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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Ouick,..get the Paddles,!,

and CLEAR !!!!


"Cha..Chunk"..

Beep,..beep,...beep..beep..





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Was that epicenter in the mantle.
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408. JLPR2
Quoting MiamiWarnings:
interesting, why doesn't the parrallel show the strom, im sracthing my head here, :(


that's the parallel dude! XD
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Quoting stormpetrol:

+1 KOTG , I still think climatology, upper atmospheric conditions and SST rules the roost in terms of predicting and forcasting cyclones or developing ones, yet there is plenty that is unknown. It's Nature's secret!
Yet, none of the factors, alone, means a thing. SSTs might be great (see exhibit B...onnie) but other factors nix it.

In this line of thinking, SSTs that are usually 28 C, but anomalously high by 2 C doesn't necessarily mean more activity. Everything else must come into line...a lack of shear (thanks La Nina), rain in the Sahel, a couple of good MJO pulses at the right moment, lucky placement of upper level features, etc.
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405. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
403. JLPR2
Quoting MiamiWarnings:


thanks, twink. now, i know its a very long range froecast, but just for laughs, if you had to speculate on its track beyond PR, given' the pattern shown on the run, where would you think it would go? just out of curiosity. TIA, :).

Levi, you are also welcome to take a stab at this question, if you'd like.


Nowhere, cause its not coming to PR the 8th of August, I am free and enjoying my vacations that day, so no. XD
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402. HadesGodWyvern (Mod)
[REMOVED]
reason: already posted.
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Quoting Patrap:
Get to close to a Black Hole...and one can slip past the event horizon..

And just Poof.

Disappear..

Just Like Dat.

"Snap's finger's"..


Snap!





Isn't that call interaction with land?
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Quoting MiamiWarnings:


thanks, twink. now, i know its a very long range froecast, but just for laughs, if you had to speculate on its track beyond PR, given' the pattern shown on the run, where would you think it would go? just out of curiosity. TIA, :).

Levi, you are also welcome to take a stab at this question, if you'd like.


well it seems based on the pattern at the end of the model that the system would go on a more nw motion after last image. This will change frequently if this system even develops at all. This far out in 2007 it had what would become hurricane dean making landfall on the east coast and it ended up making landfall in i think guatemala or belize
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Quoting Levi32:


For the SW Atlantic and Gulf of Mexico -1.8mb is a pretty dang good 9-month average anomaly. What matters more is the shape and location of the below-normal pressures. It's entirely believable that 2010 could have lower pressures than the analog years....but the overall pattern is similar.

And I'll post this image again from the CPC, the typical positive NAO pattern in the summer is more of a tripole pattern that actually favors lower pressures over the tropics. The numerical index of the NAO is not a cut and dried indicator of the pattern in the Atlantic during the hurricane season. The pattern is much more flexible and the oscillation can take many forms.

Furthermore, I can't really see there being anything but lower than normal pressures in the tropical Atlantic with SSTs as warm as they are, can you? Pressures are already way above normal in the Pacific like they should be due to the cold water. That has to be balanced out in the Atlantic and Indian Oceans where the water is warm.

What ur saying is making me think we should see some hyperactivity in the NInd and SInd later this year into next year....
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000
WEPA42 PHEB 232301
TIBPAC

TSUNAMI BULLETIN NUMBER 001
PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 2301Z 23 JUL 2010

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC
OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...
WASHINGTON...OREGON AND CALIFORNIA.

... TSUNAMI INFORMATION BULLETIN ...

THIS BULLETIN IS FOR INFORMATION ONLY.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY
NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE
DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND
ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME - 2251Z 23 JUL 2010
COORDINATES - 6.5 NORTH 123.6 EAST
DEPTH - 581 KM
LOCATION - MINDANAO PHILIPPINES
MAGNITUDE - 7.3

EVALUATION

A DESTRUCTIVE TSUNAMI WAS NOT GENERATED BASED ON EARTHQUAKE AND
HISTORICAL TSUNAMI DATA.

