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 Patrap:
18z Early Cycle NHC model tracks
Invest97
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)



Ya know Pat, not sure if I'm willing to "Take one for the team" so to speak, but these plots don't bode well for the well.
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Quoting tropicfreak:
Its starting to wrap around, meaning strengthening, however t'storm activity has decreased for the time being.


it's breathing.. the outflow is developing, its about to go boom
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THE NHC says:

THE DEPRESSION WILL BECOME EMBEDDED WITHIN A
DEEP EASTERLY FLOW AND SHOULD BEGIN TO MOVE MORE TO THE
WEST-NORTHWEST WITH AN INCREASE IN FORWARD SPEED.


So yes, it is moving to the NW now. That is expected hence anything you see here: http://www.nhc.noaa.gov/

But if it CONTINUES this track, that's when the track will (if) changes.

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Quoting TropicalNonsense:
if TD3/Bonnie strengthens she will move in a more W/WNW as she
approaches the coast and the center should stay off the coast.

If she continues to remain weak the steering pattern may
tend further NORTHWEST which may increase the chances for
more of a Florida impact.

I am pretty sure this is the NHC's forecast thinking.

watch for a more W-WNW movement in the next 8
hours or so.


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
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463. xcool
LMAO
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Quoting hurrkat05:
HYDRUS IM PROUD OF YOU YOU FINALLY GET WHY THE TROPICAL DEPRESSION IS BEING SHEARED...GOOD JOB


Ma'am I am asking you to look at the facts.
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1005.6mb pressure reading, note the coordinates.

000
URNT15 KNHC 222121
AF306 02BBA INVEST HDOB 43 20100722
211230 2246N 07503W 9877 00173 0074 +246 +205 157032 033 034 003 00
211300 2246N 07503W 9877 00173 0072 +250 +204 160031 032 033 002 00
211330 2244N 07506W 9872 00176 0071 +250 +205 166029 031 032 002 03
211400 2244N 07508W 9879 00168 0069 +250 +206 176028 029 030 005 03
211430 2244N 07509W 9873 00172 0068 +248 +208 177026 027 029 002 00
211500 2244N 07511W 9875 00170 0068 +247 +210 181024 024 029 004 00
211530 2244N 07512W 9882 00162 0066 +248 +211 190021 023 029 001 03
211600 2244N 07514W 9877 00165 0066 +245 +212 197015 017 025 001 00
211630 2244N 07516W 9882 00158 0062 +250 +213 224014 014 022 004 03
211700 2245N 07517W 9872 00164 0059 +250 +214 210015 016 024 002 03
211730 2246N 07518W 9879 00156 0057 +253 +215 247005 006 023 001 03
211800 2247N 07520W 9875 00159 0056 +251 +216 356004 007 020 003 00
211830 2248N 07521W 9880 00155 0057 +250 +217 041013 014 013 006 03
211900 2248N 07522W 9870 00167 0060 +249 +218 036012 013 018 004 03
211930 2247N 07523W 9877 00164 0063 +250 +219 023010 010 021 002 00
212000 2245N 07525W 9875 00168 0065 +248 +219 009010 011 017 004 00
212030 2244N 07526W 9879 00165 0067 +245 +219 348011 012 021 003 00
212100 2243N 07527W 9877 00169 0069 +245 +218 343009 010 022 000 00
212130 2242N 07528W 9879 00168 0070 +245 +217 342007 008 019 002 00
212200 2241N 07530W 9876 00172 0071 +247 +217 348007 007 020 002 00
$$
;
Member Since: September 2, 2009 Posts: 130 Comments: 21194
To note, unlike the last readings of TS all these readings the aircraft was at a steady 580-600 altitude and flight level winds are in support of a TS.
Member Since: July 8, 2005 Posts: 259 Comments: 24186
I'll make my first run on TD3 later, or maybe it will be Bonnie.
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oh no us who thought we saw TS force winds earlier may have either been right or off by 1 hour

may us be prosecuted by the law to the fullest extent lol
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Quoting CybrTeddy:
Flight level winds do support TS status..


Lets just see what they put as the vortex message.
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Its starting to wrap around, meaning strengthening, however t'storm activity has decreased for the time being.
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18z Early Cycle NHC model tracks
Invest97
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)



Member Since: July 3, 2005 Posts: 426 Comments: 128668
Quoting CybrTeddy:
Flight level winds do support TS status..
So do SFMR winds.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
TD03/Bonnie is about to enter warmer and deeper waters shortly. This coupled with the ULL's rather quick exit stage left may give the system its best chance at organization. Wouldn't be surprised to see at 50 MPH storm at 11 tonight.

