Bonnie weakens to a tropical depression

By: Dr. Jeff Masters , 8:40 PM GMT on July 23, 2010

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Tropical Depression Bonnie is nearing the end of its traverse of South Florida, and passage over land has significantly disrupted the small storm. Satellite images show almost no heavy thunderstorms near Bonnie's center of circulation, and the center is now exposed to view. Radar-estimated rainfall from the Key West radar shows that Bonnie dumped very little rain on South Florida--maximum rainfall amounts from the storm were about four inches over a small region southwest of Miami. Water vapor satellite loops show that Bonnie is embedded in a large area of dry air, thanks to an upper level low to the west over the Gulf of Mexico. This low has brought an increasing amount of wind shear to Bonnie today, and shear has increased from 20 knots this morning to 25 knots this afternoon. Surface observations in South Florida currently don't show any tropical storm force winds. Bonnie's top winds today were at Fowey Rocks, which had sustained winds of 46 mph, gusting to 53 mph, at 10:45 am EDT.


Figure 1. Satellite image of Bonnie from NASA's MODIS instrument, taken at 17:10 UTC July 23, 2010. Image credit: NASA/.

Track Forecast for Bonnie
The latest set of model runs from 8am EDT (12Z) are very similar to the three previous sets of runs, and this degree of consistency gives me confidence that Bonnie will stay within the cone of uncertainty depicted on the track forecast images. The projected track will take Bonnie over the oil spill region, and the storm's strong east to southeasterly winds will begin to affect the oil slick on Saturday morning. Assuming Bonnie doesn't dissipate over the next day, the storm's winds, coupled with a likely storm surge of 2 - 4 feet, will drive oil into a substantial area of the Louisiana marshlands. However, the current NHC forecast has Bonnie making landfall in Louisiana near 9pm CDT Saturday night. According to the latest tide information, this will be near the time of low tide. This will result in much less oil entering the Louisiana marshlands than occurred during Hurricane Alex in June. That storm brought a storm surge of 2 - 4 feet and sustained winds of 20 - 30 mph that lasted for several days, including several high tide cycles. The latest oil trajectory forecasts from NOAA (Figure 2) predicts potential oil impacts along a 150-mile stretch of Louisiana coast on Sunday.


Figure 2. Oil Trajectory forecast for Sunday for the Deepwater Horizon oil spill. Image credit: NOAA.

Intensity Forecast for Bonnie
Bonnie has been disrupted by its passage over land, and it will take at least six hours for the storm to reorganize once it moves over the warm waters of the Gulf of Mexico tonight. This process will be hindered by the large upper-level low to its west. If the low remains in its present location, relative to Bonnie, it will bring high wind shear of about 20 - 30 knots to the storm. This will allow for only slow intensification, or may even destroy Bonnie. Bonnie is unlikely to intensify to more than a 50 mph tropical storm, and I give a 30% chance it will dissipate over the Gulf of Mexico before making landfall. The GFDL model predicts Bonnie could hit the Gulf Coast as a 50 mph tropical storm, but the other major models such as the HWRF, GFS, ECMWF, and NOGAPS show a much weaker storm. I don't give Bonnie any chance of becoming a hurricane. NHC is putting the odds of Bonnie being a hurricane at 2 pm Saturday at 4% (5pm advisory.)

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 probabilities of various locations getting tropical storm force winds, 39 mph or higher, from the 5pm EDT advisory:

Buras, LA 30%
New Orleans 28%
Mobile, AL 37%
Pensacola, FL 30%

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 Saturday morning.

Jeff Masters

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But it was all part and parcel of a "group-think" that felt Big Oil should be able to do pretty much what it wanted.

If Big Oil could do whatever it wanted, it would drilling in the middle of nowhere Alaska instead of being forced out into the middle of the gulf. A spill in Alaska would only affect a few caribou, rather than millions of people's livelihoods.
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910. mobal
Hand Crank Starters....RUNNING!

Quoting StormW:


Yep.

