Bonnie weakens to a tropical depression

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

Share this Blog
6
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1411 - 1361

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45Blog Index

1411. angiest
Quoting cntrclckwiseSpenn:


well there are a number of storms that have gone upto the panhandle, or have hit towards ft myers as well though. Not all storms move east to west...some cane start-out in the SW carib or GOM.


By recurving storms I meant, in part, storms that were further south in the Caribbean that turned north and came in like Charley did. Storms moving west to east in the Gulf appear rather rare.
Member Since: Posts: Comments:
Quoting CosmicEvents:
Well, I'm not a trained aircraft spotter, but I've seen and heard enough commercial, private, and military planes. This one was different, and at the time the center area was about 50 miles away.
.
.
If they don't fly over land, then how do they get from here to there. I'm not saying a dropsonde landed on my yard.

They dont fly over land on missions...that is why their staging bases are on the water. By the way a HH is a WC-130 and is no different than any other C-130. They dont sound or look any different. Google WC-130 and C-130 and you will see they are exactly the same.
Member Since: Posts: Comments:
The HWRF had a crazy course north of Tampa for awhile. That was uncalled for because of climatology. It's possible to get storms there, but they have much more likely paths elsewhere.
Member Since: Posts: Comments:
Quoting cntrclckwiseSpenn:


Yes,and had Charley hit where I live (Bradenton) or even an hour north in Tampa, Charley would of been a cat. 5. It went from a cat 1 to cat 4 in 6 hours.....and i think it had something to do with a loop eddy.. Fortunately, what a front, or trough curved it towards port Charlotte harbor. unfortnate for them, but thankfully it was moving fairly quickly. I remember tampa people going to orlando thinking they were safe, and getting slammed inland.


It only needed probably an hour or two longer and it would have been a Category 5. It was already 150 mph at landfall...small but extremely intense central core, zero wind shear, much more instability in the atmosphere compared to normal (the abnormal southerly trough helped with that). That was a monster. Got sustained 85 mph winds here at my house and 2 gusts to 109 mph.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
1407. angiest
Quoting cirrocumulus:
Say it ain't so Joe! TD3 is getting stronger again.



Finally getting a good drink of warm GOM water. Soon it will be high octane water.
Member Since: Posts: Comments:
1406. Levi32
Quoting HaboobsRsweet:


They dont fly over land...you sure it was a HH? There are many other bases with C-130s.


They did earlier....could see it on Google Earth. They will fly over land when necessary. They weren't about to go all the way around the Florida Peninsula this morning just to get to Bonnie.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting CosmicEvents:
I had one fly overhead at low altitude early this morning. First time I've seen one. Very cool. My dog and I both stared at it.



I see them fly in and out of Keesler frequently. There's a small bar & grill on the beach there (one of the very few back, post Katrina) called Snapper's. If you're on the beachside deck, you can often catch one coming in for landing - they literally look as if they're going to fly right into the building. AMAZING! Big fan of the HH's!
Member Since: Posts: Comments:
Quoting angiest:


Well, think about it. Most storms are going to be moving from the east to west, so a strike from a Gulf storm on the west coast of Florida is somewhat unlikely. Much more likely for them to get a recurving storm from the South or one that crossed Florida and then recurves and hits again. I believe such a thing happened in the 60s, Donna, perhaps?


well there are a number of storms that have gone upto the panhandle, or have hit towards ft myers as well though. Not all storms move east to west...some cane start-out in the SW carib or GOM.
Member Since: Posts: Comments:



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Say it ain't so Joe! TD3 is getting stronger again.

Member Since: Posts: Comments:
Quoting CosmicEvents:
Well, I'm not a trained aircraft spotter, but I've seen and heard enough commercial, private, and military planes. This one was different, and at the time the center area was about 50 miles away.
.
.
If they don't fly over land, then how do they get from here to there. I'm not saying a dropsonde landed on my yard.


XD that would be cool if one did
Member Since: July 12, 2008 Posts: 11 Comments: 422
Quoting HaboobsRsweet:


They dont fly over land...you sure it was a HH? There are many other bases with C-130s.
Well, I'm not a trained aircraft spotter, but I've seen and heard enough commercial, private, and military planes. This one was different, and at the time the center area was about 50 miles away.
.
.
If they don't fly over land, then how do they get from here to there. I'm not saying a dropsonde landed on my yard.
Member Since: Posts: Comments:
Quoting Levi32:


Yeah they did get very lucky. That's exactly the kind of storm that can do it...coming over western Cuba from the southwest. It had the angle if it hadn't have curved in. I forget the numbers but I believe Tampa is almost as void of direct hits in the 20th and 21st century as the coast of Georgia is.


