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:
Despite having an unfavorable environment in the upper levels I would give the weak trough over Hispañiola a "10%" chance. The GFS appears to take upper level winds to around 5-15 knots around the system in 42 hours so it may have a slight chance.



yup
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Quoting gordydunnot:
It's got one thunderstorm.


1.5 seems
Member Since: July 3, 2005 Posts: 423 Comments: 128240
It's got one thunderstorm.
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Quoting Tazmanian:
new two comes soon
Despite having an unfavorable environment in the upper levels I would give the weak trough over Hispañiola a "10%" chance. The GFS appears to take upper level winds to around 5-15 knots around the system in 42 hours so it may have a slight chance.
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Well, looking at the models I do believe we'll have our first Cape Verde storm within the next two weeks.. possibly Hurricane. I also believe there might be a tropical cyclone off the Eastern coast before month's end. Very interesting next two weeks!
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.."Thats no Open Wave"..

Dats a Space Station,..!
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting zoomiami:
First chance I've had to post on the blog today -- we had one big blast of wind and rain around 11:00 today - when Bonnie came ashore in Cutler Bay. My office isn't far from there. The rain was going all over the place, down, sideways, circles, was interesting to watch.

The winds were definitely higher than normal, but not much more than some of the intense thunderstorms we get in afternoons.

There was quite a bit of thunder. I thought I read that there is generally not thunder and lightening during tropical storms.


I think that would be hurricanes, because the very strong horizontal winds of a hurricane limit the process by which lightning is generated. In a weak tropical storm there is still a lot of vertical component to the air motions because winds are weaker, resulting in less horizontal component. Thus, lightning can still be generated in large amounts.
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Quoting ShenValleyFlyFish:
OK for CHARGING batteries on laptops, cell phones etc but not recommended to attempt to operate electronics. I've got one and when I am on a run I will turn off my computer or phone and charge them up but when I turn them on I make sure they are disconnected.


Excellent point. Yeah I was mainly thinking about charging and such. Most of my things don't have a car charger. I'd like to know more about those 3g? things you can get to go on the internet when your house wifi is out. I was thinking of getting the new IPAD that came with unlimited AT&T access for 29.99. No contract. That lasted about 4 days then switched it and limited the access. Glad I didn't get one. Bummer though. :(
Member Since: August 15, 2008 Posts: 10 Comments: 3665
we are here today too play say are last words too what was are TS



any last words any one be for we put this storm too rest
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"Boinnnng"


Member Since: July 3, 2005 Posts: 423 Comments: 128240
Hot Tower casting KOTG?

Very cool..
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting CybrTeddy:


Look between Africa and the Caribbean.. very interesting.


Indeed, would not be surprised at all to see that. This is the first run it has shown up.
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new two comes soon
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Quoting atmosweather:
"Recon descending; moving towards the WSW."

SE-ward
Oops! Now I messed up! LOL, got my coordinates mixed up.
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"Recon descending; moving towards the WSW."

SE-ward
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Really dead ?

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Quoting Levi32:
18z GFS Parallel still showing the potential for homegrown mischief during the first week of August off the SE US coast and in the northern Gulf of Mexico as the mean trough over the Canadian Maritimes sends down a couple fronts to get stalled under the nose of an upper ridge, a conducive pattern for warm-core lows to develop.

Day 11:



Look between Africa and the Caribbean.. very interesting.
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Member Since: July 15, 2006 Posts: 171 Comments: 53787
First chance I've had to post on the blog today -- we had one big blast of wind and rain around 11:00 today - when Bonnie came ashore in Cutler Bay. My office isn't far from there. The rain was going all over the place, down, sideways, circles, was interesting to watch.

The winds were definitely higher than normal, but not much more than some of the intense thunderstorms we get in afternoons.

There was quite a bit of thunder. I thought I read that there is generally not thunder and lightening during tropical storms.
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Quoting gordydunnot:
What's left of Bonnie appears to be west bound not a good direction but she may be in an odd relationship and like Mr ULL.


