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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850mb and 700mb Vorticity are excellent...500mb is pretty good..but i think the 200mb vorticity is hurting it.
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2330. xcool
center eastern of that convective
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Per ADT..
Scene Type : IRREGULAR CDO
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2328. KEEPEROFTHEGATE (Mod)
06L/TS/D/CX
MARK
14.48N/37.28W

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Quoting atmoaggie:
The only severe wind reports in LA are in N LA. Many of them recent...



i guess they didn't put them up yet?? but it was definitely significant. it was the same eery howl i remember from andrew, lili, and gustav. it lasted for only 10 minutes, though
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2325. will45
Quoting smuldy:
if her outflow gets strong enough she will strengthen the ridge and there may be no weakness at least initially


may be no weakness is the key tho. timing will be the thing with this setup
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2324. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting PcolaDan:


I did mean huge as in "good huge", away. Also puts them away from the bigger swells, the weak side if it gets too close.
Ah. Correct!
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Quoting RobbieLSU:


Not sure about the mid-Atlantic, but they have a small population in the Gulf!
Hey, there Robbie.

Looks like Danielle will ride the edge of the good stuff:
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Alrighty then.. Whom thinks we will see an eye as early as monday.. Or u think later and y?
Member Since: August 15, 2008 Posts: 0 Comments: 2133
Quoting atmoaggie:
Actually, the very last one puts a little more curve into the end, away from Bermuda, to the east, if looking at the middle of the cone, only. (bad idea!)


I did mean huge as in "good huge", away. Also puts them away from the bigger swells, the weak side if it gets too close.
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I am sure that gustfront will die before reaching lafayette..as usual...i hope i just made the weather mad..i see lightning wayyy in the distance lol
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nite all. have a good monday.
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The only severe wind reports in LA are in N LA. Many of them recent...

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2315. smuldy
Quoting will45:


yes but if she is stacked vertically she gonna feel the weakness sooner
if her outflow gets strong enough she will strengthen the ridge and there may be no weakness at least initially
Member Since: July 23, 2010 Posts: 0 Comments: 527
Quoting atmoaggie:
Are there orcas is the middle Atlantic?


Not sure about the mid-Atlantic, but they have a small population in the Gulf!
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Who was it wagering that Danielle would cross 15 N west of 50 W? Well, we're doing it, and east of 40 W, even.

So, in lieu of "fish" storm, I'll call it an "Orca" storm. Are there orcas in the middle Atlantic?
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2312. smuldy
Quoting errantlythought:


An Anticyclone has nothing to do with the movement of a TC, directly. You could argue that its capability for increasing deepening would produce more poleward movement, but that's a tad bit of a stretch in logic. She's still sitting under that ridge, regardless.
And if she grows enough, that ridge will too.
Member Since: July 23, 2010 Posts: 0 Comments: 527
I'am not beliving what the models say at this moment in time.Maybe in another three days when it is closer to land where the hurricane hunters can fly in it,and give us real data.
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Quoting CyclonicVoyage:
Little bit about gust fronts.


funny. i left to google the term and ended up on wiki reading about them and came back to find your post.

interesting. definitely learned something new.
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2309. will45
Quoting errantlythought:


An Anticyclone has nothing to do with the movement of a TC, directly. You could argue that its capability for increasing deepening would produce more poleward movement, but that's a tad bit of a stretch in logic. She's still sitting under that ridge, regardless.


yes but if she is stacked vertically she gonna feel the weakness sooner
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Im out yall, Hurricane status tomorrow morning is very likely in my opinion good night.
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2307. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting will45:


when that anticyclone gets dead center over her the northwest will start


An Anticyclone has nothing to do with the movement of a TC, directly. You could argue that its capability for increasing deepening would produce more poleward movement, but that's a tad bit of a stretch in logic. She's still sitting under that ridge, regardless.
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Quoting PcolaDan:


Unless you live in Bermuda. Then that last one is huge. ;)
Actually, the very last one puts a little more curve into the end, away from Bermuda, to the east, if looking at the middle of the cone, only. (bad idea!)
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Quoting ChrisDcat5Storm:
the stronger the storm the more west movement?


