Tropical Depression Seven forms

By: Dr. Jeff Masters , 2:25 PM GMT on August 14, 2011

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The latest in our unusual number of weak tropical cyclones this season, Tropical Depression Seven, has formed to the southeast of Bermuda. Unless you live in Bermuda, TD 7 is not going to be a concern. Radar out of Bermuda shows an area of rain on the northern side of TD 7 beginning to approach the island, and rain from the storm will likely affect the island tonight and on Monday. TD 7 is not well-organized, and has only limited heavy thunderstorms, as seen on visible satellite images. While wind shear is a low 5 - 10 knots, dry air surrounds TD 7, and is keeping the storm from intensifying. None of the computer models foresee that TD 7 will ever become more than a weak tropical storm.


Figure 1. Morning satellite image of TD 7.

92L
TD 7 isn't the only system Bermuda needs to watch, Invest 92L is a day behind it, and will follow a path very similar to TD 7's. The disturbance will pass close to Bermuda on Tuesday, bringing the island a second round of tropical rains. However, Invest 92L is very disorganized, as seen on recent visible satellite loops. Dry air and close proximity to TD 7 will likely keep 92L from showing significant development over the next two days, with NHC giving the system just a 30% chance of developing into a tropical depression by Tuesday morning.

Elsewhere in the tropics
The disturbance midway between the Lesser Antilles Islands and the coast of Africa we've been tracking over the past few days, Invest 93L, has fallen apart and is no longer a threat to develop. This system will need to be watched once it enters the Caribbean later this week, though. None of the reliable models for predicting tropical cyclone formation predict development of this system or any new disturbances over the coming week.

Jeff Masters

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Quoting angiest:
As promised, photos from Lake Somerville earlier today.  The lake is at or below 50% capacity.
That is a pretty large lake, sad that the drought is doing this :(
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Quoting scott39:
Hey...Thats Billy Joel!


Nope Rod Stewart with his hair dyed!
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Good Evening Folks. The latest in our unusual number of weak tropical cyclones this season, Tropical Depression Seven, has formed to the southeast of Bermuda.

Still waiting for the first hurricane of the season (with the Avg. formation date being around Aug 10th I believe) but this is quite the anomaly this year.

With all of the trof and frontal remnants to come over the next few weeks, does anyone think our first Cane might come from closer to the US or Caribbean rather than from a CV wave? Just a thought but anything could happen; the same way we have had a cluster of CV tropical storms recently, this pattern could change in later August and we could have (the usual) cluster of Hurricanes.....I don't have a clue what will happen.
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1272. angiest
As promised, photos from Lake Somerville earlier today.  The lake is at or below 50% capacity.
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1271. scott39
Quoting GTcooliebai:

Like this :)

Hey...Thats Billy Joel!
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Quoting GTcooliebai:

Like this :)

1977? Leisure suit gave it away.lol
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1269. pottery
Quoting ShenValleyFlyFish:
No you're wrong! The chronalflaug adveconium heliologica vorticon motion will mitigate for that.

I stand incorrected......

:):))
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Quoting weatherjr:
Our EX-Invest 93 finally POOF. What will be next? (for eastern most the caribbean)



Without betting my house away......but, I belive 93L will at least get an Invest Status again to monitor once it passes the Eastern Caribbean.
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Quoting daddyjames:



It was. I was in the first grade at the time. We went to school and immediately allowed outside for recess to try to catch the showflakes on our tongues. If I remeber correctly portions of Miami actaully had accumulations of ~1 inch on the cars. Of course anything that hit the ground melted immediately.

Like this :)

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Quoting scott39:
If it does develope by 75W, do you see it being pulled N into the GOM? TIA


Based upon the forecast steering for next Wednesday and Thursday a weak to moderate TS would be steered to the WNW across the NW Caribbean. There is a weakness forecasted between the Bahamas and Louisiana around Wednesday that could pull a system to the NW but it would all be a matter of timing. Come Thursday a high is shown digging down from Texas that could shunt it WNW across the Yucatan or serve as a blocker forcing a more NW track.

