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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(Excerpt)
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.
Hey! Been a lurker since 2005 and this is my first post. I've very much enjoyed learning about tropical systems, tracking storms and getting to know some terminology.
I grew up sailing on Lake Winnipeg (short seasons...grr) and now keep a boat down in the St. Pete Beach area and although we summer up here, I keep a very watchful eye (some might say obsessive) on any tropical activity.
I liked the M. Jackson comment...just wondering if you've had any direct experience with Lake Winnipeg.
btw, Storm's, Levi's and a number more post excellent commentary. Learning lots!
Best regards.
G'night Storm!
Thanx..
We're going to the Antiques Road Show in Miss,Biloxi, in the am.
Hopefully.
The Mayan were and are a Great People.
She gave much needed rain to Florida.
NEXRAD Radar
Tampa, Base Reflectivity 0.50 Degree Elevation Range 124 NMI
I think so. Still a good one to watch the interaction at the very least. Some ULL's are rumored to be a good thing for tropical cyclones. Most of the time-not, imo.
Can anybody name a cane that owed its existence to an ULL?
Muzzle Tony Hayward
Yup, currently researching the history of 3- 7+ at that depth in such a short time. If you move the bottom the top will follow. Just sayin, that is big and deep.
Absolutely correct. And as far as the response, here is a perfect example. Jimmy Buffet donated a boat specifically designed for wildlife rescue over a week ago. It is still sitting in a parking lot because "they" can't figure out how to register and license it!! What???
Whats next...?
Wave Zilla ?
This is what I am keeping my eye on Pat. History ya know :)
http://en.wikipedia.org/wiki/Katla
"Following the 2010 Eyjafjallajkull eruptions, on 20 April 2010 Icelandic President lafur Grmsson said "the time for Katla to erupt is coming close ... we [Iceland] have prepared ... it is high time for European governments and airline authorities all over Europe and the world to start planning for the eventual Katla eruption"."
He actually attributed something to something else; for example: DRY AIR INTRUSION FROM THE NORTH CENTRAL ATLANTIC IS FURTHER MAINTAINING THE UPPER LOW AND ENHANCING THE CONVECTION GENERATED BY IT.
He's telling not only what is happening but why.
Maybe that came from the suggestion box they put on the NHC page.
What's with the vortex message they're only supposed to give those when there is a closed center.
1) she arrives in a weakened state, but still sucks heat out of the spill area waters, depriving future storms of this energy
2) does so at low tide
I've seen an ULL work it's way down to the surface and form a tropical system. Does that count?
Well that would kill the Hurricane season, but we'd all be gripped in a brutal cold winter season.. way worse than '09-10 winter.
But it seems there is no real sensitivity to the scope of the disaster they have caused, starting with the loss to their families of the eleven workers...
http://www.sat24.com
Extra-tropical transition cyclones?
000
URNT12 KNHC 240154
VORTEX DATA MESSAGE AL032010
A. 24/01:36:00Z
B. 26 deg 13 min N
083 deg 03 min W
C. 925 mb 782 m
D. 23 kt
E. 268 deg 1 nm
F. 051 deg 15 kt
G. 339 deg 5 nm
H. EXTRAP 1010 mb
I. 22 C / 764 m
J. 23 C / 765 m
K. 22 C / NA
L. NA
M. NA
N. 1345 / 9
O. 0.02 / 2 nm
P. AF305 0603A BONNIE OB 09
MAX OUTBOUND AND MAX FL WIND 44 KT N QUAD 01:47:00Z
SLP EXTRAP FROM 925 MB
MAX FL TEMP 23 C 089 / 6 NM FROM FL CNTR
;
Also to see the tropical waves
http://www.sat24.com/af
I think this is the site that Jason, the man who always puts the African Satellite pictures up uses.
My fav..
al La Claudette 09
I don't get it either. They even passed through and around the center twice in 15 minutes to find any W winds and still couldn't.
It seems there is a lot of "blame" to be shared around in this situation. I think a culture of "laissez faire" permeated the minerals/oil prospecting industry during the Bush years, so that people / companies / agencies were pretty much guided by whatever personal principles they had. If they didn't have any or many, they could easily be subverted by those who only cared about how much money they could make
They're dang bored....they shouldn't even be out there wasting money on a system that is no longer a tropical cyclone.
Probably, and of course you can't overlook this stuff that is happening too. There is much going on for sure :)
http://spaceweather.com/
"Sunspot 1089 has grown so large, it can now be seen without the aid of a solar telescope."
Ok, a winner! (on a technicality). Good to see you have not lost any brain cells over summer vacation from AggieLand, lil.
Time: 01:51:00Z
Coordinates: 26.9667N 83.2667W
Acft. Static Air Press: 924.8 mb (~ 27.31 inHg)
Acft. Geopotential Hgt: 809 meters (~ 2,654 feet)
Extrap. Sfc. Press: 1014.3 mb (~ 29.95 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 93° at 36 knots (From the E at ~ 41.4 mph)
Air Temp: 20.0°C* (~ 68.0°F*)
Dew Pt: ////°C* (~ °F*)
Peak (10s) Flt. Lvl. Wind: 38 knots (~ 43.7 mph)
SFMR Peak (10s) Sfc. Wind: 35 knots (~ 40.2 mph)
I know, I saw that an SUV fell into a sinkhole!
Coordinates: 26.4667N 83.1167W
Acft. Static Air Press: 925.0 mb (~ 27.32 inHg)
Acft. Geopotential Hgt: 784 meters (~ 2,572 feet)
Extrap. Sfc. Press: 1011.1 mb (~ 29.86 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 91° at 34 knots (From the E at ~ 39.1 mph)
Air Temp: 21.9°C* (~ 71.4°F*)
Dew Pt: ////°C* (~ °F*)
Peak (10s) Flt. Lvl. Wind: 38 knots (~ 43.7 mph)
SFMR Peak (10s) Sfc. Wind: 36 knots (~ 41.4 mph)
SFMR Rain Rate: 2 mm/hr (~ 0.08 in/hr)
Viewing: 951 - 1001
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