Not necessarily. A weaker storm will tend to be pushed around by primarily low-level steering currents, while a stronger storm will be guided by the average of all the steering currents acting upon it at every level.

Make sense?
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Little bit about gust fronts.
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Quoting Hurricanes101:


the circulation is very strong, a relocation is unlikely at this stage


Originally, Danielle had an elongated circulation. It does seem to be building around the 11:00 position. However, it may fluctuate according to the broadness of the circulation.
Member Since: September 30, 2005 Posts: 0 Comments: 1606
Quoting ho77yw00d:
goodnight everyone cant wait until morning to see Danielle lol :) nite


Why?
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Quoting 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.




I totaly agree here. Believe me, I will definetly watch this storm and every other storm that forms in the Atlantic. I think we get use to the models and forget the fact that theres a lot to play here. Time has to be right, in order for the troughs to steer Danielle out to sea. What if Danielle slows down or stalls. What if Danielle changes track. A lot of People are going to be in danger. Seeing that Danielle if forecasted to strengthen with time.jmo.
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Member Since: August 15, 2008 Posts: 0 Comments: 2133
2298. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting truecajun:


ah. yes. here is the rain. that wind was unnerving. i didn't like it catching me by surprise like that.


Gust fronts can produce nasty straight line winds of CAT 2 strength. Dry line between the gust front and the storm complex is why you weren't seeing any rain.
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Quoting atmoaggie:
No great big changes here...



Unless you live in Bermuda. Then that last one is huge. ;)
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Quoting PcolaDan:


Was quite easy to figure out Baton Rouge, considering your handle is "truecajun". DOH!

Not seeing any warnings nor watches for your area. Should be over pretty soon.


thanks.
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2294. Seastep
Danielle is at ~14N/37W.

Check the nice outflow to the E of that.
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2293. JLPR2
Quoting cirrocumulus:
It seems the center of Danielle may relocate to the southeast. It is still in the early stages.


I'm thinking more of the mid level circulation dragging the LLC under it.
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2292. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting truecajun:


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.


Was quite easy to figure out Baton Rouge, considering your handle is "truecajun". DOH!

Not seeing any warnings nor watches for your area. Should be over pretty soon.
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2290. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #8
TROPICAL STORM MINDULLE (T1005)
12:00 PM JST August 23 2010
===============================

SUBJECT: Category One Typhoon In South China Sea

At 3:00 AM UTC, Tropical Storm Mindulle (994 hPa) located at 16.1N 110.5E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The storm is reported as moving west at 12 knots

Dvorak Intensity:

Gale Force Winds
=================
150 NM from the center

Forecast and Intensity
=======================
24 HRS: 18.1N 107.1E - 45 knots (CAT 1/Tropical Storm)
45 HRS: 19.8N 105.4E - 45 knots (CAT 1/Tropical Storm)
69 HRS: 21.0N 103.0E - 30 knots (Tropical Depression)
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Quoting LADobeLady:
where are you? the howling finally stopped here. i'm in brusly (west baton rouge)


I'm in Houma, it's storming here.


ah. yes. here is the rain. that wind was unnerving. i didn't like it catching me by surprise like that.
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2288. will45
Quoting errantlythought:


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.


when that anticyclone gets dead center over her the northwest will start
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Quoting atmoaggie:


Aggie I love it when you post that, it really shows how much (or little) the forecast track changes, thanks!
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Quoting truecajun:


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


Actually looks like 2 gust fronts developed.
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Here's some images..
Member Since: August 15, 2008 Posts: 0 Comments: 2133
Btw, Koritheman's done a really nice blog on Danielle tonight. Really, good night!
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No great big changes here...

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the stronger the storm the more west movement?
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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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