Little change to TD 7; 93L may develop off the coast of Africa

By: Dr. Jeff Masters , 1:57 PM GMT on August 10, 2012

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Tropical Depression Seven continues westward across the central tropical Atlantic with little change in appearance. Looking remarkably like the tropical depression that became Tropical Storm Ernesto last week, TD 7 has a limited region of heavy thunderstorms, as seen on satellite loops. A large amount of dry air to the west and north is visible on water vapor satellite loops, and this dry air is interfering with TD 7's heavy thunderstorms. Wind shear is a light 5 - 10 knots, which is favorable for intensification. Ocean temperatures are 26.5°C, which is a bit on the cool side, but these temperatures are 0.5° warmer than on Thursday. Winds at the Middle Atlantic buoy 41041 peaked at 29 mph, gusting to 38 mph, at 1:50 am EDT this Friday morning, when the center of TD 7 passed about 40 miles to the south. TD 7 will pass about 60 miles south of buoy 41040 near midnight tonight. The first hurricane hunter mission into TD 7 is scheduled for Saturday morning.


Figure 1. Morning satellite image of TD 7.

Forecast for TD 7
TD 7 formed about 400 miles east-northeast of where Ernesto became a tropical depression, as seen on our wundermap. Atmospheric and oceanic conditions are currently quite similar to what Ernesto experienced, and I expect TD 7 will struggle with dry air like Ernesto did. The SHIPS model predicts that shear will remain light through tonight, then rise to the moderate range on Saturday, when the storm will encounter upper-level southwesterly winds associated with a trough of low pressure. However, ocean temperatures will warm to 28°C, which may partially counteract the increase in shear, as far as maintaining a favorable environment for development. Dry air and shear may be significant enough to destroy TD 7 on Sunday, as predicted by the GFS and ECMWF models. These models tried to kill off Ernesto in a similar situation last week, so I am inclined to believe TD 7 will survive for the coming five days, but struggle. The official NHC forecast of a 45 mph tropical storm moving through the Lesser Antilles Islands Saturday night and Sunday is a reasonable one.


Figure 2. Morning satellite image of Invest 93L.

93L
A strong tropical wave in the far Eastern Atlantic that emerged off the coast of Africa Thursday night was designated Invest 93L by NHC. In their 8 am Tropical Weather Outlook, NHC gave 93L a 50% chance of becoming a tropical depression by Sunday morning. Satellite loops show a pronounced spin to the atmosphere at mid levels, but little in the way of heavy thunderstorm activity. The latest Saharan Air Layer Analysis from the University of Wisconsin shows that while the atmosphere immediately surrounding the disturbance is moist, there is a large area of dry air from the Sahara to the west and north. This dry air will be a significant impediment to development during the coming week. The ECMWF model shows some weak development of 93L over the coming week, and predicts a general west-northwesterly track. The storm may be something Bermuda needs to be concerned about in eight or so days.

I'll have a new post this afternoon.

Jeff Masters

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Afternoon all. Currently overcast here with light showers / wind...



Not sure if this is from the ULL that was hanging about in the area or from the Twave which I thought had moved west towards the Keys....



This of Ernesto is also pretty interesting...
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Quoting TropicalAnalystwx13:

There's no reason for this to slow down in the Caribbean. It's already moving at 23 mph and may move faster after entering.

This wont survive.

I geuss we will have to wait and see
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Quoting Msdrown:


Wow thats wierd, I'll have to check that out next time. I did notice before K there wasn't any activity but I did't see them go.. I just thought they were hunkering donw in the trees.


Are you kidding. They were already in Kansas by that time.
Member Since: July 17, 2009 Posts: 69 Comments: 25345
271. 7544
the nhc talked about a watch for the LEEWARD ISLANDS are they tring to tell us that td7 could be going further north hmmmm
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I wouldn't be surprised if Ernesto becomes a Cat 3.

