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: 1361 - 1311

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

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
1360. pottery
Quoting ElConando:


There are professional mets that come on the site from time to time. They could show up more often but it can be a zoo in here. I wonder if the same thing would happen in a blog talking about microscopes.

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?
Member Since: Posts: Comments:
1359. angiest
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.


Tampa missed it in 2004 by a degree or two change in Charley's course?
Member Since: Posts: Comments:
1358. angiest
Quoting texascoastres:
atmos and angiest also figure they dont want to take any chances and be caught up like Nagel and Blanco were. extremely bad so alittle planning goes a long way. I completely agree with you both.


I have a hard time faulting people behaving responsibly. Yeah, this time it looks like it was more of an exercise. Next time it may not be.
Member Since: Posts: Comments:
1357. Levi32
Quoting cntrclckwiseSpenn:


With that map you showed..do you feel the gulf coast is more under the gun this year than in years past? I know in Tampa, the attitude is pretty ignorant here that a major hurricane will hit.


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.
Member Since: Posts: Comments:
1356. KEEPEROFTHEGATE (Mod)
Member Since: Posts: Comments:
1355. xcool
Member Since: Posts: Comments:
Are the Hurricane Hunters still out there? havent heard about em in a while
Member Since: July 12, 2008 Posts: 11 Comments: 422
Takes 3 days to get some of the spill cleanup vessels out of harms way according to USCG. Keeping this in mind and the fact that you have plenty of locals and local governments also in harms way helping with the spill, calling SOE was a MUST. I don't always agree with LA govt, but we will likely be calling SOEs early and often this year regardless of whether a storm gets torn up.
Member Since: Posts: Comments:
atmos and angiest also figure they dont want to take any chances and be caught up like Nagel and Blanco were. extremely bad so alittle planning goes a long way. I completely agree with you both.
Member Since: Posts: Comments:
Bonnie increasing in areal coverage. Not much yet.

Member Since: Posts: Comments:
Quoting wfyweather:


Dissing Levi? No. I just think you guys praise him like he is the all mighty of the blog when in reality... he isn't. I know he has forecasting skills.... but no more than a lot of people here..

We praise Levi,StormW,456,Drak and other ones because they really know what there talking about among some folks on here that act like they do. And you little quote "he isn't" you must not know these good folks that take time out of there day to help us out and give there forecast and opinions and put things to where we understand it. So praising them doesn't hurt, it shows them we care what They have to say. So just sit back and you may learn something, if ya don't get POOFED first.
So does anyone think Mobile,Ala will feel anything out of this TD? I know it's nothing to really worry about just wondering.
Sheri
Member Since: Posts: Comments:
Quoting wfyweather:


Well given how things have gone so far this year and with Bonnie I dont expect it to sustain itself.. I think it will continue to fire and refire through landfall


As long as the LLC can avoid dissipation yes it will keep trying...it would be impressive if she can keep any of it near the center with the strong SE-erlies aloft.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting Patrap:
Nitey,,

off to do a Lil Road trip in the am.

For a Entry here soon.

ANTIQUES ROADSHOW event in Biloxi



UPDATE: 7/23/10 2:00 PM ET

Ticket Holders:
This Saturday's ANTIQUES ROADSHOW event in Biloxi will proceed as scheduled and will not be affected by the Tropical Storm Bonnie predictions.


EVENT LOCATION

Saturday, July 24, 2010

Mississippi Coast Convention Center
2350 Beach Boulevard
Biloxi, MS 39531

ANTIQUES ROADSHOW will be located in Exhibit Halls E1-E4.
Have fun Pat...and good luck. Hopefully they'll find a treasure.
.
.
I've gone to hundreds of those shows...on the other side of the counter. I'm the guy that tels you what your stuff is worth. One picture and a description is usually good enough.
Member Since: Posts: Comments:
1347. angiest
Quoting angiest:


I swear I've seen something similar from them this year. Maybe they talked about dew point 2 a few weeks ago.


ack, it's not the real discussion, its WU that is doing that. If you view the original text is says TD BONNIE. So I wonder why WU is expanded TD to dew point.
Member Since: Posts: Comments:
Quoting atmosweather:


Ernesto was a very very lucky break for FL. It took the exact worst path in terms of land interaction. That storm had the chance to be a major hurricane if things had have been just a little bit different.


