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 PcolaDan:
Hey you we are getting "Rocked" over here in Mobile right now.... I just got back my internet and power keeps going and coming from this 4" an hour Storm....

Taco :o)
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Whats that mess rolling off the coast of Africa behind Danielle?
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Texas Hoosier: I thought the consensus model tracks of a few days ago seemed reasonable. However, there have already been delays. Danielle may move farther south than was first expected. StormW wrote about the NAO and how these troughs are going to be slightly weaker which can influence the track.
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Quoting NOLALawyer:
Gloria?

Floyd.
Looked a little like Gloria..:)
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I wonder if the shear will keep it weak for the next 48 hours..
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting DestinJeff:
Commence ramp-up.


Your Funny
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Hades the next time you post, please state the name of the storm. I thought that was something else. Was like WHAT she intensified that much
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874. xcool


Danielle
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting RitaEvac:
Expect major shift west in coming days as ridge will be building in down the road. Remember Andrew track, and remember Ike track. Major implication changes are underway my friends. This marks the beginning of the wild ride to the heart of season of chaos and destruction


So this thing might end up in the gulf?
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871. A4Guy
Quoting moonlightcowboy:



Would tend to agree. NHC should be making the call to TS if they haven't already, and it won't be long before it gets to cane status. Apparently, the easterly shear has relaxed and 06 is not churning the storms up, high over the coc.


Ummmm...NHC already named it...about 45 mins ago.
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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 22 AUG 2010 Time : 204500 UTC
Lat : 13:23:00 N Lon : 35:03:34 W


CI# /Pressure/ Vmax
3.0 /1000.0mb/ 45.0kt


Final T# Adj T# Raw T#
3.0 3.2 3.4

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -6.0C Cloud Region Temp : -31.1C

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 : 0.5T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
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E D I T

Quoting RitaEvac:
Expect major shift west in coming days as ridge will be building in down the road. Remember Andrew track, and remember Ike track. Major implication changes are underway my friends. This marks the beginning of the wild ride to the heart of season of chaos and destruction



Would tend to agree. NHC should be making the call to TS if they haven't already, and it won't be long before it gets to cane status. Apparently, the easterly shear has relaxed and 06 is NOW churning the storms up, high over the coc.
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Quoting TexasHoosier:
Seems to me that the key to Danielle and the possible TD behind it becoming REAL problems in the next 5-7 days is in the hands of that second sub-tropical ridge that could cause TS Danielle and the future TD/TS to stay south of the 20 Degree North Latitude line before they get to around 70 Degrees West Longitude. Over the last 5-10 years, that has a been one of the key litmus test for me, is (1) how far north is the storm before it gets to the 70 Degree West Longitude line and what is its bearing at that point. A bearing that is around 270-290 Degrees at that point is usually not a good thing. Also, a sub-tropical ridge to the north just adds to the problem, because it may force the storm below Hispanolia and Cuba or put it thru the Florida Straits where all hell then breaks loose.

Anybody want to venture a guess as to whether that second ridge that is building to the north is powerefull enough or can get in position quick enough to keep one or both of these systems tracks far enough to the south where they will enter the GOM? What would be the key day from now for either system that would be the critical point of departure for this action to happen? Anyone want to venture a guess????


it would take a sea going tug boat to pull it that far south
Member Since: July 18, 2009 Posts: 1 Comments: 994
Quoting srada:
Good Afternoon Everyone,

I have been through many hurricanes, TS and Depressions growing up on the coast of NC and I just wanted to post this excerpt from one of the discussions of Hurricane Floyd..sound familiar?

BEYOND 72 HRS...THE FORECAST UNCERTAINTY INCREASES CONSIDERABLY
AS THE NEXT MID-LEVEL TROUGH APPROACHES THE EASTERN U.S. AND
WEAKENS THE RIDGE.



the NHC were hoping the same thing that Floyd would get picked up as well..sound like the same setup with TS Danielle and well Floyd didnt recurve..best to not think this is an out to sea scenario just yet
Most of the bloggers here know unpredictable tropical cyclones are. You are right though, it is way to early to say that Danielle will not hit the U.S. There are forecasters here that say this absolutely, positively, without question will be a concern only to marine interests.
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Well, Danielle is going to kick off the severe hurricane season ahead of schedule and ahead of the NFL regular season. The models keep showing another big blocking ridge developing that may cause trouble!
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hey everyone..
Member Since: August 15, 2008 Posts: 0 Comments: 2133
Quoting stillwaiting:
Interesting cyclonic rotation near tampa bay,should move offshore tonight and i suspect could be the beginning of some gom brew!!!!!,maybe......
there was a model predicting a storm to form in the gulf in 3 days just cant remember which one
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Seems to me that the key to Danielle and the possible TD behind it becoming REAL problems in the next 5-7 days is in the hands of that second sub-tropical ridge that could cause TS Danielle and the future TD/TS to stay south of the 20 Degree North Latitude line before they get to around 70 Degrees West Longitude. Over the last 5-10 years, that has a been one of the key litmus test for me, is (1) how far north is the storm before it gets to the 70 Degree West Longitude line and what is its bearing at that point. A bearing that is around 270-290 Degrees at that point is usually not a good thing. Also, a sub-tropical ridge to the north just adds to the problem, because it may force the storm below Hispanolia and Cuba or put it thru the Florida Straits where all hell then breaks loose.

