Tropical Depression Three forms

By: Dr. Jeff Masters , 3:42 PM GMT on July 22, 2010

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Tropical Depression Three has formed over the Bahama Islands, and appears poised to become Tropical Storm Bonnie later today. Satellite images of TD 3 show a modest area of heavy thunderstorms that have slowly increased in intensity and areal coverage this morning. The surface circulation center is exposed to view, thanks to strong upper-level winds out of the southwest that are creating about 20 knots of wind shear. This wind shear is due to the counter-clockwise circulation of air around a large upper-level low pressure system over Florida that is moving west at about the same speed TD 3 is. Water vapor satellite loops show a large area of dry air is associated with the upper-level low pressure system, and this dry air is hindering development of TD 3. The storm is attempting to wrap a curved band of clouds around its center, on its west side. If TD 3 is able to do this, the center will be protected from shear and dry air, and more significant strengthening can occur. Surface observations in the Bahamas and several nearby ships have shown top winds in TD 3 of up to 35 mph, so the storm is close to the 40 mph winds needed to be classified as a tropical storm.


Figure 1. Water vapor satellite image showing dry air (brown colors) associated with the upper-level low over Florida. Image credit: NOAA/NESDIS.

Track Forecast for TD 3
The storm is in a fairly straightforward steering current environment, and TD 3 should progress steadily to the west to west-northwest through Saturday. This will bring the storm ashore over the Florida Keys or South Florida on Friday, and into the Gulf of Mexico on Saturday. The latest set of model runs from 2am EDT (6Z) had the advantage of having data from a flight of the NOAA jet last night, so we have higher confidence than usual in the track of TD 3 over the next two days. The location of TD 3's final landfall along the Gulf of Mexico coast has the usual uncertainties for 3 - 4 days, with the various models calling for landfall somewhere between the upper Texas coast and the Florida Panhandle coast. Given the uncertainties, the move halt operations in the Deepwater Horizon blowout recovery effort are probably wise.

Intensity Forecast for TD 3
The primary detriment to development of TD 3 for the next three days will be the presence of the large upper-level low to its west. As long as this low remains in its present location, relative to TD 3, it will bring wind shear of about 20 knots and dry air into the storm. This will limit the intensification potential of TD 3 to no more than about 10 - 15 mph per day. If the upper-level low slow down a bit, relative to TD 3, more shear will affect the storm, potentially weakening it. Conversely, if the upper-level low picks up speed and pulls away from TD 3, the storm may be able to intensify at a faster rate. None of the computer models is calling for that to happen, but it would not take much of an additional separation between TD 3 and the upper level low to substantially reduce shear and allow TD 3 to intensify into a hurricane on Saturday. I put the odds of TD 3 making it to hurricane strength in the Gulf of Mexico at 20%.

98L
An area of disturbed weather (98L) has developed in the Gulf of Mexico's Bay of Campeche. This system is under a low amount of shear, 5 - 10 knots, and may barely have enough time to organize into a tropical depression before making landfall along the Mexican coast a few hundred miles south of the Texas border on Friday.

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 between 3 - 4 pm, when the Hurricane Hunters will be in the storm. I'll also speculate on the possible impact the storm will have on the oil spill region.

Jeff Masters

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821. swlavp
6:21 PM GMT on July 22, 2010
Quoting claire4385:
Lets all of us in the Acadiana area get together the nite before for a drink-casting party LOL.


LOL Sounds Good!!!
Member Since: June 16, 2010 Posts: 0 Comments: 117
820. WeatherNerdPR
6:21 PM GMT on July 22, 2010
Quoting Joanie38:
LOL! The funny thing is...My MOTHER'S name is Bonnie LOL!

LOL
Member Since: July 7, 2010 Posts: 0 Comments: 5690
819. LouisianaWoman
6:21 PM GMT on July 22, 2010
Erath, huh? Delcambre here!
Member Since: August 10, 2009 Posts: 0 Comments: 64
818. Patrap
6:21 PM GMT on July 22, 2010
StormW is right. Watch the Storm for now as we can by radar, Miami,Floater and Sat.

Its not gonna sneak up and Bite anyone but we should all be wary of the Potential here.

Intensity is the Lesser Known side of the Equation always.

Preparation is a Good Idea for anyone who feels they need to .

Its always easy to Plan and do Now than to be stressed later and make bad decisions.
Member Since: July 3, 2005 Posts: 426 Comments: 128630
817. claire4385
6:20 PM GMT on July 22, 2010
Of course neon...we don't need ppl getting in accidents or DUI's. That might b kinda fun though. Or we could all get together and go find Jim Cantore :-D
Member Since: November 8, 2009 Posts: 0 Comments: 98
816. gumboyaya
6:20 PM GMT on July 22, 2010
Quoting StormW:


Have to see how strong it is when it gets close.
Ya could see some good precip..winds will depend on how large of a wind field there is.


Hi neighbors!