Do ya remember, no seatbelts?
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Quoting Patrap:
The Mayans are not Happy with BP atall.

Were DOOMED

My wife is of Mayan ancestry, just click on my new avatar, true but the Mayans were supersmart!

pat you're a good man though , hope all well goes well in NOLA, even though Bonnie might appear like a small insignificant system, it can reek havoc.
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Quoting StormW:


Yep.

Do ya remember, no seatbelts?


I remeber no seat belts and the switch under the dash for the reserve gas tank!
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Quoting atmosweather:


And look at them turning back around immediately and trying to find them anywhere they can.

Yep, Bonnie likely to be downgraded at 11 P.M if no west winds are found.
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Quoting BahaHurican:
But that's the beauty... there they are, nattering away, and u can't hear a thing.... BWAhahahaha.....

LOL


And they're having to read through every post, while we just breeze through.

Kinda like using the "20 posts or less" line at a grocery store...
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Quoting cloudy0day:


The vent window was the air conditioner on my first car, lol.


my first had a pushbutton on the dash, '65, now they're coming back.
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They must have flown right over the west winds, the west winds was probably in a very short distance around 100 yards lol Just Joking, Hey you never know, If that's the case this system may be dead.
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Quoting StormW:


Broadcaster!

Just had ta!
Tāʾ is the 16th letter of the Arabic alphabet...Tāʾ-caster! LOL.
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Look, lets face reality....... look at all the dry air...... look at the 25mph shear, look at the position of Bonnie in relation to the ULL.....

I know some of you have established a relationship with Bonnie, and her existence...... but let me explain..... Bonnie is still breathing....... but she is brain dead! Bonnie will never exist as you remembered her! LOL

Sorry for the poor analogy...... but I was trying to evoke an emotional response...... Bonnie is for all practical purposes history......
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Quoting BahaHurican:
That's that gossipy kinda "they say". ur not supposed to ask for specifics, atmowx...


I hate gossip!...LOL!
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting StormW:


OMG!

Forgot about dem!
3 speed column shift...of course.
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Quoting MiamiHurricanes09:
Very broad area of low pressure; no west wind reports.



And look at them turning back around immediately and trying to find them anywhere they can.

Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting Patrap:
The Mayans are not Happy with BP atall.

Were DOOMED

My wife is of Mayan ancestry, just click on my new avatar, true but the Mayans were supersmart!
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That's that gossipy kinda "they say". ur not supposed to ask for specifics, atmowx...
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Quoting atmosweather:
012830 2621N 08301W 9250 00776 0103 +220 //// 107009 010 019 000 01

Well there's the center...no W winds.
It's very broad, notice the large amount of 1010.3-1010.9mb readings.
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Quoting F4PHANTOM:
Youngsters don't know what your talking about


The vent window was the air conditioner on my first car, lol.
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Quoting navarch:


Usually just a lurker, but I'll break my silence on this one. My wife is an English teacher at this school. Lots of good kids here that are very active in the community. Quite refreshing.


With a Son in Jesuit here and Dau, Dominican Graduate,,I can concur 100%
Member Since: July 3, 2005 Posts: 426 Comments: 128648
Very broad area of low pressure; no west wind reports.