That is the best I can say right now.All a matter of timing, strength and, of course, something forming in the first place
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Quoting pottery:

I have been saying that for days.....
No you're wrong! The chronalflaug adveconium heliologica vorticon motion will mitigate for that.
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Week 2

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1260. pottery
Quoting TampaSpin:



Hey Pot......that makes at least 2 of us correct.......LOL.....been on Vacation since August 1st and just got back Friday....glad things have been quite for most in the Tropical Regions thus far.

Hope Taz does not see that sentence, LOL!

A 2 week Holiday is a Good Thing! Hope the weather was good too!
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Quoting scott39:
ex93L not developing before now is not a good thing, unless it runs itself into CA as rain.



Huh?
Member Since: September 2, 2006 Posts: 110 Comments: 6814
Quoting GTcooliebai:
That would've been quite the site, wish I was alive then, we almost had snow last year.



It was. I was in the first grade at the time. We went to school and immediately allowed outside for recess to try to catch the showflakes on our tongues. If I remeber correctly portions of Miami actaully had accumulations of ~1 inch on the cars. Of course anything that hit the ground melted immediately.
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Quoting scott39:
ex93L not developing before now is not a good thing, unless it runs itself into CA as rain.
That could very well happen, unless a trough swings down & tries to pull it up.
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Quoting GTcooliebai:
Thanks for your fine explanation on shear & what each numerical value inside the yellow shapes represents, along with the tan color streamlines in the background.


welcome; but i got that off their site most folks dont read the instruction manuel :)
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Quoting pottery:

I have been saying that for days.....



Hey Pot......that makes at least 2 of us correct.......LOL.....been on Vacation since August 1st and just got back Friday....glad things have been quite for most in the Tropical Regions thus far.
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1254. scott39
ex93L not developing before now is not a good thing, unless it runs itself into CA as rain.
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Quoting daddyjames:


Actually, it was 1977. I was there. Remeber walking out of the house thinking "What is this white stuff falling out of the sky?"

From Wikipedia:
January 17, 1977: The pressure gradient between a strong ridge over the Mississippi Valley and a Nor'easter over Atlantic Canada sends very cold temperatures southward into the state. Areas around Pensacola are the first to receive the snow. Then the rest of The Panhandle. Followed by record accumulations for The Nature Coast, the I-4 corridor (both Orlando and Tampa receive light accumulations of about 1-2" with a few isolated spots reportedly receiving 3-6"), and finally South Florida. By early on January 19, West Palm Beach reported snow for the first time on record, with snow flurries reaching as far south as Homestead. The snow causes little impact as it was of the dry variety, though the accompanying cold air results in hundreds of millions of dollars in damage (Orlando tied the 1899 record of over six consecutive nights well-below freezing). On January 20, the Miami Herald reports the event as the front page story, with a headline of a size usually reserved for the declaration of war.

http://en.wikipedia.org/wiki/List_of_snow_events_ in_Florida#cite_note-almanac-11
That would've been quite the site, wish I was alive then, we almost had snow last year.
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1252. pottery
Quoting TampaSpin:




The very dry air is what is preventing it from forming!!!!!






I have been saying that for days.....
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Quoting kmanislander:


On the one hand it may but on the other..... well perhaps.


May it perhaps not develop then also.......Hey Brother.....Lets keep our fingers crossed for little to nothing this year!
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Quoting TampaSpin:



Stop giving us all that smooth Lawyer talk......is the dang thing gonna develop or not.......LOL


On the one hand it may but on the other..... well perhaps.
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Quoting kmanislander:


Good evening.

Eastern Caribbean to 63W is the historical cut off point for development of waves that have not been classified as a TD before passing 60W. After that it tends not to happen until 75 or 80W. I reviewed about 30 years of data once to reach that conclusion. There have been about 8 systems to become classified between 63 and 75W in the past 30 yrs approx. They are the anomalies.



Stop giving us all that smooth Lawyer talk......is the dang thing gonna develop or not.......LOL
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Quoting TampaSpin:



Thelm i too see some very troubling signs coming for the Bahamas and the Eastern Seaboard. I just don't like what is happening already.


Hey, I resemble that remark!
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Quoting Tropicsweatherpr:
96L is now Ex96L.