Thanks for the info StormW. I can handle the precip. My tolerance for wind is around Cat 1-Cat 2 and depending upon landfall a Cat 3. After that, I'm a gone pecan!
Member Since: August 27, 2008 Posts: 0 Comments: 2
815. cchsweatherman
6:20 PM GMT on July 22, 2010
Several full west winds have been found. That confirms the closed low. Seems like they're very near the center around 21.9N and 75.0W.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
814. twhcracker
6:20 PM GMT on July 22, 2010
Quoting Capnbilll:

and spam!


and run down the aisle of walmart with your ten loafs of bread and spam with your eyes wild rolled back in your head screeching "its a tropical storm! 40 mph! Oh the humanity!" knocking people out of the way at the register. thats how the people from the air force base act in their first storm. Theres not a loaf of bread in the entire county once it gets about 90 hours away.
Member Since: July 30, 2007 Posts: 6 Comments: 1448
813. stormhunter23
6:20 PM GMT on July 22, 2010
Did anyone notice 98L?
Looking way better than TD 3 /TS Bonnie


See the difference?


Member Since: July 5, 2010 Posts: 0 Comments: 31
812. neonlazer
6:19 PM GMT on July 22, 2010
Quoting Seamule1:
startin to wrap up and explode....!!!!

TD three cat 3 before the key
Doomcaster...Did you mean for that to rhyme?
Member Since: July 5, 2008 Posts: 0 Comments: 254
811. jlp09550
6:19 PM GMT on July 22, 2010
Abbeville, LA here, well, south of Abbeville. Near the coastline. If you know your tiny areas in SC LA, then I'm in Intracoastal City. :)
Member Since: February 21, 2008 Posts: 1 Comments: 340
810. TankHead93
6:19 PM GMT on July 22, 2010
It appears from satellite imagery TD3 is strengthning and on the verge of becoming TS Bonnie. It also appears from TD3 satellite presentation that shear is weakening significantly around it. Is the later true?
809. MiamiHurricanes09
6:19 PM GMT on July 22, 2010
Quoting cchsweatherman:


I would say so. Got two nice feeder band features developing to the north and from the south. Some spiral banding is becoming evident in recent images.
Indicative of a strengthening system.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
808. kingzfan104
6:19 PM GMT on July 22, 2010
806. Seamule1
6:19 PM GMT on July 22, 2010
startin to wrap up and explode....!!!!

TD three cat 3 before the key
Member Since: June 30, 2010 Posts: 0 Comments: 27
805. Joanie38
6:19 PM GMT on July 22, 2010
LOL! The funny thing is...My MOTHER'S name is Bonnie LOL!
Member Since: June 16, 2008 Posts: 0 Comments: 507
804. sgvalenti
6:19 PM GMT on July 22, 2010



Eric Berger "Science guy" is having a live chat on the Houston ChronLink
Member Since: September 21, 2002 Posts: 0 Comments: 45
803. Drakoen
6:19 PM GMT on July 22, 2010
It will be interesting to see what the HH's find in the NE quadrant
Member Since: October 28, 2006 Posts: 57 Comments: 30561
802. cchsweatherman
6:18 PM GMT on July 22, 2010
Quoting jlp09550:


Attempting to wrap around?


I would say so. Got two nice feeder band features developing to the north and from the south. Some spiral banding is becoming evident in recent images.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
801. CybrTeddy
6:18 PM GMT on July 22, 2010
Recon found some pretty convincing TS winds.. what do you all think?
Member Since: July 8, 2005 Posts: 259 Comments: 24161
800. unf97
Quoting StormW:
Nice obs Pat...

Folks, let's not freak about the track. Close obs of visible satellite loop imagery indicates that while the center may have shifted somewhat, even if it were to travel more NW than thought, the farthest north it would possibly make it could be Andros Island, before being turned more toward left. So, for a short, it could be a little further right of track, but overall, I feel NHC has a good track at the moment. (36-48 hours)

The ridge is noted building in as we speak.


Thanks Storm for your astute analysis! It is very much appreciated!!!
Member Since: Posts: Comments:
NEXRAD Radar
Miami, Velocity Azimuth Display Wind Profile Range 124 NMI

Note how the Gust are short and long in between too. As the Storm nears the wind and Heights will Increase as the Duration between gust will shorten.



Member Since: July 3, 2005 Posts: 426 Comments: 128630
Quoting 34chip:
Guys this looks like a Florida Keys Storm not South Florida. South Florida will only get the affects CHILL OUT!!!


I thought someone mentioned that the heavy weather is going to be north of the storm. If so, doesn't that mean that SFL (Miami and maybe Broward) would get the brunt of the weather if it tracks thru the Keys or just south of?
Member Since: Posts: Comments:
Quoting claire4385:
Lets all of us in the Acadiana area get together the nite before for a drink-casting party LOL.
Lol, As long as there is root beer :P
Member Since: July 5, 2008 Posts: 0 Comments: 254
Quoting sarahjola:
Quoting MiamiHurricanes09:
The center isn't reforming, it however is relocating
where to?:)
Under the deepest convection, signs of a strengthening system.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
SFMR already getting TS force winds. Google Earth HDOB messages back up and running.
Member Since: Posts: Comments:
Quoting neonlazer:
So we got Slidell, Baton Rouge, Lafayette, Lake Charles...i think one of us might get hit..hope its me!(coming from a nuthead who gets excited over storms..and another friend whose anxious to have a hurricane party..)