Also, an important thing to note is the angle at which the storm is approaching the southernmost tip of Florida. Any deviation from forecast track, even a few miles, may be the difference between a landfall on the mainland and in the keys.
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Flight level winds do support TS status..
Member Since: July 8, 2005 Posts: 259 Comments: 24186
Quoting Grothar:
DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM EDT...2100 UTC...THE CENTER OF TROPICAL DEPRESSION THREE
WAS LOCATED NEAR LATITUDE 22.7 NORTH...LONGITUDE 75.4 WEST. THE
DEPRESSION HAS BEEN MOVING TOWARD THE NORTHWEST NEAR 14 MPH...22
KM/HR. A TURN TO THE WEST-NORTHWEST WITH AN INCREASE IN FORWARD
SPEED IS EXPECTED TONIGHT AND FRIDAY.

DATA FROM A RECONNAISSANCE PLANE INDICATE THAT THE DEPRESSION HAS
NOT STRENGTHENED. MAXIMUM SUSTAINED WINDS REMAIN NEAR 35 MPH...55
KM/HR...WITH HIGHER GUSTS. SOME STRENGTHENING IS POSSIBLE AND THE
DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT OR FRIDAY.

THE MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE RECONNAISSANCE
PLANE WAS 1006 MB...29.71 INCHES.



Forward speed may be slowing. The HH found the center of TD3 25 miles SE of the position stated in this 5 pm, 20 minutes later at 5:20 pm Eastern.
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Quoting BenBIogger:


Some dry air at the mid-levels. but I expect a Good D-max for TD3 tonight or early morning.


Hurrikat meant like chocking dry air.. there is some very light dry air in the mid levels. I agree, a good DMAX can get this going.
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Quoting CJ5:
Heck, had I picked up that this was StormTop, eh, STORMKAT, whatever, I would not have wasted time on him earlier today.

I can now just laugh and look forward to the forecasts from his office as this system progresses..LOL



Thats what I was trying to say.
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Quoting hurrkat05:
lol tx yougoing to eat a lot of crow and better yet when STORM W mentions this ull over sw fla you maty believe him...i can see you dont know how to read weather charts..


That goes along with typing in English huh??? oooops
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Uncontaminated SFMR reading of 52mph (45 knots).

210430 2300N 07445W 9875 00181 0080 238 214 110041 043 045 017 00
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting hurrkat05:
well cast it aside i said and ill say it again the dry air is pouring in to the sw side of the tropical depression and if it's not named bonnie at 11pm it won't be...also the ull off the coast of sw fla will keep bonnie if she is named from becoming a hurricane as it approaches the la coast on sunday night...


ma'am please listen to the experts, the ULL is pulling away therefore meaning, low shear, less dry air, and gradual strengthening.
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Quoting atmoaggie:

Shame that HyCOM doesn't fully include the Lake. With a stout east wind, the Lake water surface tilts and draws in a bunch of the MS sound. But HyCOM, at least in this graphic, isn't capable of modeling that.





When and if the oil hits brackish water does it act differently?
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Quoting CybrTeddy:
Flight level winds..
43 knots
(~ 49.4 mph)

SFMR
45 knots
(~ 51.7 mph)

Flight level winds reduced..
42.9 knots (~ 49.3 mph)
Tropical Storm

Probably a 40 mph TS.


Agree.
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Quoting CybrTeddy:
Flight level winds..
43 knots
(~ 49.4 mph)

SFMR
45 knots
(~ 51.7 mph)

Flight level winds reduced..
42.9 knots (~ 49.3 mph)
Tropical Storm

Probably a 40 mph TS.
will get the lowest pressure in next recon report
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Quoting CosmicEvents:
Reed, do you ever recall a time when your forecast was LESS agggressive than the NHC forecast?


TD2 of this year.. heck what a joke that was, but it happened. I'm not saying it will in no doubt be a Hurricane, I can't because things can change. Conditions are favorable for a bit more intensification then what was previously thought.
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Quoting MiamiHurricanes09:
Recon finding TS winds...again. If we can get a vortex message indicating that winds are above 40mph a TS at 8PM EDT is likely.