BEGIN
NHC_ATCF
invest_DELETE_al962011.ren
FSTDA
R
U
040
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0000
201108142019
NONE
NOTIFY=ATRP
END


That was fast.
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Quoting jaxbeachbum:
I remember reading, and I don't know the year, in the 70's I believe, that there were flurries in Miami but the interesting part is that it got cold enough that the iguanas were falling out of trees.




Actually, it was 1977. I was there. Remeber walking out of the house thinking "What is this white stuff falling out of the sky?"

From Wikipedia:
January 17, 1977: The pressure gradient between a strong ridge over the Mississippi Valley and a Nor'easter over Atlantic Canada sends very cold temperatures southward into the state. Areas around Pensacola are the first to receive the snow. Then the rest of The Panhandle. Followed by record accumulations for The Nature Coast, the I-4 corridor (both Orlando and Tampa receive light accumulations of about 1-2" with a few isolated spots reportedly receiving 3-6"), and finally South Florida. By early on January 19, West Palm Beach reported snow for the first time on record, with snow flurries reaching as far south as Homestead. The snow causes little impact as it was of the dry variety, though the accompanying cold air results in hundreds of millions of dollars in damage (Orlando tied the 1899 record of over six consecutive nights well-below freezing). On January 20, the Miami Herald reports the event as the front page story, with a headline of a size usually reserved for the declaration of war.

http://en.wikipedia.org/wiki/List_of_snow_events_ in_Florida#cite_note-almanac-11
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1245. scott39
Quoting kmanislander:


Same as before. First see what it does near 55W, which is close to where the wave axis is now, and after that watch for it once it gets to 75W. You may recall from my posts on 93L that I was never a believer in it doing much of anything all the way to the islands so no surprise there.

Waves tend to slow just below Haiti and it may start to do something in that general area.
If it does develope by 75W, do you see it being pulled N into the GOM? TIA
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Quoting thelmores:


Ah yes...... as you could tell, I failed 1st grade art class, so I was always trying to get better with my squiggly lines!


lol...maybe true but I liked em
Member Since: August 23, 2006 Posts: 0 Comments: 678
96L is now Ex96L.

BEGIN
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invest_DELETE_al962011.ren
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END

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Quoting scott39:
Thats interesting, So what is your thoughts on ex93L?


Same as before. First see what it does near 55W, which is close to where the wave axis is now, and after that watch for it once it gets to 75W. You may recall from my posts on 93L that I was never a believer in it doing much of anything all the way to the islands so no surprise there.

Waves tend to slow just below Haiti and it may start to do something in that general area.
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Quoting blsealevel:
CIMSS

Atmospheric Motion Vector (AMV) Gridded Analysis

Analyses are calculated utilizing gridded output from the auto editing process of the satellite atmospheric motion vector (AMV) fields. The AMV data are fit to a one degree grid at the following heights (100, 150, 200, 250, 300, 350, 400, 500, 600, 700, 775, 850, and 925 hPa), with data sparse regions at each height filled with numerical model output. Grids consist of u and v wind components.

The background model used is usually the United States Navy's NOGAPS, but NOAA's GFS model serves as a back up.

Using the gridded atmospheric motion vector output u and v AMV components are averaged over an upper layer (150, 200, 250, 300, and 350 hPa) and a lower layer (700, 775, 850, and 925 hPa). The difference in these averaged components is used to compute the speed shear between the upper and lower layers. The contours show the vector magnitude shear (absolute value). The streamlines indicate the direction of the shear.


Thanks for your fine explanation on shear & what each numerical value inside the yellow shapes represents, along with the tan color streamlines in the background.
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Quoting brazocane:


Miss your drawings highlighting the structure of a system


Ah yes...... as you could tell, I failed 1st grade art class, so I was always trying to get better with my squiggly lines!
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Quoting thelmores:


Likewise Baha...... I consider you Sir as one of fine individuals I mentioned earlier......

I am always lurking, and hope to have more time to Blog...... The Atlantic Hurricane season always brings me out of my shell.....

At peak times however, the blog moves so fast its hard to even keep up, must less participate.

I worry about you and your neighbors this year my friend..... the way the High is setting up further west, I believe your risk is higher this year than any recent year...... stay safe my friend! ;)


Wow, where have you been. I miss your circles :-)
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1238. scott39
Quoting kmanislander:


Good evening.