THIS WILL BE THE ONLY BULLETIN ISSUED FOR THIS EVENT UNLESS
ADDITIONAL INFORMATION BECOMES AVAILABLE.

THE JAPAN METEOROLOGICAL AGENCY MAY ALSO ISSUE TSUNAMI MESSAGES
FOR THIS EVENT TO COUNTRIES IN THE NORTHWEST PACIFIC AND SOUTH
CHINA SEA REGION. IN CASE OF CONFLICTING INFORMATION... THE
MORE CONSERVATIVE INFORMATION SHOULD BE USED FOR SAFETY.

THE WEST COAST/ALASKA TSUNAMI WARNING CENTER WILL ISSUE PRODUCTS
FOR ALASKA...BRITISH COLUMBIA...WASHINGTON...OREGON...CALIFORNIA.
...SP...
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Member Since: July 15, 2006 Posts: 178 Comments: 56021
Quoting gordydunnot:
Play request Tubular Bells I'm feeling possessed by the Internets. Thank You, GW


Wowiee, now that's a blast from the past request.

While not heavy rain, Bonnie has brought steady drips to my area. It's been steady since about 11:30 am here.
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Quoting Twinkster:
if anyone is interested about the GFS's ability to see cape verde hurricanes in the long range. They nailed the formation of Hurricane Dean 2007 from about the same time out that this disturbance is supposed to form. The GFS has a very good reputation with regards to accurately developing cape verde storms


Rita wasn't a Cape Verde but the GFS had the TX/LA coast landfall nailed 5 days out. Obviously not many people believed it, hence the TEXODUS. :) But no I'm not advocating basing your preps on any model 5 days out.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Keep in mind that the eastern Pacific is behind schedule so far with 4 named storms, and the west Pacific is having possibly the slowest start to their typhoon season in history. The Indian Ocean is near-normal I believe with the 3 storms they had in their first season peak. The Atlantic is ahead of schedule with 2.

What does this tell us? The heat pumped into the tropics by the El Nino this past winter is not just going to go away. With the Pacific shut down the heat has to be released somewhere else. It has been all bundled up in the Atlantic which is why we've been seeing the record SSTs and very low surface pressures, the lowest found on the globe right now relative to normal. That heat has to go somewhere to balance the earth's energy budget. The La Nina gives the atmosphere a mechanism with which to deal with that excess heat, and that mechanism is tropical cyclones.
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Magnitude 7.3 - MORO GULF, MINDANAO, PHILIPPINES
2010 July 23 22:08:11 UTC

Versión en Español

* Details
* Summary
* Maps
* Scientific & Technical
* Tsunami

Earthquake Details

* This event has been reviewed by a seismologist.

Magnitude 7.3
Date-Time

* Friday, July 23, 2010 at 22:08:11 UTC
* Saturday, July 24, 2010 at 06:08:11 AM at epicenter
* Time of Earthquake in other Time Zones

Location 6.708°N, 123.479°E
Depth 604.5 km (375.6 miles)
Region MORO GULF, MINDANAO, PHILIPPINES
Distances 100 km (65 miles) SW of Cotabato, Mindanao, Philippines
120 km (75 miles) S of Pagadian, Mindanao, Philippines
155 km (95 miles) E of Zamboanga, Mindanao, Philippines
915 km (570 miles) SSE of MANILA, Philippines
Location Uncertainty horizontal +/- 4.5 km (2.8 miles); depth +/- 6.7 km (4.2 miles)
Parameters NST= 93, Nph= 93, Dmin=235.6 km, Rmss=0.83 sec, Gp= 22°,
M-type=teleseismic moment magnitude (Mw), Version=7
Source

* USGS NEIC (WDCS-D)

Event ID us2010zbbz
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Quoting MiamiWarnings:


thanks, twink. now, i know its a very long range froecast, but just for laughs, if you had to speculate on its track beyond PR, given' the pattern shown on the run, where would you think it would go? just out of curiosity. TIA, :).

