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 Snowlover123:
18Z GFS takes it out to sea, and goes to town with Danielle, again, about the same as all of the other GFS model runs today.



Don't let my name fool you, I'm in the
Mid-Hudson Valley, but I do go to Long Island a lot!
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1030. will45
Quoting beell:
Maybe old news here but an addition to this page?
ecmwf-oper


very nice beell ty
Member Since: July 18, 2009 Posts: 1 Comments: 994
18Z GFS takes it out to sea, and goes to town with Danielle, again, about the same as all of the other GFS model runs today.

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Mobile Radar



Tampa Radar

Member Since: August 15, 2008 Posts: 0 Comments: 2133
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Quoting Thundercloud01221991:
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 22 AUG 2010 Time : 214500 UTC
Lat : 13:26:58 N Lon : 35:13:14 W


CI# /Pressure/ Vmax
3.1 / 998.8mb/ 47.0kt


Final T# Adj T# Raw T#
3.1 3.4 3.4

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : +1.4C Cloud Region Temp : -34.1C

Scene Type : SHEAR (0.04^ TO DG)

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF


pressure is below 1000 now


Pressure 998 mb

Weakening Flag: OFF
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Hey folks,

Does anyone know which trough (the one over the northwestern US, or the one over the norhteastern US) is supposed to bend the track of Danielle to the northwest. Tracking that trough over the next few days would help in figuring out what would happen.
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Quoting hydrus:
You guys get whacked almost every day this time of year. Is it just the daytime heating, rain machine thing?


Today was not a typical day for S.W. Florida. In my area (Ft. Myers) its been overcast all day with rain starting around 11 am this morning. Its been raining off and on all day.

Normally, the day starts out bright and sunny and then around 3-4 pm we get strong thunderstorms.

Local Meteorologist said we have a "system" over the area. I'm not exactly sure what the
"system" is.
upper level? Low level?
Member Since: Posts: Comments:
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 22 AUG 2010 Time : 214500 UTC
Lat : 13:26:58 N Lon : 35:13:14 W


CI# /Pressure/ Vmax
3.1 / 998.8mb/ 47.0kt


Final T# Adj T# Raw T#
3.1 3.4 3.4

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : +1.4C Cloud Region Temp : -34.1C

Scene Type : SHEAR (0.04^ TO DG)

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF


pressure is below 1000 now
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Member Since: August 15, 2008 Posts: 0 Comments: 2133
Quoting MiamiHurricanes09:
Not that I've seen.


We'll see if, like with Danielle, as you had mentioned earlier, if the rest of the models begin to pick up on this or not. Foul weather is heading my way- 2-5" of it.
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Latest On Danielle..Evening Video Blog
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1018. xcool
beell that new .wow
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting LongIslandXpress38:


It's been pouring on my house all day!


Same, but the Nor'Easter would also bring gusty winds to out region.

The Nor'Easter would greatly impact Long island, where you are, so get prepared! ;)



NYC would get the most rain, as well as Western Long Island.
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Quoting Snowlover123:


Interesting... but the question is, have any of the other models shown this?
Not that I've seen.
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1014. beell
Maybe old news here but an addition to this page?
ecmwf-oper
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Quoting msmama51:
What's that going on in the Gulf? Not XTD5 again? Where is it going now? We've been threatened twice now by it on the MS Gulf Coast. Third time the charm?


Should get off the pandhandle of FL in a couple of days
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Quoting weatherman566:
This was in a weather discussion from the NWS in Peachtree City in GA:

AMPLIFYING UPPER ATMOSPHERIC PATTERN BRINGING ABOUT SOME LONG
OVERDUE LARGE SCALE SYNOPTIC CHANGES. DEEPENING UPPER TROUGH ACROSS
THE NE U.S. AND AMPLIFYING UPPER RIDGE CENTRAL U.S. COMBINING TO
FINALLY PUSH A COLD FRONT INTO THE SE U.S. THIS FRONT PROMISES TO AT
LEAST TEMPORARILY BRING A REDUCTION OF TSRA TO THE CWA DURING THE
FIRST HALF OF THIS WEEK AS WELL AS LOWER DEWPOINTS. MEANWHILE...THE
REMNANTS OF T.D. NO. 5 WERE WEAKLY EVIDENT IN EC GA. THIS WEAK
CIRCULATION CENTER WILL BE PUSHED S-SW BACK INTO THE GULF DURING THE
MID AND LATER PART OF THE WEEK...AND COULD BE POISED TO BRING
SCT-NMRS SHRA/TSRA BACK TO THE CWA TOWARD THE END OF THE WEEK.




