hedge to me... and rightly, imo, believing the true center is on the 23/0600 point.

Think the automated is having problems with the anti-cyclone.

Click to refresh, so you have the points I speak of. Hit Trop Pts at the top.

Link
Goodnight all.
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Quoting Hurricanes101:


dont be so sure of that

consensus has it SE of Bermuda in 5 days, I think that most of us can agree on, after that it has just as good of a chance of heading towards the west and impacting Bermuda than it does going straight north and out to sea
I never said I was sure. In fact, I've said many times in the past that there are no certainties in this science. But, if betting was available, I'd definitely bet against a hit on a pip like Bermuda in the middle of the ocean. Just going by NHC aided long-term probability, a hit within 100 miles of Bermuda has to be in the 5-10% range.
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Quoting txsweetpea:


EXACTLY...thannnnk you!


I use IKE as an example because Broward EOC was fully activated on high alert and briefing the public on near future EVAC orders due to CAT 4 IKE's arrival, oops.
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seiously. the north winds are literally howling. the cat is freaking out. of course, the local channels aren't telling me anyhting.
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Quoting FLPandhandleJG:
lol Ho77yw00d.. so how was ur weather today? anything interesting or just normal..


rain rain rain here in fort myers!! I love the rain so didnt bother me much other then that it just RAINED lol
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2236. xcool
..RAMSDIS Online ..

Danielle move wnw at 12mph.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting PcolaDan:


I think he posted a picture.


ok
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2233. pottery
I'm out.
Thanks for the Info, the Laffs, the Bacchanal......
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2232. xcool
JLPR2 lol
Member Since: September 26, 2009 Posts: 2 Comments: 15684

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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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