TD 3 growing more organized

By: Dr. Jeff Masters , 8:01 PM GMT on July 22, 2010

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Tropical Depression Three is steadily organizing, and appears poised to become a much stronger storm than was forecast. Water vapor satellite loops show that the upper level low to the west of TD 3 that has been bringing high levels of wind shear to the storm is now moving faster to the west than predicted. This faster motion has resulted in a reduction in wind shear over TD 3, to a moderate 10 knots. Satellite images of TD 3 show that the storm is taking advantage of the lower shear by developing several low-level spiral bands to the north and east of the center. However, the center of circulation is still exposed to view, and dry air is still getting injected into the core of the storm from the southwest. The storm's heavy thunderstorms have not increased in intensity this afternoon, and the amount of heavy thunderstorm activity near the core of the storm is still limited. TD 3 will need to build more intense thunderstorms near its center before significant intensification can occur. TD 3 is a small storm, and surface observations in the Bahamas do not show the circulation very well. An outer rain band of TD 3 is now visible on Miami long-range radar, and a flood watch has been issued for all of South Florida. The Hurricane Hunters are in the storm at present, and have found top surface winds of 35 - 40 mph.


Figure 1. Afternoon satellite image of TD 3.

Track Forecast for TD 3
The storm is in a straightforward steering current environment, and TD 3 should progress steadily to the west-northwest through Sunday. 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 8am EDT (12Z) foresee a track more to the north than the previous set of model runs. This increases the threat to the oil spill region, and I give a 40% chance that the oil spill region will see tropical storm force winds of 39 mph or higher this weekend. Oil recovery and relief well drilling operations should cease. If TD 3 makes a direct hit on the oil spill region as a tropical storm with 50 - 60 mph winds, it will likely drive a storm surge of 3 - 6 feet with high waves on top into the Louisiana marshlands, fouling a large area with oil. Oil would also penetrate into Lake Pontchartrain, which lies just two feet above sea level. However, the wave action of the storm will dilute the oil to some degree, which may limit the damage to the marshlands.

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 5 pm probabilities of various locations getting tropical storm force winds, 39 mph or higher:

Marathon 55%
Marco Island 43%
Miami 34%
New Orleans 33%
Galveston 13%

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. If the low remains in its present location, relative to TD 3, it will bring wind shear of about 10 knots to the storm. This will allow for steady intensification of perhaps 20 mph per day, and TD 3 could be a hurricane by Sunday at that pace. However, if the upper-level low slows down a bit, relative to TD 3, more shear and dry air will affect the storm, potentially weakening it. None of the computer models is calling for TD 3 to strengthen into a hurricane, but if the shear continues at 10 knots, I expect TD 3 will become a hurricane. My low-confidence intensity forecast gives TD 3 a 40% chance of becoming a hurricane. NHC is putting the odds of TD 3 being a hurricane at 2 pm Sunday at 15% with their 5pm advisory.

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 probably does not 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 in the morning. ABC World News Tonight will probably show a sound bite I did for them today, on their 6:30pm broadcast.

Jeff Masters

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Quoting Tazmanian:
1161. CaneWarning 11:02 PM GMT on July 22, 2010 Hide this comment.

Quoting KATRINABILOXIGIRL:
Local Met just said that it is now officially Tropical Storm Bonnie per the HH



Old news, and the center is de-coupled. RIP Bonnie. It's just a matter of time before this storm is RIP one way or another.



POOF


LOL Did Taz just poof me?
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1161. CaneWarning 11:02 PM GMT on July 22, 2010

decoupling doesnt automatically mean the system will die, there are a number of things that can happen from this point on

stop trying to get a reaction out of people
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Quoting RufusBaker:
I think Bonnie will reform farther to the north under that new blow of convection and central FL will get it


I sure hope you are right.
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1164. Levi32
Quoting Levi32:


Doubtful because in this kind of a situation the best environmental conditions and lowest surface pressures are to the south, not to the north. The NW path is the most favorable for intensification because of the upper low backing away, but the low-level steering flow will be trying to tug the low-level center westward. The mid-level center will eventually follow but for now the two are parting ways.


