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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2932. Vero1
Member Since: July 21, 2008 Posts: 4 Comments: 2233
Quoting MoltenIce:
10% - blob near Cape Verde
1. AN AREA OF DISTURBED WEATHER LOCATED NEAR THE WEST COAST OF AFRICA
IS ASSOCIATED WITH A TROPICAL WAVE. SOME SLOW DEVELOPMENT OF THIS
SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS IT MOVES
WESTWARD NEAR 15 MPH. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

wow Ike beat me to it...


Lol. He's fast. I'm always late with everything. :)
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Quoting Chicklit:


Interesting, CI... Dr. Masters will probably post new blog by about 9.
The one at 10% is looking pretty good right now but don't know how it will hold up throughout the day.
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2929. scott39
I dont have a whole lot of confidence in this first trough pulling on Danielle that much. Of course this is what im reading. Im not a forecaster. Hopefully they are right on the second Trough. We will see.
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?
Well my freind, I learn all I can from reading your's and Levi's post. I try to avoid blanket statements and I try to avoid stirring the pot although I do like to have fun with my friends - but never in a mean spirit.
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As I mentioned ACE with Danielle and Bonnie and as a few people have asked about how to calculate ACE in the past, here's the quick (and lazy) version:

The formula is easy enough to find, but here's the already calculated version. ACE is calculated with 4 6-hourly advisories a day. Simply put, 5am/pm and 11am/pm.

Systems below 35kts/40mph do not count. Subtropical systems do not count. Special advisories or updates beyond these 6 hourly advisories do not count.

Per knots:

35kts/40mph – 0.1225
40kts/45mph – 0.1600
45kts – 0.2025
50kts – 0.2500
55kts – 0.3025
60kts – 0.3600
65kts/75mph – 0.4225
70kts – 0.4900
75kts – 0.5625
80kts – 0.6400
85kts – 0.7225
90kts – 0.8100
95kts – 0.9025
100kts/115mph – 1.000
105kts – 1.1025
110kts – 1.2100
115kts – 1.3225
120kts – 1.4400
125kts – 1.5625
130kts – 1.6900
135kts – 1.8225
140kts/160mph – 1.9600
145kts – 2.1025
150kts – 2.2500
155kts – 2.4025
160kts – 2.5600
165kts/190mph – 2.7225

So, per kts given on each 6 hourly advisory use that decimalised number. Then, for a storm over its lifetime, simply add together each 6 hourly number. Et voila!
Member Since: August 23, 2008 Posts: 7 Comments: 5300


Interesting, CI... Dr. Masters will probably post new blog by about 9.
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?


Storm, there are people like yourself on here that take the time out of your day to answer questions, give forecasts and help share the power of knowledge to many people. I think that is a good thing right or wrong I appreciate the time and commitment people like you give to this blog.
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hey nrtiwlnvragn this would support my idea of the COC located at 14.5N 38.5W
Member Since: June 13, 2009 Posts: 2 Comments: 11827
2923. WxLogic
Danielle is sure looking mighty healthy this AM... thx to DMAX for the extra boost.
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2922. scott39
Quoting blsealevel:


your seeing it right "W - WNW"
yes
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?
Oh yes you should ask. Quoting you from last before we both turned in for the night--You said you pay more attention to climatology, satellite pics, steering maps before buying into what the models are saying, and that do so has worked well for you for the past 3 to 4 years. I usually lurk here also because my knowledge is limited, but I've already figured out who the bsr's are and those that like to stir the pot, as opposed to providing any factual or concrete information. Please keep up the great job and all of us informed!
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10% - blob near Cape Verde
1. AN AREA OF DISTURBED WEATHER LOCATED NEAR THE WEST COAST OF AFRICA
IS ASSOCIATED WITH A TROPICAL WAVE. SOME SLOW DEVELOPMENT OF THIS
SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS IT MOVES
WESTWARD NEAR 15 MPH. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

wow Ike beat me to it...
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2918. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT MON AUG 23 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM DANIELLE...LOCATED ABOUT 850 MILES WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.