Eastern Caribbean to 63W is the historical cut off point for development of waves that have not been classified as a TD before passing 60W. After that it tends not to happen until 75 or 80W. I reviewed about 30 years of data once to reach that conclusion. There have been about 8 systems to become classified between 63 and 75W in the past 30 yrs approx. They are the anomalies.
Thats interesting, So what is your thoughts on ex93L?
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1237. Mucinex
Quoting klew136:

The iguanas falling out of trees happened two years also, in the Keys, we didn't go over 55 for a period of at least four weeks, and the lows were in the 40's and no one has heat in their house. We weren't upset over the iguanas because they are not suppose to live here, but we were upset over the fish kill due to cold temps on the surface and no oxygen to the fish.

Yeah our iguanas died too. We were upset because it killed the 2 big neighborhood iguanas, El Jefe and El Capitan. They were both over 6 feet and had been around forever. Now we've got basilisks and bahamian curl tails.
And as always there is a season for everything. We had a ton of dead baby turtles cooked in the road today from the heat.
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1236. Patrap

Live as if you were to die tomorrow. Learn as if you were to live forever.

Mohandas Gandhi

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Quoting thelmores:


Likewise Baha...... I consider you Sir as one of fine individuals I mentioned earlier......

I am always lurking, and hope to have more time to Blog...... The Atlantic Hurricane season always brings me out of my shell.....

At peak times however, the blog moves so fast its hard to even keep up, must less participate.

I worry about you and your neighbors this year my friend..... the way the High is setting up further west, I believe your risk is higher this year than any recent year...... stay safe my friend! ;)



Thelm i too see some very troubling signs coming for the Bahamas and the Eastern Seaboard. I just don't like what is happening already.
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Quoting scott39:
So Eastern Caribbean...dead!! Central/Western...watch it!!


Good evening.

Eastern Caribbean to 63W is the historical cut off point for development of waves that have not been classified as a TD before passing 60W. After that it tends not to happen until 75 or 80W. I reviewed about 30 years of data once to reach that conclusion. There have been about 8 systems to become classified between 63 and 75W in the past 30 yrs approx. They are the anomalies.
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1233. scott39
Quoting AtHomeInTX:
Might need to watch that front in the gulf and 93l in a few days.

With the MJO coming back in the picture, is what makes me think 93L will develope. Not to mention hot water water for energy and low wind shear for a favorable enviroment.
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Quoting BahaHurican:
Good to see you thel.... hope u have time to swing through here a little more regular this season.


Likewise Baha...... I consider you Sir as one of fine individuals I mentioned earlier......

I am always lurking, and hope to have more time to Blog...... The Atlantic Hurricane season always brings me out of my shell.....

At peak times however, the blog moves so fast its hard to even keep up, must less participate.

I worry about you and your neighbors this year my friend..... the way the High is setting up further west, I believe your risk is higher this year than any recent year...... stay safe my friend! ;)
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Quoting scott39:
So Eastern Caribbean...dead!! Central/Western...watch it!!



Yep......even if it looks completely dead the wave axis will still be there. Just need to watch and see as some models are showing the possibility yet.
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Might need to watch that front in the gulf and 93l in a few days.

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And the wave following the one about to exit Africa looks HUGE...But until she exits and shows she can sustain no biggie...
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1227. klew136
Quoting NHCaddict:


Definitely flurries in Miami in the mid/late 70s. My husband was in college there at the time.


The iguanas falling out of trees happened two years also, in the Keys, we didn't go over 55 for a period of at least four weeks, and the lows were in the 40's and no one has heat in their house. We weren't upset over the iguanas because they are not suppose to live here, but we were upset over the fish kill due to cold temps on the surface and no oxygen to the fish.
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Quoting jaxbeachbum:


You're right, no iguanas back in 70's. It was last year and it would have been a perfect time to gather up a large population and take them back to their rightful place.

My last white Christmas was in 1985, Kentucky. We moved to Florida summer of 1986.


As best as I can recall, Iguanas have been a problem around PBIA for at least 15 years, if not more. But you are probably right, not WAY back to the 70's.
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Quoting weatherh98:


Hot hot hot hot there will be storms


Member Since: September 10, 2007 Posts: 0 Comments: 10577

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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.