They waiting for after Sunset...to er,.."Mingle" again.

Member Since: July 3, 2005 Posts: 423 Comments: 128240
i would if Bonnie was the ULL the hole time
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"Recon descending; moving towards the WSW."

SE-ward
Member Since: September 24, 2005 Posts: 33 Comments: 9265
What's left of Bonnie appears to be west bound not a good direction but she may be in an odd relationship and like Mr ULL.
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Quoting Ameister12:
If Bonnie were do dissipate, could it redevelop?
Unlikely. The upper level environment is forecasted to remain unfavorable for development. Dry air is also playing a role in diminishing thunderstorm activity within Tropical Depression Bonnie.
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Quoting Ameister12:
If Bonnie were do dissipate, could it redevelop?



nop
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Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting Ameister12:
Bonnie looks like crap, soooo.... next?


looks like a front
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BBL later.
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If Bonnie were do dissipate, could it redevelop?
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Next region to get "schwacked" is...Newfoundland :)

Non tropical...but a huge storm for this time of the year.

Link
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Recon descending; moving towards the SE/ESE.

000
URNT15 KNHC 232325
AF305 0603A BONNIE HDOB 12 20100723
231530 2802N 08433W 8835 01223 0160 212 043 068028 029 /// /// 03
231600 2801N 08435W 9298 00776 0158 225 155 078030 031 /// /// 03
231630 2759N 08434W 9323 00752 0156 228 168 081029 030 021 001 03
231700 2758N 08432W 9278 00792 0155 221 172 080030 030 023 000 00
231730 2757N 08431W 9234 00834 0155 216 173 083028 029 026 000 00
231800 2757N 08429W 9250 00820 0157 215 182 081024 025 027 000 00
231830 2756N 08428W 9249 00820 0157 215 180 074025 026 030 001 00
231900 2754N 08426W 9246 00835 0171 217 172 072026 027 030 000 00
231930 2753N 08425W 9250 00834 0167 216 166 070028 030 029 000 00
232000 2752N 08424W 9249 00820 0157 216 165 066030 031 028 000 00
232030 2751N 08422W 9250 00820 0157 215 172 067030 031 028 000 00
232100 2750N 08421W 9250 00818 0155 218 170 065032 033 027 000 00
232130 2749N 08420W 9245 00823 0154 226 147 065034 034 027 000 00
232200 2747N 08418W 9249 00819 0153 230 140 065036 037 027 000 00
232230 2746N 08417W 9250 00818 0152 231 146 065037 037 026 000 00
232300 2745N 08416W 9246 00823 0152 229 158 065036 037 026 000 00
232330 2744N 08414W 9248 00819 0152 228 156 064035 036 026 000 00
232400 2743N 08413W 9248 00820 0154 226 147 061035 035 027 000 00
232430 2742N 08412W 9249 00819 0152 229 141 062032 033 027 000 00
232500 2740N 08411W 9248 00820 0152 229 137 055032 032 027 000 00
$$
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478. srada
Quoting jasoniscoolman2010x:
what up with this tropical low here.


Looks like something off the coast of NC and SC
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Quoting CaicosRetiredSailor:
Chew Mail Pouch
See Rock City
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Quoting homelesswanderer:
Speaking of preparedness. I just heard about a thing you plug into your cars lighter/accessory port and you can plug things into like a regular house plug. Think they're called converters? Anyway sounds like a neat thing to have. I'm probably the last person on the planet to know about this. :)
Might power a handheld fan at the most. Only way to go is with a backup genny, IMO. Had one after Ike blew thru Houston in '08, and what a godsend. 7kw wired to the house kept it ALL running, except the main A/C unit. We went 14 days that way. Stored away 80 gallons fuel before it hit. Eco drive on the Honda let us use very little fuel, and was quiet too, compared to all the other "screamers".
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Quoting stormpetrol:
TD Bonnie is not an open wave you can clearly see the LLC exposed on Visible, Bonnie, I think will become at least a 60 mph TS again before making landfall, just my opinion only.



shhhshh.....!