Yes,and had Charley hit where I live (Bradenton) or even an hour north in Tampa, Charley would of been a cat. 5. It went from a cat 1 to cat 4 in 6 hours.....and i think it had something to do with a loop eddy.. Fortunately, what a front, or trough curved it towards port Charlotte harbor. unfortnate for them, but thankfully it was moving fairly quickly. I remember tampa people going to orlando thinking they were safe, and getting slammed inland.
Member Since: Posts: Comments:
Quoting LightningCharmer:
Oh...Microscopes...Wrong blog...Sorry...Was looking for information on the latest planetary convergence, and its effect on my ex's mood swings...LOL

<--Survived a direct hit by Bonnie. I have to declare, I'm a Bonnie survivor.


I ate bon bons while watching Bonnie talking about Bonnie.
Member Since: Posts: Comments:
Quoting cntrclckwiseSpenn:



Yeah, I've always wondered why it is hard to hit the central coastline of Florida (Tampa area. Panhandle and southern Fl gets hit fairly frequently?????...but the last time a major hurricane hit here was 1920 I believe.


A lot of it is just pure luck...and also the shape of the peninsula...most storms that come from the S will either turn NE into extreme SW FL (Wilma/Charley) or just move N-ward into the panhandle. You need a strong fall-like trough to catch it at just the right time.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Thanks pcbsmokey. There was a burst of convective activity when TD3/Bonnie hit the 30 degree water SST. There is more precipitable water to the west of Bonnie because so much is training in from the south.
Member Since: Posts: Comments:
1394. Levi32
Quoting cntrclckwiseSpenn:



Yeah, I've always wondered why it is hard to hit the central coastline of Florida (Tampa area. Panhandle and southern Fl gets hit fairly frequently?????...but the last time a major hurricane hit here was 1920 I believe.


It's the shape of the coastline....SW Florida is facing SW and is easily hit by storms like Charley and Wilma. After you get to Tampa the coast switches to concave inward and heads northeast for a while, and if you have a storm coming out of the SSW, it can easily miss Tampa and head into the bight of Florida. The angle has to be so perfect....that's why they're hard to hit. The shape of the coastline is some of the same reason why Jacksonville, Florida and the Georgia coast are also so hard to hit.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting wfyweather:


I am in N.O for a Bonnie Intercept.. Lets hope I can survive this beast! Lol!
I believe, I was actually driving through the Cutler area when it made land fall. To be fair, I could have missed the e** **ll by a few minutes...LOL
Member Since: Posts: Comments:
1392. angiest
Quoting cntrclckwiseSpenn:



Yeah, I've always wondered why it is hard to hit the central coastline of Florida (Tampa area. Panhandle and southern Fl gets hit fairly frequently?????...but the last time a major hurricane hit here was 1920 I believe.


Well, think about it. Most storms are going to be moving from the east to west, so a strike from a Gulf storm on the west coast of Florida is somewhat unlikely. Much more likely for them to get a recurving storm from the South or one that crossed Florida and then recurves and hits again. I believe such a thing happened in the 60s, Donna, perhaps?
Member Since: Posts: Comments:
Quoting pottery:

And what have you got against microscopes?
Its people like you that give people like me a pain, always harping on about the relative merits of bi-focal or uni-focal microbe viewing apparatus.
For your information, the Journal of American Microscope Lookers-Through have all the knowledge and experience that you dont have, and are the Authority on the matter.
I have been a lurker on this blog for 57 years and never heard you say one decent thing about microscopes.
Very sad. Poof!

How's that?


RDSL that was EPIC! :)
Member Since: Posts: Comments:
1390. Speeky
Quoting wfyweather:


Luckily... it isnt a strong hurr and definitely isnt on track to become one


True, I am expected T.D. Bonnie to hit Louisana as a Tropical Storm with winds around 40 - 50 mph. I also expect rain amounts to be around 1 - 3 inches. Otherwise no severe threat for damage or flooding. However anything can happen in the gulf of mexico when the conditions are right.
Member Since: Posts: Comments:
1389. xcool
ha
Member Since: Posts: Comments:
1388. scott39
StormW said there would possibly be 2 small windows of oppurtunity for Bonnie to fire up some convection and gain a little strength before landfall. This may be the first.
Member Since: Posts: Comments:
Good night all! got to be up a 4am, working 5am til 10pm going to need this site tomorrow night at work to stay a wake
Member Since: Posts: Comments:
Quoting catastropheadjuster:


If I was Levi's mom I would be very proud of such a smart son, and proud of his disposition and manners. He has been raised right.
Sheri


Yeah He does have good manners. More so than I do.. Maybe I should work on that... Lol...

