TD 3 growing more organized

By: Dr. Jeff Masters , 8:01 PM GMT on July 22, 2010

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Tropical Depression Three is steadily organizing, and appears poised to become a much stronger storm than was forecast. Water vapor satellite loops show that the upper level low to the west of TD 3 that has been bringing high levels of wind shear to the storm is now moving faster to the west than predicted. This faster motion has resulted in a reduction in wind shear over TD 3, to a moderate 10 knots. Satellite images of TD 3 show that the storm is taking advantage of the lower shear by developing several low-level spiral bands to the north and east of the center. However, the center of circulation is still exposed to view, and dry air is still getting injected into the core of the storm from the southwest. The storm's heavy thunderstorms have not increased in intensity this afternoon, and the amount of heavy thunderstorm activity near the core of the storm is still limited. TD 3 will need to build more intense thunderstorms near its center before significant intensification can occur. TD 3 is a small storm, and surface observations in the Bahamas do not show the circulation very well. An outer rain band of TD 3 is now visible on Miami long-range radar, and a flood watch has been issued for all of South Florida. The Hurricane Hunters are in the storm at present, and have found top surface winds of 35 - 40 mph.


Figure 1. Afternoon satellite image of TD 3.

Track Forecast for TD 3
The storm is in a straightforward steering current environment, and TD 3 should progress steadily to the west-northwest through Sunday. This will bring the storm ashore over the Florida Keys or South Florida on Friday, and into the Gulf of Mexico on Saturday. The latest set of model runs from 8am EDT (12Z) foresee a track more to the north than the previous set of model runs. This increases the threat to the oil spill region, and I give a 40% chance that the oil spill region will see tropical storm force winds of 39 mph or higher this weekend. Oil recovery and relief well drilling operations should cease. If TD 3 makes a direct hit on the oil spill region as a tropical storm with 50 - 60 mph winds, it will likely drive a storm surge of 3 - 6 feet with high waves on top into the Louisiana marshlands, fouling a large area with oil. Oil would also penetrate into Lake Pontchartrain, which lies just two feet above sea level. However, the wave action of the storm will dilute the oil to some degree, which may limit the damage to the marshlands.

If you are wondering about the specific probabilities of receiving tropical storm force winds at your location, I recommend the wind probability product from NHC. The latest 5 pm probabilities of various locations getting tropical storm force winds, 39 mph or higher:

Marathon 55%
Marco Island 43%
Miami 34%
New Orleans 33%
Galveston 13%

Intensity Forecast for TD 3
The primary detriment to development of TD 3 for the next three days will be the presence of the large upper-level low to its west. If the low remains in its present location, relative to TD 3, it will bring wind shear of about 10 knots to the storm. This will allow for steady intensification of perhaps 20 mph per day, and TD 3 could be a hurricane by Sunday at that pace. However, if the upper-level low slows down a bit, relative to TD 3, more shear and dry air will affect the storm, potentially weakening it. None of the computer models is calling for TD 3 to strengthen into a hurricane, but if the shear continues at 10 knots, I expect TD 3 will become a hurricane. My low-confidence intensity forecast gives TD 3 a 40% chance of becoming a hurricane. NHC is putting the odds of TD 3 being a hurricane at 2 pm Sunday at 15% with their 5pm advisory.

98L
An area of disturbed weather (98L) has developed in the Gulf of Mexico's Bay of Campeche. This system is under a low amount of shear, 5 - 10 knots, and probably does not have enough time to organize into a tropical depression before making landfall along the Mexican coast a few hundred miles south of the Texas border on Friday.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next update
I'll have an update in the morning. ABC World News Tonight will probably show a sound bite I did for them today, on their 6:30pm broadcast.

Jeff Masters

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2819. WxLogic
Good morning...

Little Bonnie appears to be clinging to the little convection she has this AM.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
Morning all. Just woke up to the sound of rainfall, tropical from Bonnie. Amazing to see that most of the shower activity is practically past us already.
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Newest images looks to be tighning...she seems to be getting more compact but taking the spread out energy with her...now if an eye forms in that smaller space...she could blow up.
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2815. NoMiFL
Hello TS Misty Breeze. I hope this means lighter traffic tomorrow morning.

