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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Quoting HurricaneFCast:

Actually it would be descent...


Yup, thanks
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Quoting MississippiWx:
98L still has way too broad of a circulation to become a tropical cyclone. If it had 2 more days over water, then sure. It just doesn't have time.


I disagree. I don't see why it would take 2 whole days for a circulation to tighten.
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Sorry to be a dense 33 year old here, but could we be possibly looking at some flooding if you live outside of the levee protection system in Plaquemines? (Have not had enough coffee yet, my mind is not working :( )
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Tropical Depression THREE Public Advisory
--------------------------------------------------------------------------------
Home Public Adv Fcst/Adv Discussion Wind Probs Maps/Charts Archive

US Watch/Warning
--------------------------------------------------------------------------------



000
WTNT33 KNHC 221737
TCPAT3
BULLETIN
TROPICAL DEPRESSION THREE INTERMEDIATE ADVISORY NUMBER 1A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032010
200 PM EDT THU JUL 22 2010

...AIR FORCE RECONNAISSANCE PLANE CURRENTLY APPROACHING THE
DEPRESSION...


SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...22.3N 74.9W
ABOUT 250 MI...400 KM SE OF NASSAU
ABOUT 400 MI...650 KM ESE OF KEY LARGO FLORIDA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/HR
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 15 MPH...24 KM/HR
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* CENTRAL AND NORTHWESTERN BAHAMAS
* FOR THE FLORIDA EAST COAST FROM GOLDEN BEACH SOUTHWARD INCLUDING
THE ENTIRE FLORIDA KEYS AND FLORIDA BAY...AND ALONG THE WEST COAST
OF FLORIDA NORTHWARD TO BONITA BEACH

A TROPICAL STORM WATCH IN IN EFFECT FOR...
* THE EAST COAST OF FLORIDA NORTH OF GOLDEN BEACH TO JUPITER INLET
INCLUDING LAKE OKEECHOBEE

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
RECENT VISIBLE SATELLITE IMAGES SHOW THAT THE CENTER IS A LITTLE TO
THE NORTHEAST OF THE LOCATION PREVIOUSLY INDICATED. AT 200 PM
EDT...1800 UTC...THE CENTER OF TROPICAL DEPRESSION THREE WAS
ESTIMATED NEAR LATITUDE 22.3 NORTH...LONGITUDE 74.9 WEST. THE
DEPRESSION HAS MOVED LITTLE DURING THE PAST FEW HOURS. HOWEVER...IT
SHOULD BEGIN TO MOVE TOWARD THE WEST-NORTHWEST NEAR 15 MPH...24
KM/HR SOON...WITH A GRADUAL INCREASE IN FORWARD SPEED.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. A RECONNAISSANCE PLANE IS CURRENTLY APPROACHING THE
DEPRESSION AND WILL DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL
STORM.

DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
RECENT VISIBLE SATELLITE IMAGES SHOW THAT THE CENTER IS A LITTLE TO
THE NORTHEAST OF THE LOCATION PREVIOUSLY INDICATED. AT 200 PM
EDT...1800 UTC...THE CENTER OF TROPICAL DEPRESSION THREE WAS
ESTIMATED NEAR LATITUDE 22.3 NORTH...LONGITUDE 74.9 WEST. THE
DEPRESSION HAS MOVED LITTLE DURING THE PAST FEW HOURS. HOWEVER...IT
SHOULD BEGIN TO MOVE TOWARD THE WEST-NORTHWEST NEAR 15 MPH...24
KM/HR SOON...WITH A GRADUAL INCREASE IN FORWARD SPEED.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. A RECONNAISSANCE PLANE IS CURRENTLY APPROACHING THE
DEPRESSION AND WILL DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL
STORM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.