They will see and catch on and where will we be then?

Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting atmosweather:


Oops yeah I was in the wrong column LOL. IMO this is an open trough.
Lol. Looks that way to me too.
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TD Bonnie is not an open wave you can clearly see the LLC exposed on Visible, Bonnie, I think will become at least a 60 mph TS again before making landfall, just my opinion only.
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Quoting MiamiHurricanes09:
Recon descending.

000
URNT15 KNHC 232315
AF305 0603A BONNIE HDOB 11 20100723
230530 2744N 08458W 4824 06201 0366 -056 -101 149015 016 003 000 03
230600 2745N 08456W 5050 05842 0341 -040 -067 133015 016 /// /// 03
230630 2746N 08453W 5272 05496 0321 -028 -037 142013 015 002 000 03
230700 2747N 08451W 5273 05504 0323 -021 -038 143013 013 001 000 00
230730 2748N 08450W 5288 05478 0321 -020 -039 143013 014 002 000 00
230800 2748N 08448W 5278 05494 0322 -020 -038 139014 015 007 000 03
230830 2749N 08446W 5285 05484 0322 -025 -033 136016 016 003 000 03
230900 2750N 08445W 5265 05515 0323 -021 -037 134016 017 004 000 00
230930 2750N 08443W 5353 05393 0322 -015 -035 134020 022 002 001 00
231000 2751N 08441W 5601 05026 0125 -002 -010 129025 028 011 000 00
231030 2752N 08439W 5731 04837 0135 +005 //// 130029 031 011 000 01
231100 2752N 08438W 5931 04566 0142 +019 //// 122031 032 015 001 05
231130 2753N 08436W 6157 04264 0149 +036 //// 110030 031 017 000 01
231200 2754N 08434W 6346 04019 0148 +053 +047 106029 031 018 000 03
231230 2755N 08432W 6642 03648 0176 +060 +057 097019 021 /// /// 03
231300 2755N 08430W 6937 03286 0169 +088 +059 096018 019 /// /// 03
231330 2756N 08428W 7309 02853 0176 +111 +076 085019 024 /// /// 03
231400 2758N 08427W 7704 02409 0180 +138 +033 054031 034 /// /// 03
231430 2800N 08429W 8042 02044 0180 +158 +005 051032 033 /// /// 03
231500 2801N 08431W 8418 01643 0165 +186 -004 057027 029 /// /// 03
$$
;



Oops yeah I was in the wrong column LOL. IMO this is an open trough.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
And Cassius Clay just threw a punch no one saw and she's down. We are breathlessly waiting 1,2,3,4,5,6,7,8,9,?
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I love the suttle English Linguistic dialects on a Friday.

Duee go on...
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Bonnie looks like crap, soooo.... next?
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Member Since: July 3, 2005 Posts: 423 Comments: 128240
Out of curiosity, what year did the NHC start labeling sytems as invests?
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lol the Recon is fly in too a open wave


well there gos all are $
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Quoting sammywammybamy:
What Remains to see is that a little thunderstorm or is it Convection Begining to Re-Fire?


I just noticed that... hmmmmm...
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at 8 it will be final advisory unless regeneration occurs then statements will be issued after that if needed
Member Since: July 15, 2006 Posts: 171 Comments: 53787
Quoting atmosweather:


Well they just turned around and climbed from 850mb...either they've found mechanical difficulty or they are scrubbing it because there's no longer a TC to fly into.
It appears that they turned around, but they still seem to be descending.
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Quoting Tazmanian:
round 1


90L bust

91L bust

92L bust

93L be comes Alex

94L bust

95L bust

96L be comes TD 2

97L be comes TS Bonnie

98L bust but may be upgrade at post season



we are still on round 1

99L still awaits us.
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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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