Winds are a bit higher so it MAY get somewhere in the ballpark of 37-38 mph. If its higher than 37.5 they may upgrade.
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if TD3/Bonnie strengthens she will move in a more W/WNW as she
approaches the coast and the center should stay off the coast.

If she continues to remain weak the steering pattern may
tend further NORTHWEST which may increase the chances for
more of a Florida impact.

I am pretty sure this is the NHC's forecast thinking.

watch for a more W-WNW movement in the next 8
hours or so.
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting reedzone:


I see no "dry air".. everything's a go for gradual intensification ;)


Some dry air at the mid-levels. but I expect a Good D-max for TD3 tonight or early morning.
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Blog related question on ignoring individuals...

I have my filter set for show average on comments. Sometimes an individual who is below average, I want to hide them just because of never ending comments eating up huge amounts of screen.

When I expand the comment I do not see the quote or ignore user feature (but other times it is right their). Is anyone else seeing this issue?

Example post #354 (nothing) vs. 414 (ignore available)
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Flight level winds..
43 knots
(~ 49.4 mph)

SFMR
45 knots
(~ 51.7 mph)

Flight level winds reduced..
42.9 knots (~ 49.3 mph)
Tropical Storm

Probably a 40 mph TS.
Member Since: July 8, 2005 Posts: 259 Comments: 24186
432. xcool
TS


210430 2300N 07445W 9875 00181 0080 +238 +214 110041 043 045 017 00
210500 2259N 07446W 9880 00174 0080 +231 +210 111036 038 043 023 00
210530 2258N 07448W 9880 00178 0084 +226 +203 132032 035 046 019 03
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Quoting seflagamma:



You got that right Pat! And no one can "Mom" better than me! :o)

sometimes the foolishness is just too much...
and I love a good time and all but...


Mom-caster.

Itsa good thang Gamma.

Member Since: July 3, 2005 Posts: 426 Comments: 128668
Quoting angiest:


ECWMF is doing something similar now.


Also the last frame hr 126 of the HWRF close up of the td3 is also showing something.
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting stormhank:
Is the Florida Panhandle off the hook so to speak?? I noticed a slight right shift in the models since this morning?? any input appreciated...Thanks


No. Anywhere along the northern gulf coast is in play.
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Recon finding TS winds...again. If we can get a vortex message indicating that winds are above 40mph a TS at 8PM EDT is likely.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting P451:
Guessing a minimal TS at landfall at this rate of organization. 45mph?

Just doesn't seem to want to get going much - same problem every system has had this year so far.

I see what you mean. Now that the ULL is moving away faster, it looks like T.D.3 is getting dragged along with it and being sheared in that direction during the process.
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42.9 knots (~ 49.3 mph)
Tropical Storm
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42.9 knots (~ 49.3 mph)
Tropical Storm
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Quoting duprk452:
Pat, I know you like to keep us updated on the oil spill. My husband drives a tug out of Cocodrie, La which is working for BP right now. They just evacuated the area. All boats are being sent in and are on standby until further notice. The floating city and all of its crew are also doing the same. Looks like the clean up is at a standstill for the moment.


Yeah..the Marine Radio is all about Yakking on the Storm and Track
Member Since: July 3, 2005 Posts: 426 Comments: 128668
Quoting HurricaneGeek:
I see that its jogged to the N, but really what's impeding another jog to the S?
I just think a jog to the N is just that, a jog. I know a lot of jogs add up, but just like anything else, it's got to be consistent.
I'm not saying yes, it's going N o yes it's going S I'm just want to say, consistency is crucial.


true, I guess we will see what the next update brings us.
Member Since: July 2, 2009 Posts: 0 Comments: 2811
I'm not one to usually stare at satellite imagery however looking at visible imagery it is very interesting to see this system moving NW and being N of forecast points.

If this trend continues it is worrying, however, the NHC did say it will resume wnw later this evening. I will not think the track or cone will shift more north and east unless this continues past the 8 advisory
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420. xcool
210430 2300N 07445W 9875 00181 0080 +238 +214 110041 043 045 017 00
210500 2259N 07446W 9880 00174 0080 +231 +210 111036 038 043 023 00
210530 2258N 07448W 9880 00178 0084 +226 +203 132032 035 046 019 03
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Quoting reedzone:


I see no "dry air".. everything's a go for gradual intensification ;)


Reed.. don't quote him.
Member Since: July 8, 2005 Posts: 259 Comments: 24186

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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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