Yeah some of the first tracks had it going WNW into Gulf. Once it was clear it was heading to Fla. It was forecast that it would landfall as a Cat 1. It came off Cuba as a 40mph TS then it was bumped to 45 when I assume they found winds of that in recon and then it just never intensified was just to disorganized to do so. Lucky break with all that, a Cat 1 on its path could have done a number on the area. Esp with all the tarped roofs around S Fla from Wilma a year earlier.
Member Since: Posts: Comments:
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!
Member Since: Posts: Comments:
1344. angiest
Quoting Levi32:


ROFL! I love those guys! For some reason the forecast discussions Homelesswanderer is always showing me out of Houston always have something great in there. I should look them up more often when there's something in the gulf.


I swear I've seen something similar from them this year. Maybe they talked about dew point 2 a few weeks ago.
Member Since: Posts: Comments:
Quoting Levi32:
The eastern Atlantic has indeed been invaded by some dry air this month, and the relative humidity anomalies for the month so far show that, but notice the moist anomalies west of 50W, with abnormal amounts of moisture across the entire SW Atlantic basin. This speaks volumes about where storms will tend to wind up this season, closer to home and farther west, where many landfalls are possible. It may not be the best setup for extreme numbers like 2005, but it is certainly a dangerous setup for historic impact on the United States and Caribbean countries.

Relative Humidity Anomalies for July 1st-July 20th:



With that map you showed..do you feel the gulf coast is more under the gun this year than in years past? I know in Tampa, the attitude is pretty ignorant here that a major hurricane will hit.
Member Since: Posts: Comments:
Quoting angiest:


It probably sounds strange for LA to declare with a storm east of Florida, but the decision was probably in part based on the speed of the storm. They declared about three days before forecast landfall, right? Seems prudent, given the uncertainty in forecast intensity and the special needs of their coast right now. If it had been moving half the speed, they probably would have waited.


I don't really have a problem with the declaration...3 days out, still a lot of uncertainty at that point, spill circumstances...they did what they had to do in the situation. In the end it will look strange but they made the right call.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
1341. angiest
1337 was supposed to be in reply to 1332, must have clicked the wrong one by mistake.
Member Since: Posts: Comments:
1340. Levi32
Quoting angiest:
A puzzler from the Houston forecast discussion:

Dew point Bonnie has moved into the Gulf but may have a hard time re-
strengthening. Still see minimal if any impacts for southeast Texas from
Bonnie at this time.


ROFL! I love those guys! For some reason the forecast discussions Homelesswanderer is always showing me out of Houston always have something great in there. I should look them up more often when there's something in the gulf.
Member Since: Posts: Comments:
Quoting atmosweather:


Trying its best but with conditions still hostile I'd be surprised if anything will be sustained. We will see.


Well given how things have gone so far this year and with Bonnie I dont expect it to sustain itself.. I think it will continue to fire and refire through landfall
Member Since: July 12, 2008 Posts: 11 Comments: 422
Bonnie slows amd begins to regenerate over warm, open waters!

Member Since: Posts: Comments:
1337. angiest
Quoting atmosweather:


Trying its best but with conditions still hostile I'd be surprised if anything will be sustained. We will see.