Sulphur, LA here
Member Since: Posts: Comments:
Quoting Patrap:
TD-3 Outermost Western Bands of Rain now on Long range..Miami.

NEXRAD Radar
Miami, Base Reflectivity 0.50 Degree Elevation Range 248 NMI



I see.
Member Since: Posts: Comments:
Quoting Patrap:
TD-3 Outermost Western Bands of Rain now on Long range..Miami.

NEXRAD Radar
Miami, Base Reflectivity 0.50 Degree Elevation Range 248 NMI



Will be fun to watch the storm come into view and move either past or through South Florida. Perfect radar view to watch in the coming hours.
Member Since: April 14, 2007 Posts: 8 Comments: 5169


Attempting to wrap around?
Member Since: February 21, 2008 Posts: 1 Comments: 340
Quoting StSimonsIslandGAGuy:



How'd you get the radar animation to slow down at the end?


I will slow the rate..
Member Since: July 3, 2005 Posts: 426 Comments: 128630
Lets all of us in the Acadiana area get together the nite before for a drink-casting party LOL.
Member Since: November 8, 2009 Posts: 0 Comments: 98
Quoting ElConando:


Seen you do this a few times. What for?


Show the Local winds offshore near the Miamai Radar Site..
The Pattern is one to watch the next few days as the Cyclone passes .The Gust Durations and Wind Heights we can observe.

Each Cyclone has its own particular cycle.
Member Since: July 3, 2005 Posts: 426 Comments: 128630
Quoting MiamiHurricanes09:
The center isn't reforming, it however is relocating
where to?:)
Member Since: Posts: Comments:
Quoting Patrap:
TD-3 Outermost Western Bands of Rain now on Long range..Miami.

NEXRAD Radar
Miami, Base Reflectivity 0.50 Degree Elevation Range 248 NMI

Here it comes...
Member Since: September 2, 2009 Posts: 130 Comments: 21194
757.

Was that really necessary?
Member Since: Posts: Comments:
Quoting txsweetpea:



Hey Joanie... I believe we need to keep a close eye on this one..


Hey txsweetpea..yeah I think we may have to watch this one...I am watching it very closely....
Member Since: June 16, 2008 Posts: 0 Comments: 507
Baton Rouge here!
Member Since: Posts: Comments:
Quoting bourgeoisdude:
Hey, I'm long time lurker but a relative newbie. When you guys are talking about the wind speeds from recon, are we talking gusts or 1 minute sustained winds?


Depends on which observation is noted. There are:

Flight level 30 second
Flight level 10 second peak
SFMR 10 second average

I have never seen documentation on how they convert 10 second SFMR to 1 minute average. Guess you could just take 6 readings and average.
Member Since: Posts: Comments:
Lowest pressure found so far is 1008mb, in agreement with the 2PM advisory.

000
URNT15 KNHC 221811
AF306 02BBA INVEST HDOB 24 20100722
180230 2217N 07512W 9913 00148 0083 +236 +143 025019 021 027 004 00
180300 2216N 07511W 9912 00150 0084 +233 +142 015017 020 029 003 00
180330 2215N 07510W 9914 00148 0084 +235 +141 011017 018 027 003 00
180400 2213N 07509W 9914 00147 0084 +235 +141 002014 015 025 003 00
180430 2212N 07508W 9914 00147 0083 +235 +142 345014 015 026 002 00
180500 2210N 07507W 9914 00148 0084 +235 +144 340015 015 025 003 00
180530 2209N 07506W 9914 00147 0084 +235 +147 336014 015 026 003 00
180600 2207N 07505W 9914 00147 0084 +235 +151 338013 014 024 004 00
180630 2206N 07504W 9911 00152 0084 +235 +154 326012 013 022 003 00
180700 2205N 07503W 9913 00148 0083 +236 +157 320012 013 023 002 00
180730 2203N 07502W 9912 00149 0083 +240 +160 306011 012 022 002 00
180800 2202N 07501W 9915 00146 0083 +236 +162 303010 011 021 002 00
180830 2201N 07501W 9914 00149 0085 +238 +164 299010 010 021 003 00
180900 2159N 07500W 9901 00161 0086 +239 +166 291010 010 021 001 00
180930 2158N 07459W 9910 00157 0089 +240 +167 279009 009 018 003 00
181000 2156N 07457W 9914 00155 0091 +241 +168 276009 010 021 002 00
181030 2154N 07456W 9911 00159 0093 +241 +170 272010 010 021 001 00
181100 2153N 07455W 9914 00158 0094 +242 +171 263011 012 023 001 00
181130 2151N 07454W 9915 00157 0095 +240 +173 271011 011 021 002 00
181200 2150N 07453W 9913 00159 0095 +243 +175 280011 011 016 005 00
$$
;
Member Since: September 2, 2009 Posts: 130 Comments: 21194

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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.