Bonnie weakens to a tropical depression
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
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1" maybe locally 2" if that.
Looks like there isn't really a surface feature there...I think it's a portion of the wave that moved through the islands 2 days ago that just degenerated...but the ULL and the associated mid/upper energy along with the upper divergence is helping convection fire down there. This must be watched later this weekend.
Exactly. Consistency one way or the other is all I would like to see.....far better than making a different call on every storm.
Don't shoot the experts.
u do know that the nhc has extremly better satelite loops then they provided for us the ones we link here isa joke lol trust me they know there stuff
Indeed, and there is some turning at the 500mb level in its northern portion north of the Dominican Republic, but any center of the disturbance may ultimately materialize farther south.
When did the recon find the west wind?
Or this?
its under a gray circle from the nhc
Yeah the better area for low pressure development is south and the better upper level environment is south too.
Experts? No. Experts are the ones working at NHC and other Meteorlogy offices that have degrees in meteorology and PHD and stuff.... I probably have just as much experience as Levi Does... Im just relatively new to posting comments on the blog and I dont blog here so people just dont know that yet
Possible home-grown mischief may have to be watched for off the SE coast or near Bermuda late next week, but the following week may see a more likely situation for home brew. The wave near Hispaniola will also have to be monitored on its way west, but is not currently an immediate threat.
True enough...
but with more and more information, we are able to see more and more of the pros AND the cons.
Bound to make the job more and more hard to do accurately, I would think.
What the WRF model has shown. Tracks it to the Yucatan.
Edit: It shows it near the Yucatan Peninsula by sometime on Monday.
Consistency has been in very short supply so far this season.
The last pass they did. But they also found the low weakening... regardless. this is a 30-35 mph td
84.3 °F
Clear
Humidity: 77%
Dew Point: 76 °F
Wind: 0.0 mph
Wind Gust: 1.0 mph
Pressure: 29.91 in (Rising)
Heat Index: 94 °F
Levi knows quite a lot, and if you are dissing Levi, you are dissing StormW and Patrap.
"la..La..La..
Technology tends to make things even more inconclusive ... it happens in cricket too! lol
;;;Dominican Republic;;;;;;;;;
Not one you want to listen to. Very trollish and usually horribly wrong.
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..
US-Cuba Hurricane Conference NOLA
Posted by: Patrap, 12:17 PM CST on November 24, 2009
Yesterday I was in attendance here in New Orleans for the US-Cuban Hurricane Conference.
It was a great day of sharing from folks who have been in many a fray, from General Russell Honore, to NHC Forecaster Lixion Avila, and many more..
I'm far from the best on this site.
That is what I am seeing as well.
No west winds at all right now (or recently)
I know that they are the professionals but i'd just like to see a little more consistency so that we can get a proper sense of the overall activity at the end of the year.
Depending on who you ask we could have anywhere from 2 to 5 named storms so far ...
I don't really care if this gets me a 24-hr ban but I'm sticking up for those who are knowledgeable AND who have very welcoming and positive attitudes here. You have zero basis on commenting the way you do towards Levi, and if you really think that you have as much meterological knowledge as Levi and the other GREAT experts here, then you're likely mistaken...but it's nothing compared to the way they ACT on this blog...respectful, informational, answer every question. It's a total disgrace how you can hide behind a screenname and take unnecessary shots at posters that make this blog great.
That's the only think I will say on the subject.
):):):)
For sure....it was a solid TS coming into Florida. Just small, and not able to produce a bunch of convection to make its presence felt a whole ton.
I respect you for admitting that... most of us commenters are " far from the best" on this site.
What tropical cyclone?
levi stormw cchc mh09 have all been great ty i agree
No... not mistaken... Levi is a good forecaster... he has good opinions... and ultimately... seems to be a good guy... but all I'm gonna say is this... We all have our opinions.. we are all entitled to our own opinion... we are dealing with a huge topic here... meteorology.... theres gonna be debate... but I dont wanna be belittled here just because Im new to commenting on the blog... Its ridiculous.
Models are developing a CV system and a system off the east coast in a week or two.
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