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 Hurricanes101:


you dont always get the strongest winds in the vortex message I have noticed

I have seen with most systems the actual winds reported by the NHC in advisories is higher than the highest surface wind reported in the vortex messages


Well because they round. The previous Vort fix has winds around 33-34mph.
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Quoting MiamiHurricanes09:
I understand that, I'm just showing the difference between the 5PM advisory and where the 1005.6mb reading was located.


Time: 21:18:00Z
Coordinates: 22.7833N 75.3333W
Acft. Static Air Press: 987.5 mb (~ 29.16 inHg)
Acft. Geopotential Hgt: 159 meters (~ 522 feet)
Extrap. Sfc. Press: 1005.6 mb (~ 29.70 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 356° at 4 knots (From the N at ~ 4.6 mph)
Air Temp: 25.1°C (~ 77.2°F)
Dew Pt: 21.6°C (~ 70.9°F)
Peak (10s) Flt. Lvl. Wind: 7 knots (~ 8.0 mph)
SFMR Peak (10s) Sfc. Wind: 20 knots (~ 23.0 mph)
SFMR Rain Rate: 3 mm/hr (~ 0.12 in/hr)
(*) Denotes suspect data
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Member Since: July 3, 2005 Posts: 428 Comments: 129902
Quoting Patrap:
Floater - Rainbow Color Infrared Loop

Looking quite ragged at the moment.
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Looking at the satelite presentations it appears that TD3 made a more northerly shift.
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Quoting Hurricanes101:


21:18:00Z 22.783N 75.333W 987.5 mb
(~ 29.16 inHg) 159 meters
(~ 522 feet) 1005.6 mb
(~ 29.70 inHg)


I see it right about where the 5pm was
Weird. I Wonder where I got that location from.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Floodman:


Hot towers are pretty exclusively eyewall features...no eye, no eyewall, no eyewall, no hot towers (at least in this context)


He wast talking about the tower of mash potatoes he left out side. It became hot, so it went boom, to the floor.
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Quoting tropicfreak:
Storm, hurrkat(or stormkat) has a question for you about the ULL.


Hahahahaha.
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Quoting ElConando:


That ain't a vort fix so not convinced yet.


you dont always get the strongest winds in the vortex message I have noticed

I have seen with most systems the actual winds reported by the NHC in advisories is higher than the highest surface wind reported in the vortex messages
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Quoting Floodman:


Hot towers are pretty exclusively eyewall features...no eye, no eyewall, no eyewall, no hot towers (at least in this context)


then a huge area of intense convection is beginning to erupt near the center.
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Quoting FLdewey:
This blog is like teen night at the local skating rink.


YEAH!!
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Just my many, many, many years of watching these tropical storms, when they pass to the South, the majority of the rain is to the North. Depending on how strong the system is as it approaches the Keys, it should still be a large rain event perhaps as far North as Palm Beach County.
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Time: 21:05:00Z
Coordinates: 22.9833N 74.7667W
Acft. Static Air Press: 988.0 mb (~ 29.18 inHg)
Acft. Geopotential Hgt: 174 meters (~ 571 feet)
Extrap. Sfc. Press: 1008.0 mb (~ 29.77 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 111° at 36 knots (From the ESE at ~ 41.4 mph)
Air Temp: 23.1°C (~ 73.6°F)
Dew Pt: 21.0°C (~ 69.8°F)
Peak (10s) Flt. Lvl. Wind: 38 knots (~ 43.7 mph)
SFMR Peak (10s) Sfc. Wind: 43 knots (~ 49.4 mph)

SFMR Rain Rate: 23 mm/hr (~ 0.91 in/hr)
(*) Denotes suspect data

Here is another one looking real good
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i like too see a few more pass this too make sure
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Quoting Drakoen:
It looks like TD3 is on track for a south Florida Landfall. System is east of the forecast points. On another note, TD3 is getting better organized, you can see how the system has managed to wrap around convection on the western side on satellite imagery.


Thats what I was saying. You stole mine. LOL!!
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Quoting MiamiHurricanes09:
I understand that, I'm just showing the difference between the 5PM advisory and where the 1005.6mb reading was located.


21:18:00Z 22.783N 75.333W 987.5 mb
(~ 29.16 inHg) 159 meters
(~ 522 feet) 1005.6 mb
(~ 29.70 inHg)


I see it right about where the 5pm was
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Quoting Seflhurricane:
Time: 21:04:00Z
Coordinates: 23.0167N 74.7333W
Acft. Static Air Press: 987.5 mb (~ 29.16 inHg)
Acft. Geopotential Hgt: 183 meters (~ 600 feet)
Extrap. Sfc. Press: 1008.2 mb (~ 29.77 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 110° at 40 knots (From the ESE at ~ 46.0 mph)
Air Temp: 25.0°C (~ 77.0°F)
Dew Pt: 21.4°C (~ 70.5°F)
Peak (10s) Flt. Lvl. Wind: 42 knots (~ 48.3 mph)
SFMR Peak (10s) Sfc. Wind: 38 knots (~ 43.7 mph)
SFMR Rain Rate: 7 mm/hr (~ 0.28 in/hr)
(*) Denotes suspect data

recent pass we are at TS status


That ain't a vort fix so not convinced yet.
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Quoting StormW:
Good evening!

Good evening Storm!
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Quoting Twinkster:


I'm no expert but i think it is the opposite. Stronger systems tend to go more north whereas a weaker storm would go more south. The reason the model guidance is sold on a keys landfall is that steering layers are fairly straightforward in indicating that a weak system would head wnw and the models don't see much strengthening. If the system becomes a strong TS then we could be talking a shift right in models and more of a chance of landfall in miami-dade county with most of rain affecting broward and palm beach county


It does not always work that way. The steering currents change depending upon how "Deep"
the system is and the upper level steering current synoptic setup.