It probably sounds strange for LA to declare with a storm east of Florida, but the decision was probably in part based on the speed of the storm. They declared about three days before forecast landfall, right? Seems prudent, given the uncertainty in forecast intensity and the special needs of their coast right now. If it had been moving half the speed, they probably would have waited.
Member Since: Posts: Comments:
1336. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128875
THE CARIBBEAN SEA...
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO LINGER OVER THE
NORTHERN CARIBBEAN AND INLAND PORTIONS OF THE GREATER ANTILLES
NORTH OF 14N BETWEEN 64W AND 80W. THIS GROUP OF ISLANDS HAVE
ALREADY RECEIVED CONSIDERABLE AMOUNTS OF RAINFALL FROM WHAT IS
NOW TROPICAL DEPRESSION BONNIE. THE CONTINUATION OF RAINFALL
ACROSS THESE AREAS INCREASES THE THREAT OF FLOODING AND
POTENTIAL MUDSLIDES IN AREAS OF HIGH SATURATED TERRAIN. BROAD
CYCLONIC CIRCULATION ALOFT AROUND AN UPPER LEVEL LOW SPINNING
NORTH OF THE CARIBBEAN SEA NEAR 20N68W IS PRODUCING ALL THIS
WEATHER OVER THIS REGION. DRY AIR INTRUSION FROM THE NORTH
CENTRAL ATLANTIC IS FURTHER MAINTAINING THE UPPER LOW AND
ENHANCING THE CONVECTION GENERATED BY IT. EXPECT SHOWERS AND
THUNDERSTORMS TO CONTINUE OVER THE MENTIONED AREA AS THE UPPER
LEVEL LOW MOVES SW TOWARDS THE SE BAHAMAS. A TROPICAL WAVE IS
JUST EAST OF THE LESSER ANTILLES GENERATING ISOLATED SHOWERS AND
POSSIBLE THUNDERSTORMS OVER THE FAR EASTERN CARIBBEAN EAST OF
63W.
TWD description of features North of Dominican
Republic that several people have asked about
Member Since: Posts: Comments:
1334. Levi32
The eastern Atlantic has indeed been invaded by some dry air this month, and the relative humidity anomalies for the month so far show that, but notice the moist anomalies west of 50W, with abnormal amounts of moisture across the entire SW Atlantic basin. This speaks volumes about where storms will tend to wind up this season, closer to home and farther west, where many landfalls are possible. It may not be the best setup for extreme numbers like 2005, but it is certainly a dangerous setup for potentially historic impact on the United States and Caribbean countries.

Relative Humidity Anomalies for July 1st-July 20th:

Member Since: Posts: Comments:
Quoting jlp09550:


Jumps in the middle a bit, oops.. but anyways, looks like Bonnie is trying to fire off some more convection?


Trying its best but with conditions still hostile I'd be surprised if anything will be sustained. We will see.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Its all about safety and protection. Declaring a SOE doesnt do any thing except expedite the paperwork for after the storm if needed. If he hadn't done it, then he would be critized for not doing and not caring about the people of La. Always, always better to be proactive and prepared than caught with your pants down!
Member Since: Posts: Comments:
1331. centex
Quoting Levi32:


I'm far from the best on this site.
I've dissed you but think you are in top 10. I'm out of top 50 and just one who reads JM post, NHC post, and checks sat images and wind images before I post. Wish more did what I do and not in any way want to discourage the type/quality of effort you do. Sorry if I found a point to disagree, that is the only time I bother to post; When NHC or top bloggers do not consider something I tend to make post which may look to be offensive.. Keep it up and don't take my comments too seriously.
Member Since: Posts: Comments:
1330. Patrap
Nitey,,

off to do a Lil Road trip in the am.

For a Entry here soon.

ANTIQUES ROADSHOW event in Biloxi



UPDATE: 7/23/10 2:00 PM ET

Ticket Holders:
This Saturday's ANTIQUES ROADSHOW event in Biloxi will proceed as scheduled and will not be affected by the Tropical Storm Bonnie predictions.


EVENT LOCATION

Saturday, July 24, 2010

Mississippi Coast Convention Center
2350 Beach Boulevard
Biloxi, MS 39531

ANTIQUES ROADSHOW will be located in Exhibit Halls E1-E4.
Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting jlp09550:


Jumps in the middle a bit, oops.. but anyways, looks like Bonnie is trying to fire off some more convection?