That might seem like a contradiction, but it's not. The best path for intensification is northwest because of the upper low backing WSW, and the mid-level center is getting pulled in that direction. However, the best environmental conditions for development of low pressure are southeast of Bonnie, and the low-level steering flow is keeping the surface center farther south than the mid-level center, and thus the decoupling is taking place.
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Quoting Patrap:
Gov Bobby Jindal issues a State of Emergency for Louisiana



Can we say over react?
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1162. Patrap


Tropical Video Update: Tropical Storm Bonnie near Bahamas

Posted on July 19, 2010 at 8:42 AM

Updated today at 5:35 PM

Tropical Storm Bonnie has formed near the Bahamas. Winds now are at 40 mph. Models have it moving through the Straits of Florida Friday and into the Gulf Saturday as a tropical storm.
Member Since: July 3, 2005 Posts: 421 Comments: 127559
i see that patrap, do you think its going to get sheared again?
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I think Bonnie will reform farther to the north under that new blow of convection and central FL will get it
Member Since: July 5, 2009 Posts: 0 Comments: 578
1158. Patrap
Gov Bobby Jindal issues a State of Emergency for Louisiana

Member Since: July 3, 2005 Posts: 421 Comments: 127559
1157. redUK
Quoting Levi32:


... The mid-level center will eventually follow but for now the two are parting ways.


And fast, the LLC headed just north of due west and the MLC headed NW
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Quoting CaneWarning:
RIP Bonnie.
Local Met just said that it is now officially Tropical Storm Bonnie per the HH
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Quoting scott39:
Levi, What does Decoupling mean to Bonnie?


Most of the day the storm has not been vertically stacked. It looks as if shear has been preventing the storm from getting line up vertically in the atmosphere.
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Quoting zoomiami:
Not that many people will care, but for those of you who think that this is an opportunity for the smart alec comments, you are doing a disservice for the others who are coming here to get real information.

I think its a shame that a blog that has been known for being on top of the game has degenerated to the stupidity of those who don't have anything better to do.

And no, they are not all teenagers.


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1153. 900MB
Quoting TampaSpin:
If everyone would hit the minus sign for a bad post it would eliminate of a lot of posting at this time...i have been doing it and it works really well...


Funny, yours was hidden for no reason. I haven't been hitting the + and -, but I'll start now with a + for you. I like your posts.
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http://weather.cod.edu/analysis/loops/satmaster.pl?Carribbean

Center between Long island and Exuma.

Perfectly clear it is still under the south side of the convection.

Follow all the low level bands and triangulate your center.

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1151. Patrap
One can see the Ridge building in from the East in the Upper Right.

TS Bonnie Floater - Rainbow Color Infrared Loop
Member Since: July 3, 2005 Posts: 421 Comments: 127559
1150. KEEPEROFTHEGATE (Mod)
Quoting vortextrance:


Unfortunately true. Bonnie is pathetic looking compared to Katrina at this point. Katrina was much larger with a lot more organized convection at this point. She also wasn't fighting shear and dry air. If Bonnie were anywhere but on Florida's front yard you wouldn't be hearing RI talk.


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Quoting CaneWarning:
RIP Bonnie.



RIP Caster
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Quoting CaneWarning:
RIP Bonnie.
you people have nothing better to do ?????
Member Since: July 14, 2009 Posts: 0 Comments: 2990
1147. raggpr
They have tropical storm Bonnie on the nhc floater and on the wunderground page.
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RIP Bonnie.
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1145. Levi32
Quoting scott39:
Levi, What does Decoupling mean to Bonnie?


It means that south Florida still doesn't need to be concerned for anything more than weak tropical storm conditions, which is still a big deal but not a highly dangerous situation. Bonnie will probably weaken in the gulf and never become more than what she is now, a solid TS but on the low side.
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1144. Patrap
TS Bonnie Morphing into a newer version tonight.
Member Since: July 3, 2005 Posts: 421 Comments: 127559
Quoting hydrus:
The further north it goes, the more strength it can gain....Better outflow...jmo

Right, but according to StormW earlier the steering layers to the north will prevent much more of a northwest track and should begin to see the west north west track
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Quoting Hurricanes101:
yup sure looks like Bonnie is decoupling


If that's the case, and it's truly decoupled, then the only shot is has is quickly regenerating a new low under the convection or it's done.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting Patrap:
Hunker down dem Curtains..