I've seen spit takes bigger than Bonnie.
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it totally did, thanks again

and yes there is a new blog up for those still posting in this one.
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Quoting cchsweatherman:
Tropical Storm Bonnie indeed does appear to be strengthening some tonight as satellite shows the classic appearance of a moderate tropical storm with (dare I say?) a CDO (central dense overcast) and feeder band features wrapping around the storm. Still don't think we will see significant strengthening though, although it could surprise.


LLC is still exposed to the south, that's not a CDO. If the center reforms under the convection then we might have something on our hands.
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Quoting tennisgirl08:
Cchsweatherman - what does the CDO mean?


CDO = Central Dense Overcast. Its the strongest thunderstorms that cover the center of a tropical cyclone. Sorry, couldn't resist answering.
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Quoting leelee75k:
NCHurricane you get a + and a big thank you for your explanation.


LOL, thank you, I hoped the whole explanation made sense.
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I am just going to say this. Living in New Orleans and if you have to hamper down a tropical storm or a Cat 1 Hurricane it is always good to make sure Beer is apart of you Hurricane Kit. That is what I told my wife tonight that we needed to get can goods and beer. Just thought I would give a little humor. But thanks to everyone for all of your valuable information it is much appreciated.
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CCHS: I'm a little slow. Okay, a lot slow. But are you saying that where the red was on your graphic is the center of the low??

That would be interesting.
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2807. xcool
NEWWWWWWWWWWWWWWWWWW BLOG
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Quoting CyclonicVoyage:
Squeeze play with Bonnie, is that a trough digging down in the CATL?



Yes, that is an upper trough in the central Atlantic. But, to the southwest of that trough is a massive anticyclonic upper ridge over the southeastern United States, so that upper ridge will block any effect of that trough from Bonnie. The main focus with Bonnie is the ULL to its west and the deep-layered anticyclonic ridge to its north, located over the SE US.
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Cchsweatherman - what does the CDO mean?
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Basically, the ships model must be maintaining a more westerly course for the upper level low while Bonnie goes more to the north and west for further separation. Also, the SST's will be a factor.
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Thanks for the link gator23
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2802. gator23
goodnight guys. be safe all
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2800. EricSFL
I should've known better, JFV.
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Tropical Storm Bonnie indeed does appear to be strengthening some tonight as satellite shows the classic appearance of a moderate tropical storm with (dare I say?) a CDO (central dense overcast) and feeder band features wrapping around the storm. Still don't think we will see significant strengthening though, although it could surprise.
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2798. Levi32
Quoting StSimonsIslandGAGuy:
Is Andros big enough to affect a storm? Most Bahama islands are small enough that a tropical system would hardly notice them.


In my experience all of the Bahamas including Andros usually don't have a significant adverse effect on tropical systems. A really tiny storm with a core only twice the size of that island might be affected, but it only takes all of 1-2 hours to cross the thing. Andros is also very very flat, like the everglades of Florida. Effects are pretty minimal.
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2797. hydrus
Quoting stillwaiting:
flooding event setting up for sefl,south fl,swfl and the key.....


these estimate are a bit low,also notice the area along swfl,this maybe the result of bonnie exiting near that area throwing moisture towards the coastline as it exits and maybe hugs the extreme swfl area!!!!
South Florida may have some flooding, but it will not be serious. I cant help but notice how fast this storm is moving. I realize the NHC said that rapid strengthening is not likely. I would not let my guard down for a second. Bonnie will be crossing the Gulf Stream, and it has been my experience not to trust any storm when moving over that river of steamy water. If it hits the mainland, who ever is on the north side of this thing could get whacked pretty hard. And they really wont have much warning if it does intensify rapidly coming in this fast
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2796. Patrap
pssst..


New Entry late Nighters
Member Since: July 3, 2005 Posts: 428 Comments: 129904
Quoting claire4385:
atmo, you forgot about eunice and mamou lol. The people from here are definitely cajun...Not a trace of yankee.
Not unless you consider Novia Scotia Yankee...JK ;)
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Hurrikat owes me a big apology after bashing my opinions on Bonnie.. :/
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NCHurricane you get a + and a big thank you for your explanation.
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Tampa..you had me at "getting stronger"???
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better outflow
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Question - what does NHC mean when they say a more northward component? does that mean shifting the track more eastward?

also, bonnie is so small - i think her impacts will be relatively confined and minimal. thank goodness. if this was one month later we would be in trouble.
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Quoting ElConando:


Lol he would say something like that.