Yup and on the west side of the center... like I said earlier... the next two hours or so will reallllly tell us a lot... And if this trend continues this may be able to maintain itself
Member Since: July 12, 2008 Posts: 11 Comments: 422
Quoting ElConando:
I don't think I've had over 40mph sustained in my area by a TC since Wilma brought over 90mph winds here the gusts were prob 110-120. Not that I'd like to see it again anytime soon.


its been 5 years were overdue remmember it only takes one
Member Since: Posts: Comments:
Bonnie isn't impressive... but it is still holding on to its 30-35 mph td status barely... I'm starting to doubt this will become a ts again.. but a td through landfall is most likely imho
Member Since: July 12, 2008 Posts: 11 Comments: 422
1326. Patrap
3 crow recipes
Member Since: July 3, 2005 Posts: 426 Comments: 128875
1325. angiest
Quoting atmosweather:


LMAO!


Now, was that some bizarre technology mistake (voice recognition changed depression to dew point, or a weird autocorrection error) or was the forecaster letting slip his/her impression of the system. :)
Member Since: Posts: Comments:
1324. gator23
Quoting chrisdscane:


is stormw a legit met

yes, he has no degree in it but he is a met for the coast guard and has been for years.
Member Since: Posts: Comments:


Jumps in the middle a bit, oops.. but anyways, looks like Bonnie is trying to fire off some more convection?
Member Since: Posts: Comments:
I don't think I've had over 40mph sustained in my area by a TC since Wilma brought over 90mph winds here the gusts were prob 110-120. Not that I'd like to see it again anytime soon.
Member Since: Posts: Comments:
Quoting ElConando:


There are professional mets that come on the site from time to time. They could show up more often but it can be a zoo in here. I wonder if the same thing would happen in a blog talking about microscopes.


is stormw a legit met
Member Since: Posts: Comments:
So far this year... I'm not impressed.... Nothing except Alex has really been able to sustaine itself as even a tropical wave.... Im starting to think 14-17 named storms is a better bet than my original forecast of 19-21
Member Since: July 12, 2008 Posts: 11 Comments: 422
1319. gator23
Quoting wfyweather:


It was stupid for Jindal to declare it in the first place... but since we are already in it I think they will hold it in place.

y not, its all about money anyway
Member Since: Posts: Comments:
1318. Patrap
..We're gonna need a Bigger entry..
in da morn"


Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting angiest:
A puzzler from the Houston forecast discussion:

Dew point Bonnie has moved into the Gulf but may have a hard time re-
strengthening. Still see minimal if any impacts for southeast Texas from
Bonnie at this time.


LMAO!
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting Levi32:


I don't know, but it was funny for them to even go there in the first place, and they certainly shouldn't be now.


It was stupid for Jindal to declare it in the first place... but since we are already in it I think they will hold it in place.
Member Since: July 12, 2008 Posts: 11 Comments: 422
i remmeber the good old days of this blog
Member Since: Posts: Comments:
Quoting Levi32:


I'm far from the best on this site.


There are professional mets that come on the site from time to time. They could show up more often but it can be a zoo in here. I wonder if the same thing would happen in a blog talking about microscopes.
Member Since: Posts: Comments:
1313. gator23
Quoting Levi32:


I don't know, but it was funny for them to even go there in the first place, and they certainly shouldn't be now.

I said that yesterday and Pat flipped out on me
Member Since: Posts: Comments:
Quoting ElConando:
Bonnie did give me more winds then Ernesto ever did. Give it that.


Ernesto was a very very lucky break for FL. It took the exact worst path in terms of land interaction. That storm had the chance to be a major hurricane if things had have been just a little bit different.
Member Since: September 24, 2005 Posts: 33 Comments: 9265

Viewing: 1361 - 1311

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.

Local Weather

Mostly Cloudy
46 °F
Mostly Cloudy