Sorry everyone.... I do need to work on that.
Member Since: July 12, 2008 Posts: 11 Comments: 422
Quoting cntrclckwiseSpenn:



Yeah, I've always wondered why it is hard to hit the central coastline of Florida (Tampa area. Panhandle and southern Fl gets hit fairly frequently?????...but the last time a major hurricane hit here was 1920 I believe.



I guess most systems a) don't have time to form once they hit cuba or b) get caught up in fronts that sweep/curve them south or take them north..or more west towards LA/Texas?
Member Since: Posts: Comments:
Quoting LightningCharmer:
Oh...Microscopes...Wrong blog...Sorry...Was looking for information on the latest planetary convergence, and its effect on my ex's mood swings...LOL

<--Survived a direct hit by Bonnie. I have to declare, I'm a Bonnie survivor.


I am in N.O for a Bonnie Intercept.. Lets hope I can survive this beast! Lol!
Member Since: July 12, 2008 Posts: 11 Comments: 422
GOM PW
Member Since: Posts: Comments:
Quoting Levi32:


Definitely. I wouldn't be surprised to see a year like 2008 impact-wise in the gulf which had 6 storms move through the gulf, and it could even be worse than that. We've already had 2 or 3 if you count TD 2. A couple of them will likely be majors, but we can hope to be lucky.

You know....no joke it's dang hard to hit Tampa directly with a hurricane. It really is. They will get one someday...impossible to say if it will be this year, but the month that they are most likely to get at least a direct impact from a major hurricane would be October, when storms are more likely to come into Florida from the southwest.



Yeah, I've always wondered why it is hard to hit the central coastline of Florida (Tampa area. Panhandle and southern Fl gets hit fairly frequently?????...but the last time a major hurricane hit here was 1920 I believe.
Member Since: Posts: Comments:
centex: It's embedded much more in moisture than it was. The ULL is also pulling in lots of moisture to it's own outside areas to the south and east and thus changing it's dynamics.
Member Since: Posts: Comments:
1380. pottery
Quoting LightningCharmer:
Oh...Microscopes...Wrong blog...Sorry...Was looking for information on the latest planetary convergence, and its effect on my ex's mood swings...LOL

<--Survived a direct hit by Bonnie. I have to declare, I'm a Bonnie survivor.

LOL
Member Since: Posts: Comments:
1379. bassis
Quoting pottery:

And what have you got against microscopes?
Its people like you that give people like me a pain, always harping on about the relative merits of bi-focal or uni-focal microbe viewing apparatus.
For your information, the Journal of American Microscope Lookers-Through have all the knowledge and experience that you dont have, and are the Authority on the matter.
I have been a lurker on this blog for 57 years and never heard you say one decent thing about microscopes.
Very sad. Poof!

How's that?


microscope caster!
Member Since: Posts: Comments:
Quoting Speeky:
Has anyone Noticed that Bonnie seems to be taking the same track as Hurricane Andrew?

If bonnie were a strong hurricane this would be bad news for New Orleans


Luckily... it isnt a strong hurr and definitely isnt on track to become one
Member Since: July 12, 2008 Posts: 11 Comments: 422
Quoting pottery:

And what have you got against microscopes?
Its people like you that give people like me a pain, always harping on about the relative merits of bi-focal or uni-focal microbe viewing apparatus.
For your information, the Journal of American Microscope Lookers-Through have all the knowledge and experience that you dont have, and are the Authority on the matter.
I have been a lurker on this blog for 57 years and never heard you say one decent thing about microscopes.
Very sad. Poof!

How's that?
Oh...Microscopes...Wrong blog...Sorry...Was looking for information on the latest planetary convergence, and its effect on my ex's mood swings...LOL

<--Survived a direct hit by Bonnie. I have to declare, I'm a Bonnie survivor.
Member Since: Posts: Comments:
Quoting CosmicEvents:
I had one fly overhead at low altitude early this morning. First time I've seen one. Very cool. My dog and I both stared at it.