Whaaaa? The HPC surface analysis last week officially had the remnant low of TD 5 get absorbed by a front in NW Mississippi on August 18.
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Quoting MiamiHurricanes09:
Note the tropical cyclone in the BOC. The GFS has been consistent with that.


Interesting... but the question is, have any of the other models shown this?
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CV Tropical Storm Danielle:

Member Since: September 30, 2005 Posts: 0 Comments: 1606
1009. hydrus
Quoting plywoodstatenative:
What is to blame for all the instability over florida?
You guys get whacked almost every day this time of year. Is it just the daytime heating, rain machine thing?
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Quoting Snowlover123:
18Z GFS model run:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/18/index_ten_l_loop.shtml

There's also a prominent Nor'Easter affecting the Mid-Atlantic Region.



It's been pouring on my house all day!
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What's that going on in the Gulf? Not XTD5 again? Where is it going now? We've been threatened twice now by it on the MS Gulf Coast. Third time the charm?
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1005. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Member Since: August 15, 2008 Posts: 0 Comments: 2133
Tropical, add in the humidity and the heat index ranges from 104 on up
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Quoting jason2010xxxx:
tropical storm Danielle
is still moving nw wow
nope
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This was in a weather discussion from the NWS in Peachtree City in GA:

AMPLIFYING UPPER ATMOSPHERIC PATTERN BRINGING ABOUT SOME LONG
OVERDUE LARGE SCALE SYNOPTIC CHANGES. DEEPENING UPPER TROUGH ACROSS
THE NE U.S. AND AMPLIFYING UPPER RIDGE CENTRAL U.S. COMBINING TO
FINALLY PUSH A COLD FRONT INTO THE SE U.S. THIS FRONT PROMISES TO AT
LEAST TEMPORARILY BRING A REDUCTION OF TSRA TO THE CWA DURING THE
FIRST HALF OF THIS WEEK AS WELL AS LOWER DEWPOINTS. MEANWHILE...THE
REMNANTS OF T.D. NO. 5 WERE WEAKLY EVIDENT IN EC GA. THIS WEAK
CIRCULATION CENTER WILL BE PUSHED S-SW BACK INTO THE GULF DURING THE
MID AND LATER PART OF THE WEEK...AND COULD BE POISED TO BRING
SCT-NMRS SHRA/TSRA BACK TO THE CWA TOWARD THE END OF THE WEEK.


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Quoting hunkerdown:
poor Bermuda, what did it ever do to the Dynamic models...


heh heh
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Quoting Snowlover123:
18Z GFS @ 66 hours. Danielle appears as if she senses the weakness in the ridge, and is starting to turn more more NW.



The TW also degenerates into a weak area of Low P.
Note the tropical cyclone in the BOC. The GFS has been consistent with that.
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Quoting DestinJeff:
Is this something new with GFS?

no, it had it plowing into nyc 4 or 5 days ago. it seems its target when it readjusts tracks. last time it went fl-nyc-ocean. this time ocean-nyc-x. if its nyc again nnext run (or even ocean again) its worth discussing but this feels like a readjustment tweener run.
Member Since: July 23, 2010 Posts: 0 Comments: 524
18Z GFS model run:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/18/index_ten_l_loop.shtml

There's also a prominent Nor'Easter affecting the Mid-Atlantic Region.

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Quoting plywoodstatenative:
Taz, Let me put it this way. If not for the egg recall I could have scrambled eggs on someone's hood.


Is it 106 °F there?

It is here...
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What is to blame for all the instability over florida?
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Afternoon folks,

I see Danielle is in the house. Looking at the CIMSS, we have a trough over the northeast US and another over the northwest US. Which one is supposed to bend Danielle's track to the NW in the future?
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Quoting MiamiHurricanes09:
That would make my day. :)
from "you know who"...
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Quoting MiamiHurricanes09:
Some major credit has to be given to the GFS ensembles for being the first ones to hint out Danielle.


Well, it is the "new and improved" GFS, right? :P
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Quoting FLPandhandleJG:


Yep that's me... Tampa getting hammered.
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read the 11am discussion, not the mods.
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Member Since: August 15, 2008 Posts: 0 Comments: 2133
Where do you live in the Northeast buddy?
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18Z GFS @ 66 hours. Danielle appears as if she senses the weakness in the ridge, and is starting to turn more more NW.



The TW also degenerates into a weak area of Low P.
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Quoting DestinJeff:
4


Dynamic:
poor Bermuda, what did it ever do to the Dynamic models...
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Some major credit has to be given to the GFS ensembles for being the first ones to hint out Danielle.
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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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