A stronger storm reaches deeper into the atmosphere and is steered by upper level winds differently.
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Quoting Hardcoreweather2010:
Not happy with the shift to the east




at lest FL is out of the woods un lees you live int he FL keys that is
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Best Batten down the curtains,..

er...I mean Hatches,,hatches
Member Since: July 3, 2005 Posts: 428 Comments: 129902
Quoting tropicfreak:


Well your forecasting is great.


Haha, you wouldn't be saying that if it was year ago, was a bad year in forecasting for me, the only one I pinned was Bill. After studying more on the patterns and stuff, being that I had time to, I'm trying to be as accurate as I can this year.
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Quoting Drakoen:


No. The center is located up near 22.7N 75.3W. System continues to move to the NW.
I understand that, I'm just showing the difference between the 5PM advisory and where the 1005.6mb reading was located.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
What level of winds determine a TS.. 45mph?
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Quoting leo305:
hot tower going boom


Hot towers are pretty exclusively eyewall features...no eye, no eyewall, no eyewall, no hot towers (at least in this context)...
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Quoting omgonozohshite:
\

stormdog! Whats crappenin my man?

How soon till that biotch bonnie rears her breakfast?


Please be considerate of the youngins on the blog. Thanks!
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Time: 21:04:00Z
Coordinates: 23.0167N 74.7333W
Acft. Static Air Press: 987.5 mb (~ 29.16 inHg)
Acft. Geopotential Hgt: 183 meters (~ 600 feet)
Extrap. Sfc. Press: 1008.2 mb (~ 29.77 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 110° at 40 knots (From the ESE at ~ 46.0 mph)
Air Temp: 25.0°C (~ 77.0°F)
Dew Pt: 21.4°C (~ 70.5°F)
Peak (10s) Flt. Lvl. Wind: 42 knots (~ 48.3 mph)
SFMR Peak (10s) Sfc. Wind: 38 knots (~ 43.7 mph)
SFMR Rain Rate: 7 mm/hr (~ 0.28 in/hr)
(*) Denotes suspect data

recent pass we are at TS status
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Quoting hydrus:
Take a look at this loop. You can see the ULL moving rapidly west and trying(and shearing) 97L in a N.W. direction.Link


Ummmm.. you mean TD 3
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Quoting catastropheadjuster:

Just thought I would throw this in. My son just called he in Grand Isle,LA working and he just told me that tommorrow morning there suppose to start evacuating grand isle, he want be leaving until 20 hours before it comes in, there take the cranes apart and everything. He called me to let me know, I told him I didn't think it was gonna get bad. Heck I just don't know what to think.
Sheri
oops put years instead of hours. thank Angie

``````
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One can see the ridge building in on the Upper Right

Check the MSLP box as well

Floater - Rainbow Color Infrared Loop
Member Since: July 3, 2005 Posts: 428 Comments: 129902
3 is still going more to the north of forecast points
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Not happy with the shift to the east

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Quoting MiamiHurricanes09:
5PM EDT advisory coordinates: 22.7N 75.4W
Latest lowest pressure reading location: 22.4N 75.2W. Apparently 03L moved to the SE.


No. The center is located up near 22.8N 75.3W. System continues to move to the NW.
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Quoting caneswatch:


No sir I din't. What did it say?


I don't remember. I think I said something.
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Quoting Tazmanian:
at the rate of falling mb we could see a hurricane in the gulf may be even a strong hurricane if the wind shear is low


Then that will scare the crap out of the gulf coast.
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Quoting Grecojdw:



But I was under the impression from all that I have learned here on this blog that as a storm gets stronger, it tends to have a northernly component since it tends to have more of a poleward movement??? Some of the more knowledgeable could clarify this for me.


that depends if there is something to the N to block poleward movement
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Tropical Update with all MOdels and Graphics
Member Since: September 2, 2007 Posts: 179 Comments: 20448
am vary sure about %80 ch we have a TS now
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Quoting Drakoen:
It looks like TD3 is on track for a south Florida Landfall. System is east of the forecast points. On another note, TD3 is getting better organized, you can see how the system has managed to wrap around convection on the western side on satellite imagery.
Agreed. Satellite presentation is improving despite the recent minor wane of convection.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting scottsvb:
Even I'm alittle surprised this isnt Bonnie.. pressure around 1006mb surface winds near 40mph.. (you have to assume there might be a 2-5mph stronger wind somewhere) this should be a 40mph system...but doesnt matter..its not yet. Also seems to of drifted NNW over the past 1-2hours...but probably a wobble as expected.


Hey Scott,

I have to agree with you. especially with the current pressure drops occurring with TD3.
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Storm, hurrkat(or stormkat) has a question for you about the ULL.
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Quoting smmcdavid:


21 and a half? I thought halves ended after about 10?! ;-)


well technically, since my birthday is on November 27th, I am 21 (and a half) :P
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Quoting Drakoen:
It looks like TD3 is on track for a south Florida Landfall. System is east of the forecast points. On another note, TD3 is getting better organized, you can see how the system has managed to wrap around convection on the western side on satellite imagery.


huge hot tower erupting over the system
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Getting the first feeder bans from TD3. First time in S Fla since Fay.
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at the rate of falling mb we could see a hurricane in the gulf may be even a strong hurricane if the wind shear is low
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Member Since: July 3, 2005 Posts: 428 Comments: 129902

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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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