Levi, you are also welcome to take a stab at this question, if you'd like.
the question is where do you want it to go
Member Since: July 15, 2006 Posts: 178 Comments: 56021
Quoting Levi32:


A hint at things to come.

The sad part is, that's the day after my birthday. :(
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389. HadesGodWyvern (Mod)
Earthquake Information (Earthquake Information)
Issued at 07:33 JST 24 Jul 2010

Occurred at (JST) Latitude
(degree) Longitude
(degree) Depth Magnitude Region Name
07:08 JST 24 Jul 2010 6.7N 123.5E 590km 7.1 Philippines and its Vicinity
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Quoting earthlydragonfly:


So they might not know that you have them on ignore?? Unless you say Poof of course..
That's how it works.
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387. JLPR2
Quoting Twinkster:


I was going to post that XD
And I was going to say that is as real as the patience and harmony that characterizes this blog. XD
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Quoting SQUAWK:


Yes


So they might not know that you have them on ignore?? Unless you say Poof of course..
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Quoting earthlydragonfly:
When you ignore someone can they read what you write on the blog?


Yes
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Quoting HouGalv08:
I have to agree TH. Late May gave us some strong tropical waves, June a bit of a lull, July we had Alex, almost Bonnie south of La., Bonnie, almost Collin in the BOC. Warnings, shots across the bow. Get yourselves ready for whats to come. We have been warned.
Word.

Watch the tracks. We've seen the two main ones for the season. IMHO
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Quoting Levi32:
New EUROSIP July forecasts for August-September-October still look bad for the Caribbean and United States. The forecast hasn't changed for months and it is verifying before our very eyes. The storms will come from this pattern. It is almost unavoidable.

Sea-level Pressure:



Precipitation:



2m Temperature:



Huge amount of heat and not a lot of shear over the Atlantic Basin through the heart of the season...something always gives in that situation.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Play request Tubular Bells I'm feeling possessed by the Internets. Thank You, GW
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Quoting beell:


It saw Bonnie's ULL pretty well if you ask me. It also saw the next one in line developing over Hispaniola.

:]


I meant it didn't show a tropical storm. At least I don't think it did. But yes I was following pre-Bonnie for a while now. And the next one also. CMC been iffy about it but has been showing both for a while too. :)
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Quoting Twinkster:


A hint at things to come.
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Quoting BahaHurican:
Ladies, this is just proof that not every relationship you get into is going to turn out right... sometimes they just take everything you got then rip you apart....

LMAO!! +1 best post of the evening, need a little humor to lighten up the spirits along with the Coors light of course!
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Quoting CybrTeddy:


We defiantly needs to watch this wave over the next couple of days. I'm too lazy to check but are any other models predicting development? We Also need to watch the area around Bermuda as Levi mentioned earlier.
CMC not showing development.
Parallel GFS not showing development.
Operational GFS is showing development, however it takes it over the northern Antilles as a sharply inverted tropical wave.
Operation GFS 144 hours.

NOGAPS showing weak development but it is very south.
NOGAPS 144 hours


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Quoting Patrap:
Get to close to a Black Hole...and one can slip past the event horizon..

And just Poof.

Disappear..

Just Like Dat.

"Snap's finger's"..


Snap!







Black hole or the dreaded "Blog Hole"?
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Quoting stormpetrol:

+1 KOTG , I still think climatology, upper atmospheric conditions and SST rules the roost in terms of predicting and forcasting cyclones or developing ones, yet there is plenty that is unknown. It's Nature's secret!
and she's good at keeping it that way
Member Since: July 15, 2006 Posts: 178 Comments: 56021
Quoting Levi32:
New EUROSIP July forecasts for August-September-October still look bad for the Caribbean and United States. The forecast hasn't changed for months and it is verifying before our very eyes. The storms will come from this pattern. It is almost unavoidable.