AF305 0603A BONNIE HDOB 25 20100724
012530 2615N 08304W 9244 00799 0121 +228 //// 049008 009 023 001 01
012600 2616N 08304W 9249 00794 0120 +228 +228 051008 009 022 000 00
012630 2618N 08304W 9254 00784 0114 +226 //// 053012 014 022 001 01
012700 2619N 08304W 9249 00785 0108 +227 //// 053015 015 020 000 01
012730 2621N 08304W 9251 00777 0106 +224 //// 062015 017 /// /// 05
012800 2621N 08303W 9244 00784 0104 +222 //// 080010 012 018 001 05
012830 2621N 08301W 9250 00776 0103 +220 //// 107009 010 019 000 01
012900 2621N 08259W 9249 00779 0103 +222 //// 126014 017 020 000 01
012930 2621N 08258W 9249 00779 0105 +220 //// 135021 023 025 000 01
013000 2621N 08256W 9249 00780 0106 +224 //// 137027 030 027 000 01
013030 2621N 08254W 9248 00782 0107 +226 +221 141031 032 028 000 03
013100 2621N 08253W 9246 00784 0106 +225 +219 144029 031 /// /// 03
013130 2619N 08253W 9250 00782 0107 +226 +222 149026 026 029 002 00
013200 2618N 08253W 9248 00784 0107 +230 +222 156024 026 027 000 00
013230 2617N 08253W 9249 00784 0107 +230 +219 159022 023 027 000 00
013300 2615N 08253W 9248 00785 0109 +227 +223 160019 020 024 000 03
013330 2614N 08254W 9243 00790 0108 +231 +218 167016 018 018 000 03
013400 2613N 08256W 9253 00780 0107 +233 +221 184012 013 017 000 03
013430 2613N 08258W 9247 00785 0107 +229 +224 187010 010 016 000 00
013500 2613N 08259W 9250 00781 0107 +228 +228 179008 009 016 000 03
$$
;
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012830 2621N 08301W 9250 00776 0103 +220 //// 107009 010 019 000 01

Well there's the center...no W winds.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting nolacane2009:
I have a question for whoever would like to answer. Who thinks that this year will produce as many hurricanes or tropical storms as they say this year?


If dey cant tell me when where and How big, Den I could care less about the Numbers they jockey around like Bantha Fodder.

If they spent 1 tenth of that input to preparation and Education ..it would serve the Public 100 times over.

For the better,
Member Since: July 3, 2005 Posts: 426 Comments: 128648
Quoting zebralove:
Just moved to Spring Hill Fl. last August. So this is my first real weather experience from a named storm. Officially.


Congrats! Lucky for you it was a very mild experience. They won't all be. Just north of you and we hardly got any rain.
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Quoting Patrap:


From the Mouths of our Future to America's ear's

A message,

Houma students deliver Louisiana's message to rest of country

Its the middle of July and Vandebilt Catholic High School in Houma is locked tight, the students enjoying their summer vacation.


Usually just a lurker, but I'll break my silence on this one. My wife is an English teacher at this school. Lots of good kids here that are very active in the community. Quite refreshing.
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Hmmm ... lurking in Gulf Breeze ... should I make preparations for Bonnie (beer/chips/salsa run) or just kick back and enjoy this blog?
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Quoting nolacane2009:
I have a question for whoever would like to answer. Who thinks that this year will produce as many hurricanes or tropical storms as they say this year?


As who say???
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting StormW:


OMG!

Forgot about dem!


and fender skirts
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I have a question for whoever would like to answer. Who thinks that this year will produce as many hurricanes or tropical storms as they say this year?
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Quoting atmosweather:
Still no W-erlies to be found...only 10-15 miles S of the center.


It was really hard to find them all day. The only one I could find was Homestead right before landfall. Very unusual for a TS.
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Quoting StormW:


Yeah...more like a vent window on an automobile.


you really showing your age now lol
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Quoting jasoniscoolman2010x:
Wow. Look at that big ball of convection over NW Mali... that's pretty much desert, right there, and a big source of SAL dust... we could be seeing pretty much the end of SAL outbreaks for the next little while...
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From the Mouths of our Future to America's ear's

A message,

Houma students deliver Louisiana's message to rest of country

Its the middle of July and Vandebilt Catholic High School in Houma is locked tight, the students enjoying their summer vacation.
Member Since: July 3, 2005 Posts: 426 Comments: 128648
Good stuff Storm. That is one small window.
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Still no W-erlies to be found...only 10-15 miles S of the center.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
I don't think Bonnie is done call me crazy but it looks like she has a little kick left and I think she'll stay at least a depression until landfall
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Quoting LADobeLady:


It's not just Transocean it was MMS (now BOE) and the USCG for missing that during inspections or turning a blind eye to it. That is the exception on rigs NOT the norm.
It seems there is a lot of "blame" to be shared around in this situation. I think a culture of "laissez faire" permeated the minerals/oil prospecting industry during the Bush years, so that people / companies / agencies were pretty much guided by whatever personal principles they had. If they didn't have any or many, they could easily be subverted by those who only cared about how much money they could make.

