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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Quoting MiamiHurricanes09:
Recon heading back towards the center.
they just want to make sure shes not up to any mischief
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AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting vortextrance:
Looks like Bonnie will keep doing what she has been doing which is barely hang on. This is unfortunate. It looked like she might just die but no such luck for the northern Gulf coast. Not much threat of significant strengthening. Same story with the dry air and shear. IF nothing else Bonnie has been a very interesting storm.
that it has been
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Quoting vortextrance:


Is there a wave near Hispanola or is all the convection associated with the ULL? The wave coming off Africa in a couple of days is a monster.


No its mainly just mid and upper level energy associated with the ULL and some upper divergence helping to fuel the storms.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
807. IKE
There it goes...literally.....

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Thx Storm...sorry for the redundant questions but I'm learning alot!!
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Quoting gordydunnot:
Jason what's this obsession with Africa do you vacation there.
Some of us are watching for potential AEWs that may later become CV TC fodder....

Quoting Hurricanes101:
694. eye 12:31 AM GMT on July 24, 2010

not with the percentage symbol behind it

guess you are a troll too, I am done debating this lol
Yeah, eye's a troll, and a long-time one to. Practically a respectable troll....

Hey there, eye; haven't seen u in the blog for a while.. how's tricks?

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Quoting Tazmanian:


heh

LoL :)
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Quoting TexasHurricane:


You crack me up..... :)


Well I'm glad to bring ya a smile. :)
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Quoting atmosweather:


Area of disorganized showers and t-storms near Hispanola will have to be watched this weekend and into early next week when conditions improve...also a decent tropical wave moving towards the Antilles and one moving off the African coast have slight chances.


Is there a wave near Hispanola or is all the convection associated with the ULL? The wave coming off Africa in a couple of days is a monster.
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Quoting StormW:


Always.


Wow, what happened. Anyway, when was the first year that the NHC began labeling tropical disturbances as "invests"? Don't remember studying that in the early 90's. If you don't know off hand don't worry about it. I can research it myself.......thanks man.
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Quoting WeatherNerdPR:

Sedn?! First it was worng and now sedn?! LOL


heh
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Quoting Tazmanian:




well sedn JFV in a row boat and he find out for us

Sedn?! First it was worng and now sedn?! LOL
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Recon heading back towards the center.
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Looks like Bonnie will keep doing what she has been doing which is barely hang on. This is unfortunate. It looked like she might just die but no such luck for the northern Gulf coast. Not much threat of significant strengthening. Same story with the dry air and shear. IF nothing else Bonnie has been a very interesting storm.
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794. xcool
lmao
Member Since: September 26, 2009 Posts: 2 Comments: 15649
Quoting TankHead93:
What is next to possibly develop in the tropics?


Area of disorganized showers and t-storms near Hispanola will have to be watched this weekend and into early next week when conditions improve...also a decent tropical wave moving towards the Antilles and one moving off the African coast have slight chances.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting TankHead93:
What is next to possibly develop in the tropics?




well sedn JFV in a row boat and he find out for us
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What is next to possibly develop in the tropics?
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Quoting Tazmanian:
oh the heck put bonnie on death row oh did he killed

Taz... Honestly... you crack me up. Always have! Thanks for being on this blog...
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Quoting StormW:


How much longer are they giving her over water?


24-30 hours.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting homelesswanderer:


"OH GOODIE! I got it right!" I just squealed that aloud and Hubby looked at me like I was crazy. Lol. But I'm learning. Pat myself on the back. :)


Lol, yes definitely give yourself a pat on the back :)
Member Since: November 24, 2005 Posts: 635 Comments: 26618
I think about 36 hrs....
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oh the heck put bonnie on death row oh did he killed
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784. Halyn
Quoting StormSurgeon:


What do you call an entity that rises from the dead........a Phoenix.........or a zombie?
A Poenix rises from ashes .. a zombie crawls out of the grave intact .. kinda like a troll. :)
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Quoting Jeff9641:
TD Bonnie looks like she went POOF.
Well she has a closed surface circulation exhibiting a pressure of 1010mb and winds of 31 knots so it obviously hasn't gone "POOF".
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They also launched a 19 Z sonde at Tampa today. This upper level dry is what Bonnie has been contending with all along. This sonde went directly into her NW outflow.

No way can she maintain deep convection...

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781. xcool
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 24th day of the month at 00:20Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 305)
Storm Number & Year: 03L in 2010
Storm Name: Bonnie (flight in the North Atlantic basin)
Mission Number: 6
Observation Number: 06
A. Time of Center Fix: 24th day of the month at 0:02:40Z
B. Center Fix Coordinates: 26°14'N 82°39'W (26.2333N 82.65W)
B. Center Fix Location: 56 miles (91 km) to the WSW (241°) from Fort Myers, FL, USA.
C. Minimum Height at Standard Level: 779m (2,556ft) at 925mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 31kts (~ 35.7mph)
E. Location of the Estimated Maximum Surface Wind: 21 nautical miles (24 statute miles) to the WNW (297°) of center fix
F. Maximum Flight Level Wind Inbound: From 65° at 37kts (From the ENE at ~ 42.6mph)
G. Location of Maximum Flight Level Wind Inbound: 126 nautical miles (145 statute miles) to the NW (313°) of center fix
H. Minimum Sea Level Pressure: 1010mb (29.83 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 23°C (73°F) at a pressure alt. of 763m (2,503ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 24°C (75°F) at a pressure alt. of 755m (2,477ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 22°C (72°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 925mb (If this vortex is from mid 1990's or earlier 925mb might be incorrect. See note.)
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 37kts (~ 42.6mph) in the northwest quadrant at 23:22:40Z
Sea Level Pressure Extrapolation From: 925mb
Member Since: September 26, 2009 Posts: 2 Comments: 15649
well find out at 11pm
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Quoting homelesswanderer:


"OH GOODIE! I got it right!" I just squealed that aloud and Hubby looked at me like I was crazy. Lol. But I'm learning. Pat myself on the back. :)


You crack me up..... :)
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Storm....what's your thoughts on TD? is she a goner? Bloggers take it easy on me....Eager to learn here!!
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they actually did the deactivation 1st and then put the 00Z coordiantes in lol


tells me that the atcf may have deactivated the wrong thing
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Quoting hcubed:


If they'll stop with the "I won!!!" posts, we'll stop calling them out.

So many people get on here, post accurate information, and don't brag about their "success".


Um. Don't look at my last post. I be shamed. :(
Lol.
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000
WHXX01 KWBC 240033
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0033 UTC SAT JUL 24 2010

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE BONNIE (AL032010) 20100724 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
100724 0000 100724 1200 100725 0000 100725 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 26.3N 82.6W 27.5N 85.2W 28.8N 87.2W 30.0N 89.4W
BAMD 26.3N 82.6W 28.4N 86.2W 31.0N 89.1W 33.7N 90.7W
BAMM 26.3N 82.6W 27.9N 85.7W 29.7N 88.3W 31.7N 90.4W
LBAR 26.3N 82.6W 27.8N 85.9W 29.9N 88.8W 32.1N 90.6W
SHIP 30KTS 31KTS 33KTS 36KTS
DSHP 30KTS 31KTS 33KTS 31KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
100726 0000 100727 0000 100728 0000 100729 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 31.1N 91.0W 33.4N 93.5W 36.4N 94.5W 39.9N 93.3W
BAMD 35.9N 90.7W 38.1N 85.2W 37.1N 76.6W 34.6N 69.6W
BAMM 33.4N 91.5W 36.4N 91.0W 38.0N 87.1W 37.5N 81.1W
LBAR 34.1N 91.0W 36.9N 87.7W 37.3N 79.3W 37.1N 67.4W
SHIP 40KTS 46KTS 49KTS 51KTS
DSHP 28KTS 27KTS 27KTS 28KTS

...INITIAL CONDITIONS...
LATCUR = 26.3N LONCUR = 82.6W DIRCUR = 295DEG SPDCUR = 15KT
LATM12 = 24.8N LONM12 = 79.7W DIRM12 = 304DEG SPDM12 = 18KT
LATM24 = 23.1N LONM24 = 75.9W
WNDCUR = 30KT RMAXWD = 30NM WNDM12 = 35KT
CENPRS = 1010MB OUTPRS = 1014MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0N
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772. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15649
Quoting Hurricanes101:


yup and they deactivated it without the 00Z coordinates

again I think its a mistake on their part
Agreed.
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Quoting hcubed:


If they'll stop with the "I won!!!" posts, we'll stop calling them out.

So many people get on here, post accurate information, and don't brag about their "success".
Ding! Ding! Ding! Ding! Ding! Ding! Winner!
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Quoting MiamiHurricanes09:
Interesting...the ATCF site input the pressure and wind speed from the Vortex message into their latest "update", if you will.

AL, 03, 2010072400, , BEST, 0, 263N, 826W, 30, 1010, TD,

invest_DEACTIVATE_al032010.ren


yup and they deactivated it without the 00Z coordinates

again I think its a mistake on their part
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NYC is in the clear now. Cloud top increased to 45,000 ft but rotation weakened.

Severe thunderstorm warnings in place now.

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Quoting Levi32:


Exactly.


"OH GOODIE! I got it right!" I just squealed that aloud and Hubby looked at me like I was crazy. Lol. But I'm learning. Pat myself on the back. :)
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Quoting Orcasystems:


Dead and Vortex Plot.. does not compute does it?



They only issue a vortex if the system in question has a closed circultion...BUT...I also believe that they will do it even if the system is not a TC because of other reasons.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting IKE:


Go ahead and shut the office down.


Look at your blob dying off.....quickly....


LOL.
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bonnies convective core,lol...has fallen apart,notice the out flow boundry headed sw away from the coppased convection.
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Quoting Hurricanes101:
As pathetic as the overreactions to some systems are, it is even more pathetic when people bait them and try to make fun of them if they are wrong

grow up people, its ok to be wrong, its not ok to throw other peoples' predictions in their faces


If they'll stop with the "I won!!!" posts, we'll stop calling them out.

So many people get on here, post accurate information, and don't brag about their "success".
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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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