Trust me... he did, I hurt myself laughing :)
Member Since: October 1, 2007 Posts: 81 Comments: 26516
Bonnie may be the smallest storm i have ever seen.

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cant wait till dmax get ur camerras out
Member Since: July 21, 2010 Posts: 0 Comments: 1181
2784. xcool
she looked better
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oh boy, 954 solto un coño! Will check back about 5.. night all. Night Orca, be good... nah!
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Quoting atmosweather:
LMAO I knew another all-caps special was coming soon...


Next one will call for a Cat 5 landfall as Pass Christian.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
Hey there everybody. Hope you are all doing well tonight. Bonnie looks to be a real rainmaker storm for sure. Buckle your seat belts for the rain, Florida. By the way after the Civil War it was designated that "Yankees" reside north of the line of Louisville, Kentucky. (Although I thought north of New Orleans, or maybe Atlanta, was good too).
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If Bonnie slips between the gap and does not go over land,I think we will have big problems on the Northern Gulf Coast.
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Bonnie sure appears to be getting stronger...really hard to say without a Visible but, it sure seem to be improving the Convection.
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Quoting hurrkat05:
IM STARTING TO SEE SOME CHANGES IN THE ULL THAT HAS BEEN AFFECTING BONNIE ALL DAY..IT HAS MOVED FURTHER AWAY AND BONNIE IS BEGINNNING TO WRAP SOME HEAVY CONVECTION AROUND HER CENTER..I WOULD NOT AT ALL BE SURPRISED TO SEE BONNIE STRENGTEN TO 60MPH WINDS BY 5AM..IF THIS TREND CONTINUES WE COULD HAVE A REAL PROBLEM ON OUR HANDS WITH BONNIE PASSING RIGHT OVER THE GULF STREAM I SURE WOULD NOT RULE OUT RAPID INTENSIFICATION..IT LOOKS TO ME BONNIE HAS WON OVER THE ULL..DR MASTERS YOU MAY BE RIGHT AFTER ALL.WITH THE SHEAR SLACKING OFF AND BONNIE HAS NO MORE OBSTACLES IN HER WAY IM STARTING TO GIVE BONNIE A 30% CHANCE OF BECOMING A STRONG CATEGORY 2 HURRICANE...IM STARTING TO ALSO ESEE ASLOW DOWN IN FORWARD MOTION TELLING ME THE ULL IS NO LONGER AFFECTING BONNIE..WE MAY HAVE A NEW WITCH IN TOWN...ALL INTERESTS ON THE LA MISS COAST SHOULD REALLY WATCH THIS CAREFULLY AND HOPE IT SHIFTS MORE EASTWARD...



like ive been saying all day u never know
however u r wishcasting abit
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Quoting StSimonsIslandGAGuy:
Is Andros big enough to affect a storm? Most Bahama islands are small enough that a tropical system would hardly notice them.
alot of andros is swamp
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2776. gator23
Quoting tropicalmommie:
I am a definite lurker. But I was just wondering if anyone knows what we can expect tomorrow in Key West?
Any info is great. Thanks!

this
Link
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Quoting Orcasystems:
It was George Lopez, the comedian.


Lol he would say something like that.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
LMAO I knew another all-caps special was coming soon...
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Quoting tropicalmommie:
I am a definite lurker. But I was just wondering if anyone knows what we can expect tomorrow in Key West?
Any info is great. Thanks!

possibly a sunny day because everything looks like its going North of you....
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As a Mississipian, I reaaly think a SOE should be issued for LA no matter the impact. The state is well below sea level. We all knew Katrina was out there, but really not projected for the area (which was MS) till the last minute (so to speak). I live 3 hours inland from NO, and I can tell you, the highways and bi-ways were traveled extensively in that time. I-55 was turned into a one-way North. We have one motel here and it was booked. We were slammed pretty good by her, power out, no grocery delivery etc...
I would rather that LA folks ere on the side of caution, than being left behind. Here where I live never thought she could reak so much havoc this far inland, but YES she did.
I watch all, and try to prepare for all; Why, cuz you never do know.
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2771. help4u
hurrkat05????????impostor????????????????
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2769. Murko
Quoting StSimonsIslandGAGuy:
Is Andros big enough to affect a storm?


Andros is mostly marsh and water, with very little elevation. The highest point is probably about 100ft.
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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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