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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Quoting hydrus:
The CMC has some interesting high pressure scenarios...Link
"poof!"....oh thats me...:)
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From Doc MHowever, we have no skill in making these sort of ultra-long range forecasts,

Honesty is the best policy...
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Quoting HurricaneSwirl:


We discussed that earlier, and found that the ECMWF has the high resolution needed to accurately show the minimum central pressure in tropical cyclones. Unlike the GFS, when the Euro shows a 932mb system, it means 932. Source

However I'm pretty sure I'm on your ignore, so this is information for anyone lol.
They're several global models of a resolution similar to the ECMWF that can't accuratly depict central pressures, so I really don't believe that article. We shall see.
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475. DestinJeff 7:57 PM GMT on August 22, 2010

not until after I responded and yea Koritheman did that lol
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Quoting Dropsonde:
I'd say 50% chance of a significant impact on Bermuda, including the possibility of a direct hit, or a sideswiping from either the east or the west. This is going to be a big bad hurricane once it reaches those longitudes, and its size and strength will make it hard to avoid significant impacts.

20% recurvature east of Bermuda with minimal effects on the island. This would have been a higher number a few days ago, but I think it is becoming progressively more unlikely.

30% likelihood of a significant impact on the U.S. or Canada including, IMO, a 10-15% chance of a direct hit somewhere. Since the G-word is beginning to be brought up, I'm going to say, less than 1% chance of that happening. Absolutely nothing has shown it, not even that run of almost a week ago that showed a Florida hit. Not happening. And no wishcasting from me; I live in a Gulf state.
I agree, This will be a large and intense hurricane. Especially after it slurps up all that warm water...
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IMO

Recurvature east of Bermuda - 10%

Direct Hit on Bermuda - 20%

Recurvature west of Bermuda - 50%

Hit on USA - 20%
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everyone from Florida and along the eastern seaboard needs to watch TD 6 in the coming days, we could potentially have a major hurricane nearby, hopefully it recurves out to sea
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465. DestinJeff 7:54 PM GMT on August 22, 2010

Im not the one who posted that yesteday
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Quoting HurricaneSwirl:


We discussed that earlier, and found that the ECMWF has the high resolution needed to accurately show the minimum central pressure in tropical cyclones. Unlike the GFS, when the Euro shows a 932mb system, it means 932. Source

However I'm pretty sure I'm on your ignore, so this is information for anyone lol.


Be fairly unlikely to reach Category 5 at that latitude outside the GoM anyway. Off the top of my head, I suspect Dog of 1950 would be the closest. Measurements of wind speeds were not entirely spot on back then, either.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting sammywammybamy:


KA-POOF.


He/She was asking a question!

Stop poofing people for no reason!
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468. IKE
Quoting DestinJeff:


Surprised we don't have more NOGAPcasters on.


That's the 6Z run...12Z never has finished...stopped at 12 hours.

Quoting tropicfreak:


Why does the nogaps keep this thing tracking generally west??


Stronger high. That's the 6Z run.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
I'd say 50% chance of a significant impact on Bermuda, including the possibility of a direct hit, or a sideswiping from either the east or the west. This is going to be a big bad hurricane once it reaches those longitudes, and its size and strength will make it hard to avoid significant impacts.

20% recurvature east of Bermuda with minimal effects on the island. This would have been a higher number a few days ago, but I think it is becoming progressively more unlikely.

30% likelihood of a significant impact on the U.S. or Canada including, IMO, a 10-15% chance of a direct hit somewhere. Since the G-word is beginning to be brought up, I'm going to say, less than 1% chance of that happening. Absolutely nothing has shown it, not even that run of almost a week ago that showed a Florida hit. Not happening. And no wishcasting from me; I live in a Gulf state.
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Quoting HurricaneSwirl:


We discussed that earlier, and found that the ECMWF has the high resolution needed to accurately show the minimum central pressure in tropical cyclones. Unlike the GFS, when the Euro shows a 932mb system, it means 932. Source

However I'm pretty sure I'm on your ignore, so this is information for anyone lol.


By the way the page the source is on is rather long, so type Ctrl-F to bring up the find bar, and type in "european model" and it will bring you right to the paragraph that says:

"The European model is also forecasting that the trough of low pressure will miss this tropical cyclone and the Euro model also implies an eventual threat to the US Southeast coast as we head towards the Labor Day weekend. It should be noted that the European model is forecasting that Danielle may be a 940 millibar hurricane in 10 days. The European model now has the resolution to be able to predict central pressures of hurricanes since the last upgrade of the model."
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Quoting FLdewey:
At least we'll get some waves from her... time to dust off the board.


exactly haha cant wait
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TD-6 is pulling moisture back from the disturbance to the northeast.
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Quoting HurricaneSwirl:


We discussed that earlier, and found that the ECMWF has the high resolution needed to accurately show the minimum central pressure in tropical cyclones. Unlike the GFS, when the Euro shows a 932mb system, it means 932. Source

However I'm pretty sure I'm on your ignore, so this is information for anyone lol.


Thanks for the info...LOL
Member Since: May 28, 2008 Posts: 38 Comments: 5303
Quoting CybrTeddy:
ECMWF produces a 932 mb cane, probably 10 mb lower in pressure. Probably a Category 5. Right on top of Bermuda.



We discussed that earlier, and found that the ECMWF has the high resolution needed to accurately show the minimum central pressure in tropical cyclones. Unlike the GFS, when the Euro shows a 932mb system, it means 932. Source

However I'm pretty sure I'm on your ignore, so this is information for anyone lol.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
455. DestinJeff 7:50 PM GMT on August 22, 2010

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Ugh I hate when the NHC floater back updates..
COC no longer exposed.

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06L's organizing. Very cold cloudtops.
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Quoting IKE:


Why does the nogaps keep this thing tracking generally west??
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Quoting DestinJeff:


+1 for perfect spelling.
The CMC has some interesting high pressure scenarios...Link
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Quoting btwntx08:
Quoting IKE:


They're similar at 168 hours...

GFS...near 32N and 62W...



ECMWF...near 30N and 58W...


big fish storm..


dude if hits berumda it isnt and then you will be eating crow


He seems to not realize that the ECMWF takes this basically right over Bermuda

ignorance is bliss I guess
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except they can also fly out of the carribean, not just out of home base GOM
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Quoting CybrTeddy:
ECMWF produces a 932 mb cane, probably 10 mb lower in pressure. Probably a Category 5.




ouch
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444. xcool
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this playinhg a round with you IKE
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441. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
ECMWF produces a 932 mb cane, probably 10 mb lower in pressure. Probably a Category 5. Right on top of Bermuda.

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439. xcool
btwntx08 ha
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Quoting btwntx08:
Quoting IKE:


They're similar at 168 hours...

GFS...near 32N and 62W...



ECMWF...near 30N and 58W...


big fish storm..


dude if hits berumda it isnt and then you will be eating crow



no no crow is no longr a word we can ues you now most say raw fish
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Quoting MississippiWx:


This is a big storm, and convection re-flaring at COC. Once the convection collapses we could have an eye.
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Quoting duajones78413:
Looks like the models shifted west. What are the chances of this thing getting into the Gulf?

Cuajones
Probably about zero.
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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.