Sea-level Pressure:



Precipitation:



2m Temperature:



Oh boy. Big Sigh.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
When you ignore someone can they read what you write on the blog?
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370. beell
Quoting homelesswanderer:


Thanks. Was wondering why it didn't see Bonnie and yet it looks like they had the end of the track and strength correct. Cmc didnt do bad either. Except of course over doing the strength. The gfs never seems to see anything this season.


It saw Bonnie's ULL pretty well if you ask me. It also saw the next one in line developing over Hispaniola.

:]
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Well According to Sat imagery on the Rainbow loop we have a squall line moving into "The Caymans" tonight, should bring some rain and gusty winds , winds been out the of SSW, WSW and W all afternoon!
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Quoting IKE:


Bonnie and that ULL....never could get away from each other. A lot of experts were saying it probably would, but it never really did.
Ladies, this is just proof that not every relationship you get into is going to turn out right... sometimes they just take everything you got then rip you apart....
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Quoting atmoaggie:
Okay. If that remains as is, what TCs form will favor the Atlantic. But, would you say we see an uptick in total ACE worldwide, or remaining low?



Given the more hostile conditions that simply exist in the Atlantic (land, dust, shear, etc.), relative to the Super typhoon-generating West Pac, my leaning is to stay on a generally low total ACE. Does that really equate to a 20 named storm season, or close? I don't think so.

For this season to jump to the Northern Hemisphere ACE values of '98, '05, etc. (lower dots) would be quite a leap from recent or current levels. Almost appears to be something at play we aren't considering. At no time in the last 30 years, according to that plot, has N Hemisphere ACE jump from the values it is now to those of the analogue years (at least the ones from the last 30 years), though '91 would be the steepest. Time will tell.


You don't need a global ACE that high to necessarily correspond to a hyperactive season in the Atlantic. The global ACE this year will remain generally low yes, because the Pacific basins will be below normal and the Indian looked about normal in its first season peak with 3 storms. The Atlantic contributes only a small amount to the global ACE, largely because of the west Pacific, which you mentioned, which is the ACE powerhouse of the world.

We're going into a very cold plunge right now globally with this La Nina and cold PDO lining up. 2005 had high ACE because the Pacific hurricane seasons were both near-normal along with the above-normal Atlantic because we were in a warm PDO with lots of heat to share. 1998 didn't go as cold as fast during the summer, and waited until later for the La Nina to really take over that winter. Look at where the ACE graph is by 1999....way down there.

The fact is that the overall global pattern is going to be different over the next couple decades than at any time during the graph you posted. A cold PDO like this can generate a really low global ACE because of the lack of heat, but what heat is available is all bundled up in the Atlantic, where tropical activity usually sees bursts. That is the place to go for global tropical activity this year. Atlantic is the focus-point.
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if anyone is interested about the GFS's ability to see cape verde hurricanes in the long range. They nailed the formation of Hurricane Dean 2007 from about the same time out that this disturbance is supposed to form. The GFS has a very good reputation with regards to accurately developing cape verde storms
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Quoting Twinkster:
18Z GFS shows cape verde hurricane situated north of puerto rico on august 8th. Begins developing the system about a week from now by the cape verde islands

http://www.nco.ncep.noaa.gov/pmb/nwpara/analysis/carib/gfs/18/index_ten_l_loop.shtml


GFS naturally does better with CV systems, we'll have to watch this as well. VERY long range however.
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Quoting MiamiHurricanes09:
The sea is too dry, eh? Is the ice too hot? Is the air too heavy?


The beer is too cold,
The daquiris too fruitiful
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Get to close to a Black Hole...and one can slip past the event horizon..

And just Poof.

Disappear..

Just Like Dat.

"Snap's finger's"..


Snap!





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Quoting MiamiHurricanes09:
It's always an interesting week during hurricane season.

True dat!
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Quoting atmosweather:


"Well I believe you may get your headlines, Mr. Ismay"


Call me Bruce, really. :)
Member Since: August 15, 2008 Posts: 10 Comments: 3665

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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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