Anybody want to venture a guess as to whether that second ridge that is building to the north is powerefull enough or can get in position quick enough to keep one or both of these systems tracks far enough to the south where they will enter the GOM? What would be the key day from now for either system that would be the critical point of departure for this action to happen? Anyone want to venture a guess????
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857. HadesGodWyvern (Mod)
FKPQ30 RJTD 221800
TC ADVISORY
DTG: 20100822/1800Z
TCAC: TOKYO
TC: NIL
NR: 3
PSN: N1600 E11210
MOV: W 08KT
C: 996HPA
MAX WIND: 30KT
FCST PSN 6HR: 23/0000Z N1620 E11105
FCST MAX WIND 6HR: 35KT
FCST PSN 12HR: 23/0600Z N1635 E11035
FCST MAX WIND 12HR: 35KT
FCST PSN 18HR: 23/1200Z N1750 E10850
FCST MAX WIND 18HR: 40KT
FCST PSN 24HR: 23/1800Z N1750 E10855
FCST MAX WIND 24HR: 40KT
RMK: NIL
NXT MSG: 20100823/0000Z =

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Quoting NOLALawyer:


Hurricane Floyd?
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Interesting cyclonic rotation near tampa bay,should move offshore tonight and i suspect could be the beginning of some gom brew!!!!!,maybe......
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Gloria?

Floyd.
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Quoting DestinJeff:
Are there any other horrific storms of the past that we can compare Danielle to?


Wink...is the correct answer...Frances?
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Why has my comment been removed.
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Quoting MiamiHurricanes09:
Charley, Ivan, Georges...

Ok, I'm out. Lurk mode.


Add Hugo to the list
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Quoting xcool:
Hey Xcool, I dont know much about steering maps. Is that one you keep posting, have Danielle keep going W?
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This is gloria

http://en.wikipedia.org/wiki/File:Gloria_1985_track.png
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FEMA will stagger to knock on the door, as they will be literally bankrupt

They are damn close right now.
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ant idea where she's heading yet?
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Quoting RitaEvac:
Expect major shift west in coming days as ridge will be building in down the road. Remember Andrew track, and remember Ike track. Major implication changes are underway my friends. This marks the beginning of the wild ride to the heart of season of chaos and destruction

OMG..well aren't you just the little ray of sunshine??? Chaos and destruction??? No way I would ever wishcast that one anyone anywhere after enduring destructive Florida hurricanes.
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845. srada
Good Afternoon Everyone,

I have been through many hurricanes, TS and Depressions growing up on the coast of NC and I just wanted to post this excerpt from one of the discussions of Hurricane Floyd..sound familiar?

BEYOND 72 HRS...THE FORECAST UNCERTAINTY INCREASES CONSIDERABLY
AS THE NEXT MID-LEVEL TROUGH APPROACHES THE EASTERN U.S. AND
WEAKENS THE RIDGE.



the NHC were hoping the same thing that Floyd would get picked up as well..sound like the same setup with TS Danielle and well Floyd didnt recurve..best to not think this is an out to sea scenario just yet
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Quoting NOLALawyer:
Gloria?
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843. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15603
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Quoting Neapolitan:
I'd lay good money this will get some interest tomorrow...

Click for larger image:
Should it? Yes. Will it by the NHC? Prolly. Will it here? Doubt it. I think we are in for a tunnel vision focus on track and intensity arguments over the next few days as the models continually defy what environmental conditions imply the storm should do, and may have many a Colin like flip flops on the where and how strong.
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Quoting Neapolitan:
I'd lay good money this will get some interest tomorrow...

Click for larger image:
That is the one that I think will cause the most trouble.
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http://en.wikipedia.org/wiki/Hurricane_Danielle
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Quoting RitaEvac:
Expect major shift west in coming days as ridge will be building in down the road. Remember Andrew track, and remember Ike track. Major implication changes are underway my friends. This marks the beginning of the wild ride to the heart of season of chaos and destruction

it wont go that far south Georgia,S. Carolina, maybe Jacksonville IMO
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Ike, whats the history on this storm name?
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I'd lay good money this will get some interest tomorrow...

Click for larger image:
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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.