Member Since: July 17, 2009 Posts: 69 Comments: 25345
Quoting Grothar:
I don't know much about the ants, but it is the birds I watch. Before an approaching storm, birds will fly higher and in circles. They will repeat the pattern frequently. One can almost tell the direction the storm will approach by watching the birds leaving. Before Andrew, most birds left and headed straight North. This indicated the storm move move East to West. I knew Wilma would be much worse than forecast, because the birds flew in in NW motion and were gone the day before.


Wow thats wierd, I'll have to check that out next time. I did notice before K there wasn't any activity but I did't see them go.. I just thought they were hunkering donw in the trees.
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Quoting FtMyersgal:


Heh nc.. do you use uncooked grits? Instant grits of the long cook? Inquiring minds what to know, plus I'm allergic to fire ants and we are getting some on our property also


uncooked grits work..I use Quaker..the 5 minute version and not the instant one..as when uncooked grits hit liquid, it expands so when those critters eat it, well, they feel a bad case of indigestion..
Member Since: August 19, 2006 Posts: 13 Comments: 14439
12Z NOGAPS sends TD7 through the Leewards/ Virgin Islands and Puerto Rico.

I think a WNW turn is likely at 55W!! Believe it or not, systems did that in the past (Georges, and Jose)
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Quoting wunderkidcayman:
look I see the dry air that the NHC is talking about but look at TD7 is developing convection and it is spreading so if it spreads it will create a moisture field around it protecting it from that day air



and yes TD7 is moving fast and it was very much so expected and TD7 I am expecting TD7 to drop it forward speed near 60W



and in terms of shear yes I'm expecting it. right now it has about 5-15kt of it. I'm expecting it to increase to 20-25kts. however shear is falling in the Caribbean more so in the E and central Caribbean and I am expecting the shear to go down in the most part of the Caribbean as that ULL just N of Grand Cayman or on the Cuban coast to continue to move N taking the upper trough with it and causing shear to be light





end of part 1

There's no reason for this to slow down in the Caribbean. It's already moving at 23 mph and may move faster after entering.

This wont survive.
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Quoting LargoFl:
..oh boy..looks like a wet and interesting weekend ahead for florida huh
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Quoting wunderkidcayman:
look I see the dry air that the NHC is talking about but look at TD7 is developing convection and it is spreading so if it spreads it will create a moisture field around it protecting it from that day air



and yes TD7 is moving fast and it was very much so expected and TD7 I am expecting TD7 to drop it forward speed near 60W



and in terms of shear yes I'm expecting it. right now it has about 5-15kt of it. I'm expecting it to increase to 20-25kts. however shear is falling in the Caribbean more so in the E and central Caribbean and I am expecting the shear to go down in the most part of the Caribbean as that ULL just N of Grand Cayman or on the Cuban coast to continue to move N taking the upper trough with it and causing shear to be light





end of part 1
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12Z NOGAPS says : Leeward Islands one again.

Link
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Quoting ncstorm:


throw some grits on those fire ants..I guarantee you wont be bother by them anymore..they eat them and explode..I just didnt want to bother mine since they arent at my doorstep or trying to get in my house..


Heh nc.. do you use uncooked grits? Instant grits of the long cook? Inquiring minds what to know, plus I'm allergic to fire ants and we are getting some on our property also
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Quoting Msdrown:


Thats exactly how it works. I live on the corner of two streets. I put this stuff down with a drop spreader every 2-4 months depending on the time of year. I even put it down along both sides of the road so they don't migrate my way. I never get ants except after total floods that removes the grain and the ant mats float in. I in S MS has had the same rain you have because it has been training from the NW and W for almost a week. I'm over due right now for the treatment and still no ants. Heck with your neighbors.


I don't know how many we had here but as I was sitting on my deck watching the storm pass I saw three transfomers get hit and took out power for the entire neighborhood.
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Quoting hydrus:
92L has one mean looking low level circulation.



TD 7
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The GFS. I am trying to get it to come around to my way of thinking but it is stubborn.