I'm getting the impression from things I have read here and elsewhere that because the dollar was the bottom line a lot of safety measures that should have been put in place just were not there. Poor inspections by gov't officials so BP wouldn't have to pay so much to upgrade things; reduction of reinforcers in the concrete by Halliburton so BP wouldn't have to pay so much; turning off alarms so work would continue uninterrupted and BP wouldn't have to pay so much; all this while oil prices were driven to their highest level ever and BP could have afforded to pay the money that was needed to keep things being done safely. Now, in hindsight, BP looks to be paying more than it could ever have expected for it's short-cutting. But it was all part and parcel of a "group-think" that felt Big Oil should be able to do pretty much what it wanted.

That's why I laugh at people who castigate Mr. Obama for not doing enough quickly enough and who want to blame the oil spill problems on the Coast Guard. The problems that created this situation go so much deeper.... and have been going on for many, many years.
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Nearing the circulation; pressure at 1012.2mb.

000
URNT15 KNHC 240125
AF305 0603A BONNIE HDOB 24 20100724
011530 2543N 08304W 9250 00807 0138 +219 +216 088005 006 016 001 00
011600 2545N 08304W 9248 00807 0137 +220 +215 099004 005 016 001 00
011630 2546N 08304W 9248 00807 0137 +220 +215 105004 005 017 000 00
011700 2548N 08304W 9250 00804 0136 +220 +215 084003 003 017 000 00
011730 2550N 08304W 9250 00804 0136 +220 +214 073003 003 017 000 00
011800 2551N 08304W 9249 00805 0136 +220 +214 069002 003 017 000 00
011830 2553N 08304W 9249 00804 0135 +220 +214 077002 003 017 000 00
011900 2554N 08304W 9249 00804 0134 +220 +214 089003 003 017 000 00
011930 2556N 08304W 9249 00804 0135 +220 +213 100003 003 017 000 00
012000 2558N 08304W 9248 00805 0136 +219 +213 079002 002 017 000 00
012030 2559N 08304W 9249 00802 0134 +218 //// 055003 004 019 001 01
012100 2601N 08304W 9251 00799 0133 +216 //// 036003 004 021 000 01
012130 2602N 08304W 9245 00805 0132 +220 //// 042006 007 021 000 01
012200 2604N 08304W 9250 00801 0131 +221 //// 048006 006 020 000 01
012230 2605N 08304W 9250 00798 0129 +224 //// 061004 005 020 001 01
012300 2607N 08304W 9249 00801 0128 +223 //// 038005 007 020 000 01
012330 2608N 08304W 9246 00802 0127 +221 //// 055006 007 021 000 01
012400 2610N 08304W 9249 00797 0126 +224 //// 064006 007 020 000 01
012430 2612N 08304W 9251 00794 0124 +223 //// 041006 006 023 000 01
012500 2613N 08304W 9246 00798 0122 +229 +226 043007 009 024 000 00
$$
;
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Quoting P451:
60HR IR Loop - Bonnie. Ending 845PM ET.



Best loops on the blog! P451, I don't know how you do it, but those loops are fantastic!
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The Mayans are not Happy with BP atall.

Were DOOMED
Member Since: July 3, 2005 Posts: 426 Comments: 128648
Wow, off topic, but did ya see this?

2 hours ago 7.4 Moro Gulf, Mindanao, Philippines Map
2 hours ago 7.6 Moro Gulf, Mindanao, Philippines Map
3 hours ago 7.3 Moro Gulf, Mindanao, Philippines Map

http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/quakes_all.php
Member Since: June 12, 2005 Posts: 6 Comments: 8186

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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.