Thanks Pat for the graphics postings, keeeps me from flipping back and forth. I am looking at some serios rain in the next couple of days.
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1140. Patrap
Dont yell at me. I just post um..
Note the Gusts

NEXRAD Radar
Miami, Velocity Azimuth Display Wind Profile Range 124 NMI


Member Since: July 3, 2005 Posts: 421 Comments: 127559
1139. Levi32
Quoting HurricaneSwirl:


Thanks for the analysis, Levi. Is it possible that the MLC will take over though?


Doubtful because in this kind of a situation the best environmental conditions and lowest surface pressures are to the south, not to the north. The NW path is the most favorable for intensification because of the upper low backing away, but the low-level steering flow will be trying to tug the low-level center westward. The mid-level center will eventually follow but for now the two are parting ways.
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i think the center is broad, and not decoupled, just my opinion, and it looks to be reforming, well see
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looks like its moveing W now
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1136. Patrap
Quoting sarahjola:
bob brecks viper says its coming up the mouth of the river:)his hair piece says its going more west:)


I did NOT Like the Viper run.

Bobs Such a Jar-head I tell Him.
Member Since: July 3, 2005 Posts: 421 Comments: 127559
Overreation to a state of emergency for Bonnie.........Hail no!! We have a ton of oil off our coast and no one knows what the final result will be*** This is just a trial run for the big boomers that may form later in the GOM. There are 650 miles of boom from the gusher. The spill is about the size of the state of Utah.
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1133. scott39
Levi, What does Decoupling mean to Bonnie?
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1132. Patrap
Hunker down dem Curtains..

Member Since: July 3, 2005 Posts: 421 Comments: 127559
Quoting unf97:


Yes, that is correct in what Dr. Masters pointed out.

I think Andros Island is the point where I think it will go farthest north. If for some reason Bonnie moves north of Andros Island, then watches will have to be posted a little farther up the coast, but this scenario I think is unlikely.

I am expecting the turn to W-W/NW to happen in the next few hours. Heights are rising just north and northwest of the cyclone, indicating that ridge is building in.


Thanks!
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convective burst look great right now
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1129. redUK
Quoting Hurricanes12:
Is it possible that this system is capable of growing stronger, possibly into a minimal hurricane before reaching S.FL? Or even a Strong TS?


Could be the odd hurricane strength gust but these will be few and far between. [just IMHO]
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1128. Patrap
Rum and Raisinets ?
Member Since: July 3, 2005 Posts: 421 Comments: 127559
Quoting Hurricanes12:
Is it possible that this system is capable of growing stronger, possibly into a minimal hurricane before reaching S.FL? Or even a Strong TS?


Anything is possible....but not probable.

I guess 50-60 mph as it crosses mid to upper keys.

In Naples now. we need the rain.
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Quoting Hurricanes12:
Is it possible that this system is capable of growing stronger, possibly into a minimal hurricane before reaching S.FL? Or even a Strong TS?


Their are no absolutes but it would seem very unlikely to make hurricane status.
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Quoting hurricaneben:


Well I recall The Weather Channel said 20-30 MPH winds and some heavy rainfall of over 2 inches???


Isn't that what I just posted?
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1124. Levi32
Quoting mcluvincane:


Um that's what the nhc said at the 5 and it strengthened.. lol


No, it got better organized. The winds have been TS-strength since this was near the Dominican Republic.
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Quoting Hurricanes12:
Is it possible that this system is capable of growing stronger, possibly into a minimal hurricane before reaching S.FL? Or even a Strong TS?


It could, but not so likely. Of course I'd rather believe that than a cat.4 or cat.5 from this thing devastating the area.
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bob brecks viper says its coming up the mouth of the river:)his hair piece says its going more west:)
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yup sure looks like Bonnie is decoupling
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Quoting Kristina40:


I don't think it is. Have they fixed the levies? Even if it comes in as a weak Hurricane it could cause major problems, especially carrying oil inland with it.


What a joke he is
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Quoting Levi32:
New recon pass shows the low-level center moving west of the previous vortex message and weaker....mid-level center decoupling northeast of it with the convective burst. NW motion cannot be sustained in this situation which is why the models taking this into central Florida were ridiculous. This may still clip through very southern Florida but it may have a shot still at the straights as well. Bonnie is not strengthening right now.



Thanks for the analysis, Levi. Is it possible that the MLC will take over though?
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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.

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