Member Since: July 17, 2009 Posts: 69 Comments: 25345
look I see the dry air that the NHC is talking about but look at TD7 is developing convection and it is spreading so if it spreads it will create a moisture field around it protecting it from that day air



and yes TD7 is moving fast and it was very much so expected and TD7 I am expecting TD7 to drop it forward speed near 60W



and in terms of shear yes I'm expecting it. right now it has about 5-15kt of it. I'm expecting it to increase to 20-25kts. however shear is falling in the Caribbean more so in the E and central Caribbean and I am expecting the shear to go down in the most part of the Caribbean as that ULL just N of Grand Cayman or on the Cuban coast to continue to move N taking the upper trough with it and causing shear to be light





end of part 1
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Quoting Grothar:
..i sure hope this isnt the one going into the gulf with our high 80's to 90 degree waters
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Quoting jeffs713:
The places I can go with that statement...



Get control of your hormones and concentrate on the weather!! :)
Member Since: July 17, 2009 Posts: 69 Comments: 25345
Today in the N Leewards : breezy, hazy, and dry. Please send that SAL in hell.
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Quoting PalmBeachWeather:
Years ago my ex-hubby and me were in Ft. Lauderdale at an outside car show... He was looking a this car and I was just standing there.... After 10 minutes I looked down at my legs... They were covered with fire ants... I smacked my leg... The fire ants gave the signal. They said "GO" I made a big scene and my legs were covered with little blisters for weeks.
Any home remedies to put on the ant bites?
Member Since: October 3, 2008 Posts: 0 Comments: 5818
Quoting Grothar:


So it could go anywhere.
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Quoting hydrus:
92L has one mean looking low level circulation.
..yes sure does huh
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Quoting Grothar:


Thank you, Spock!


No. Thank you, Nyota
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Quoting LargoFl:
92L has one mean looking low level circulation.
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Quoting jeffs713:

Try something else for the fire ants. I rotate between Ortho, Spectracide, and Bayer Advanced. 3 different active ingredients. Treating them with the same thing each time is kinda like treating an infection with penicillin each time. Eventually, it will grow resistant.


Good point, but I've never had a problem after switching to Ortho. Plus I do total area application not just mounds.

Before I get warned, I'll stop with the ants.
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Here's a little known fact (Cliff Clavin style):

Messina Hof Vineyards near College Station, Texas used to and may still use fire ants instead of pesticides to kill off any insects that would otherwise feast off the grapes and vines.
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Member Since: July 17, 2009 Posts: 69 Comments: 25345
Dang, not funny apparently. I need to rethink my sense of humor...
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Quoting Grothar:


You may not be too far off.

You guys want to see some moving models?
The places I can go with that statement...
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Not a fun environment for TD 7 to pass through, that's for sure...

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Quoting ncstorm:


throw some grits on those fire ants..I guarantee you wont be bother by them anymore..they eat them and explode..I just didnt want to bother mine since they arent at my doorstep or trying to get in my house..
Years ago my ex-hubby and me were in Ft. Lauderdale at an outside car show... He was looking a this car and I was just standing there.... After 10 minutes I looked down at my legs... They were covered with fire ants... I smacked my leg... The fire ants gave the signal. They said "GO" I made a big scene and my legs were covered with little blisters for weeks.
Member Since: October 3, 2008 Posts: 0 Comments: 5818
the structure of TD7 has to improve quite a bit for watches and warnings to be issued for the islands. the systen has the classic inverted V shape of a tropical wave. all the same i expect a bit of organisation and intensification when TD7 when it approaches the area between 55deg - 60 deg west
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Quoting hurricanealley:


Fascinating!


Thank you, Spock!
Member Since: July 17, 2009 Posts: 69 Comments: 25345
Quoting Grothar:
OK, I apologize to the blog. That definitely is a BLOB




Will it spin? that is the question.
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Quoting ncstorm:


throw some grits on those fire ants..I guarantee you wont be bother by them anymore..they eat them and explode..I just didnt want to bother mine since they arent at my doorstep or trying to get in my house..