AN AREA OF DISTURBED WEATHER LOCATED NEAR THE WEST COAST OF AFRICA
IS ASSOCIATED WITH A TROPICAL WAVE. SOME SLOW DEVELOPMENT OF THIS
SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS IT MOVES
WESTWARD NEAR 15 MPH. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BERG
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting scott39:
Looks like more W than N to me.


your seeing it right "W - WNW"
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It's off to the races for me.
Have a great day everyone.
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2915. WxLogic
Good Morning...

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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?


I know a little about tropical weather. I had a good teacher. :) But for the most part my posts are usually followed by a question mark. Lol.
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Good morning everyone! I hope all had a great weekend.

Danielle looks like she is really getting stronger - even ahead of what was forecasted.

Could be a major hitting or brushing close to Bermuda.

Chance of seeing another invest later today off the African coast?
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Quoting StormW:
Looks like a heart:


Good morning, Storm. Morning, everyone. It does look like a heart. lol Nice looking storm. Best looking storm this season so far. She certainly wound up nicely since yesterday.

Hey Storm, did you lose power with those big banging storms we got yesterday?
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We've seen a lot of systems die or disappear in dry air but not this one.

CATWVLoop

Low Shear with a nice little anticyclone over it.

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Bouy at 15N 38W as of 7AM EDT. Shift in wind direction would suggest the center passed south of the bouy between 5-7AM EDT.


Member Since: September 23, 2005 Posts: 14 Comments: 11104
2908. DVG
Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?


Storm, love what you do. I know zip. I never stir re tropical systems. GW stuff has a political blend to it, and I am open, but question there.

I do investments, and was blogging there long before I came across WU. Those who like to cause trouble aren't going to answer honestly.
Here, it's all weather, and the bloggers may come or go. With investments, I come and go, depending on what I own. The names may change on the group of bloggers, but because I change forums depending on the investment, I have attained a certain laissez faire attitude re pain in the butts.

I apply that here as well.
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2907. scott39
Quoting Chicklit:
Yesterday the NHC also predicted a westerly path. This is not unexpected.
Last night at 11 p.m. Danielle was traveling at 310 degrees, this morning it's 300 degrees (WNW).
It looks unexpected on thier tropical points?
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2906. scott39
Looks like more W than N to me.
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Yesterday the NHC also predicted a westerly path. This is not unexpected.
Last night at 11 p.m. Danielle was traveling at 310 degrees, this morning it's 300 degrees (WNW).
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Ike still not working but I found it myself. Thank You very much I just want to continue bullish about the storm not hitting Bermuda.Strange I think many bloggers want a lanfall anywhere, jejejejejej
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My guess is very few know anything about tropical meteorology (including me). That is why I would like to see an "Accept" button. It would be just the opposite of the ignore button. It would allow me to create a list of bloggers whose posts I want to read. Everyone else would not be seen.

As it is now, I need to scroll thru pages and pages of posts to read yours and the posts of a few others whom I feel know what they are talking about.

Back to lurking.


Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?
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BULLETIN
TROPICAL STORM DANIELLE ADVISORY NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010
500 AM AST MON AUG 23 2010

...DANIELLE STRENGTHENS SOME MORE...

SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...14.8N 37.1W
ABOUT 850 MI...1365 KM W OF THE SOUTHERNMOST CAPE VERDE ISLANDS MAXIMUM SUSTAINED WINDS... 60 MPH... 95 KM/HR PRESENT MOVEMENT... WNW OR 300 DEGREES AT 14 MPH... 22 KM/HR MINIMUM CENTRAL PRESSURE... 997 MB...29.44 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 AM AST...0900 UTC...THE CENTER OF TROPICAL STORM DANIELLE WAS LOCATED NEAR LATITUDE 14.8 NORTH... LONGITUDE 37.1 WEST. DANIELLE IS MOVING TOWARD THE WEST-NORTHWEST NEAR 14 MPH... 22 KM/HR... AND THIS GENERAL MOTION WITH AN INCREASE IN FORWARD SPEED IS EXPECTED TO CONTINUE THROUGH TUESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 60 MPH...95 KM/HR...WITH HIGHER GUSTS.