They dont fly over land...you sure it was a HH? There are many other bases with C-130s.
Member Since: Posts: Comments:
Quoting angiest:


I was under the impression they never did recon over land, even in the US (Florida being a special case where it can make sense to do it).
Of course. They were on their way off-shore I'm sure. I guess. They were at under 5000 ft.
Member Since: Posts: Comments:
Channel 11 here in houston said it still has a chance of getting back to ts so monitor it. but the low over us was going to be pulling the gulf moisture in and provide us with more rain this weekend
Member Since: Posts: Comments:
1373. Levi32
Quoting angiest:


Tampa missed it in 2004 by a degree or two change in Charley's course?


Yeah they did get very lucky. That's exactly the kind of storm that can do it...coming over western Cuba from the southwest. It had the angle if it hadn't have curved in. I forget the numbers but I believe Tampa is almost as void of direct hits in the 20th and 21st century as the coast of Georgia is.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
1372. Speeky
Has anyone Noticed that Bonnie seems to be taking the same track as Hurricane Andrew?

If bonnie were a strong hurricane this would be bad news for New Orleans
Member Since: Posts: Comments:
Quoting CosmicEvents:
I had one fly overhead at low altitude early this morning. First time I've seen one. Very cool. My dog and I both stared at it.


Thats pretty sweet! :)
Member Since: July 12, 2008 Posts: 11 Comments: 422
1370. Levi32
Quoting RMM34667:
Levi.. I just LOVE your tropical tidbits, and while I watch them at work my co-workers will come look over my sholder (they think I'm studying weather stuff and such)..

But as long as there is something spining in the gulf (and I'm watching Pat's radars, and it is still spinning) I want the NHC on it.

You know the saying it easier to ask for forgiveness than to ask for permission?? Well I think it easier to keep something going then to resurrect it from the dead. And I personally don't give a hoot about playing by the book, cause nothing in this world is black and white.. There is a hell of alot of grey area in everything.

And one more thing.. If I was Levi's mother I would be so damn proud of him!! I for one LOVE hearing these young kids and their passion for my favorite subject!


Lol, well thank you :)

I do suppose it's true to be better safe than sorry, and with the oil situation I'm sure people will want to see advisories issued until they are sure it really is completely gone.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
1369. angiest
Quoting CosmicEvents:
I had one fly overhead at low altitude early this morning. First time I've seen one. Very cool. My dog and I both stared at it.


I was under the impression they never did recon over land, even in the US (Florida being a special case where it can make sense to do it).
Member Since: Posts: Comments:
Quoting atmosweather:


They're flying through the E side of the circulation right now. Top winds mostly unchanged.


Thanks so much.... so still a depression.. but honestly... it wont take much for this thing to go up 5 mph
Member Since: July 12, 2008 Posts: 11 Comments: 422
1367. xcool
hmm
Member Since: Posts: Comments:
Quoting wfyweather:
Are the Hurricane Hunters still out there? havent heard about em in a while
I had one fly overhead at low altitude early this morning. First time I've seen one. Very cool. My dog and I both stared at it.
Member Since: Posts: Comments:
The crazy ULL is so busy spinning it's actually starting to pull moisture in from the south and east now. Pretty soon it will be a lot less dry.
Member Since: Posts: Comments:
Quoting RMM34667:
Levi.. I just LOVE your tropical tidbits, and while I watch them at work my co-workers will come look over my sholder (they think I'm studying weather stuff and such)..

But as long as there is something spining in the gulf (and I'm watching Pat's radars, and it is still spinning) I want the NHC on it.

You know the saying it easier to ask for forgiveness than to ask for permission?? Well I think it easier to keep something going then to resurrect it from the dead. And I personally don't give a hoot about playing by the book, cause nothing in this world is black and white.. There is a hell of alot of grey area in everything.

And one more thing.. If I was Levi's mother I would be so damn proud of him!! I for one LOVE hearing these young kids and their passion for my favorite subject!


If I was Levi's mom I would be very proud of such a smart son, and proud of his disposition and manners. He has been raised right.
Sheri
Member Since: Posts: Comments:
1363. centex
Quoting cirrocumulus:
Bonnie increasing in areal coverage. Not much yet.

Maybe it'S a start of something.
Member Since: Posts: Comments:
Its continuing to fire up convection... I cant expect this trend to continue but if it does.... td Bonnie will be able to sustain itself and the forecast for it to become a TS is still plausible.
Member Since: July 12, 2008 Posts: 11 Comments: 422
Quoting wfyweather:
Are the Hurricane Hunters still out there? havent heard about em in a while


They're flying through the E side of the circulation right now. Top winds mostly unchanged.
Member Since: September 24, 2005 Posts: 33 Comments: 9265

Viewing: 1411 - 1361

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.