That is a waste of good grits...
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Quoting PalmBeachWeather:
I so much wanted to hear Levi's blog today. He forgot to put the mike close to him... My laptop has sucky speakers.... Any suggestions to make it louder?
I bought a cheapo amplifier with speakers at walmart,plugs into the headset output of my computer and works great.At the time it was under $50.
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236. 7544
something trying to form by andros island again maybe a small spin there
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12Z GFS blocks TD7's moisture over the NE Caribbean. Any thoughts?
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Quoting SherwoodSpirit:


I declare this blog a blob! :)


You may not be too far off.

You guys want to see some moving models?
Member Since: July 17, 2009 Posts: 69 Comments: 25345
Quoting sar2401:


That's weird part. It's been extremely dry here, and the fire ants have been eating OrthoMax like it's lunch. I've treated the yard three times since spring and they still keep coming. It think it has something to do with that end of the world thing that's supposed to happen in December. I think we'll all die from fire ant attacks. :)


Thats funny! Did you water it in after application?
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OK, I apologize to the blog. That definitely is a BLOB


Member Since: July 17, 2009 Posts: 69 Comments: 25345
TD7 will turn more WNW by 55w
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#217. Plug in some headphones, and jack up the volume?
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...TROPICAL DEPRESSION MOVING FASTER TO THE WEST...INTERESTS IN THE
WINDWARD AND LEEWARD ISLANDS SHOULD MONITOR THE PROGRESS THIS
SYSTEM..

Yesterday, the Leewards WERE NOT MENTIONED

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Quoting Grothar:


I know, these bloggers are throwing around the word blob without understanding the full science behind it. I declared 93L a blog 4 hours before they named it.

I declared TD 7 a blog 7 hours before they named it.

The correct terminology for what it off of Florida and in the Caribbean is called a "mess".


I declare this blog a blob! :)
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is there anyone from the Northeast on here ?..some really bad weather up there now huh................................SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ALBANY NY
1142 AM EDT FRI AUG 10 2012

NYZ060-061-101630-
WESTERN COLUMBIA NY-EASTERN COLUMBIA NY-
1142 AM EDT FRI AUG 10 2012

...A STRONG THUNDERSTORM IN

COLUMBIA COUNTY IN EAST CENTRAL NEW YORK...

AT 1137 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
THUNDERSTORM CAPABLE OF PRODUCING...WINDS AROUND 40 MPH...FREQUENT
LIGHTNING...AND HEAVY RAIN. THIS STORM WAS LOCATED NEAR ANCRAM...OR
ABOUT 14 MILES NORTHEAST OF RHINEBECK...AND MOVING NORTH AT 15 MPH.

RAINFALL RATES OF GREATER THAN ONE HALF INCH PER HOUR IS LIKELY WITH
THIS STORM. THIS WILL RESULT IN PONDING OF WATER ON ROADS AND OTHER
POOR DRAINAGE LOCATIONS.

THE THUNDERSTORM WILL BE NEAR...
CLAVERACK BY 1220 PM EDT
PHILMONT BY 1230 PM EDT

LAT...LON 4227 7374 4230 7346 4200 7360 4203 7376
TIME...MOT...LOC 1542Z 193DEG 14KT 4205 7368

$$

JPV
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Quoting ncstorm:
there is a surface low trying to form off of florida

..looks like its going to be an Interesting weekend for sure,hope it does not get too bad here,local weather guys say 50% rain chances..that might change
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I don't know much about the ants, but it is the birds I watch. Before an approaching storm, birds will fly higher and in circles. They will repeat the pattern frequently. One can almost tell the direction the storm will approach by watching the birds leaving. Before Andrew, most birds left and headed straight North. This indicated the storm move move East to West. I knew Wilma would be much worse than forecast, because the birds flew in in NW motion and were gone the day before.
Member Since: July 17, 2009 Posts: 69 Comments: 25345

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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.