ADDITIONAL STRENGTHENING IS FORECAST...AND DANIELLE IS LIKELY TO BECOME A HURRICANE WITHIN THE NEXT 24 HOURS. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 85 MILES...140 KM FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB...29.44 INCHES.


HAZARDS AFFECTING LAND
----------------------
NONE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 AM AST.

$$
FORECASTER KIMBERLAIN
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Storm W. I noticed the 06 GFS develops the wave behind Danielle and takes that out to sea as well. With it coming off Africa at a lower latitude and with the ridge forecasted to build back in, do you agree with this?
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2900. scott39
I wiil be glad when there is an Eye to track.
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2899. IKE
Quoting FeartheEye:


Me.. I know nothing at all about it. but i dont post but once in a blue moon and thats only if i find something that hasnt been put up yet. I typically just read what you, Ike, Patrap and others post and say... :-)


Best source to trust on tropical systems is the NHC. They might be questioned from time to time but they do a good job. And really, the questions this season about them haven't been over a "major" system. It's been over whether a TD should have been designated or an invest should have been given a 60% chance vs. a 30% chance.

The most important thing I take from reading the NHC's latest discussion isn't whether Danielle is moving at 280 degrees or 295 degrees, but that it will not hit the islands and may go east of Bermuda and be a threat to no one.

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Cotillion:
Just on an aside, Danielle already passes Bonnie on the ACE chart.

The thunderstorm I had last night passed Bonnie on the ACE chart....LOL.. :p
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?


You probably forgot more than I'll ever know about meteorology.
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?


Me.. I know nothing at all about it. but i dont post but once in a blue moon and thats only if i find something that hasnt been put up yet. I typically just read what you, Ike, Patrap and others post and say... :-)
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Just on an aside, Danielle already passes Bonnie on the ACE chart.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
2894. smuldy
Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?
i'm trying to learn and i'm trying to qualify anything i don't have a handle on (or at least don't THINK i have a handle on) by prefacing jmo or speculation; and when i'm unsure i try to ask otherwise i read what the more knowledgeable say try to grasp why they say it look at what is there and make my best guess conclusion within my limitations
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?


I'll be the first to admit I know very little. That's why I mostly lurk and pop up to ask the occasional question... :-)
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?
Good morning StormW. I think the answer to that is very few.
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Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?

THANK YOU! This is why I moslty lurk... too much bull to search through as it is...
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2890. Engine2
Quoting StormW:
I know I shouldn't, as I know everyone is entitled to their opinion on Doc's blog, but I have to ask...how many of you that come on here and just make blanket statements and like stirring the pot, REALLY know anything about tropical meteorology?

That's why I read what you post Chief and mostly ignore the rest. I like how you base your predictions upon data and experience rather than models and wishes
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2889. scott39
Doesnt the first trough have to pick up Danielle for the forecast E of Bermuda to be right?
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Looks like a hurricane to me moving almost due West, but...Meh, I don''t know.
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Crownweather and Meg and Rob Lightbrown are good people with good intentions and a good heart and over 2000 people enjoy their work.
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Quoting smuldy:
well i had started agreeing with general model guidance under the assumption that the weakness over fl picked up the storm in the midatlantic with the ridge behind it, then aw was posted suggesting it somehow skirts by that. anyone with help in how/why? if it misses that, a more sw track initially may actually matter to the long term track as a whole more than id thought 2 hours ago


On this HPC thing it looks like if it misses the first it'll have at least a wait for the second. I think?

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2883. IKE
Quoting Eugeniopr:
Ike, the link for the 6Z nogap is not working


Let me try it again....Link

Works this time.

...........................

Here's the 6Z GFS...Link
Member Since: June 9, 2005 Posts: 23 Comments: 37858
2882. Engine2
They have added model data to this site

http://moe.met.fsu.edu/tcgengifs/
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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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