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I'm not getting any dropsonde info since OB 12 west of Ft Myers...anyone else?
Member Since: October 30, 2007 Posts: 0 Comments: 270
extreme,that area of 20-25kt sheer needs to move a bit further south and let td3 breath and tonight thats what should happen,i wouldn't be suprised if we have a 60mph TS approaching the upper keys tomorrow...
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564. xcool
Getting Closer
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Not good for anyone, but Both of those tracked pretty much right over the Tampa Bay area. Going to see how well my chicken coop holds up.
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Quoting HoustonTxGal:
What would everyones educated guess be for where TD3 is going one she visits Florida?
I am guessing Lousiana coast, maybe New Orleans?
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The only thing i'm getting on google earth recon is misson 02 into second suspect area.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
With the new coordinates the cone should be shifted northward putting the northern keys in the "center line", however cones aren't released in intermediate advisories.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
98L still has way too broad of a circulation to become a tropical cyclone. If it had 2 more days over water, then sure. It just doesn't have time.
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RECENT VISIBLE SATELLITE IMAGES SHOW THAT THE CENTER IS A LITTLE TO
THE NORTHEAST OF THE LOCATION PREVIOUSLY INDICATED. AT 200 PM
EDT...1800 UTC...THE CENTER OF TROPICAL DEPRESSION THREE WAS
ESTIMATED NEAR LATITUDE 22.3 NORTH...LONGITUDE 74.9 WEST.
THE
DEPRESSION HAS MOVED LITTLE DURING THE PAST FEW HOURS. HOWEVER...IT
SHOULD BEGIN TO MOVE TOWARD THE WEST-NORTHWEST NEAR 15 MPH...24
KM/HR SOON...WITH A GRADUAL INCREASE IN FORWARD SPEED
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Quoting CaptDanny:

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


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What would everyones educated guess be for where TD3 is going once she visits Florida?
Member Since: September 18, 2007 Posts: 0 Comments: 1074
Quoting HurricaneFCast:


For those who are wondering: 4th column from the right are flight level peak winds (10 second average).. still north of TD3.. Near Nassau at the moment.Is that in knots or MPH
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Quoting ElConando:


Thats fairly North. What do you mean by region?


Since it's a bit hard for me at the moment to say exactly where... we can basically guess at this point that it should resume a more W to WNW patch as it approaches the Nassau area based on my current obs.
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Quoting Grothar:


Orca is not big enough!! LOL


Don't forget to hang the shower curtains!!!
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Quoting SQUAWK:


That would be "decent" to lower level.

Actually it would be descent...Lol..
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Quoting SQUAWK:


That would be "decent" to lower level.
LOL, I erased it because I was reading it incorrectly. Recon still at 377mb.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting nishinigami:
Hey Pat, from what I could tell from that link it showed a 9 ft wave forcast. What exactly would that mean? 9ft above normal? Sorry, I am easily confused by all of this


Wave forecast is 9 foot waves on the sea conditions.

Last Report I heard During K from Waveland 9am 29 2005..

Seas.."Phenomenal"..
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If the storm stays near the present NHC path I think for folks in SEFL and SWFL, the worst of the whatever weather is seen could be on Saturday and Sunday, as we get the butt-end of the cyclone when the center is NW of Key West.
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Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 22nd day of the month at 17:29Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Mission Purpose: Investigate second suspect area (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 07

Mandatory Data...

Observation Time: Thursday, 17:28Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 24.0N 76.4W
Location: 94 miles (152 km) to the SE (141°) from Nassau, Bahamas.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 7,580 meters
Flight Level Wind: From 130° at 21 knots (From the SE at ~ 24.1 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: -19°C
Flight Level Dew Point: -22°C
Weather (within 30 nautical miles): Overcast / Undercast
400 mb Surface Altitude: 7,590 geopotential meters
Member Since: October 30, 2007 Posts: 0 Comments: 270
Issued at: 1:37 PM EDT 7/22/10 (gateway).


Air force reconnaissance plane currently approaching the depression,

Summary of 200 pm edt, 1800 utc, information ---------------------------------------------- location, 22.3n 74.9w about 250 mi, 400 km se of nassau about 400 mi, 650 km ese of key largo Florida maximum sustained winds, 35 mph, 55 km/hr present movement, wnw or 295 degrees at 15 mph, 24 km/hr minimum central pressure, 1008 mb, 29.77 inches

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540. xcool
Hurricanes101 /IMO
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Quoting MiamiHurricanes09:
Recon still not in there, so a TD at 2PM is likely. At 5PM however is when we'll likely see a TS.

By the way, Recon has begun their accent towards the lower levels.


That would be "decent" to lower level.
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Hope Recon just has the SFMR off and there is not an issue with the recent change in decoding HDOB.
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SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...22.3N 74.9W
ABOUT 250 MI...400 KM SE OF NASSAU
ABOUT 400 MI...650 KM ESE OF KEY LARGO FLORIDA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/HR
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 15 MPH...24 KM/HR
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES
Member Since: September 2, 2009 Posts: 130 Comments: 21194
DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
RECENT VISIBLE SATELLITE IMAGES SHOW THAT THE CENTER IS A LITTLE TO
THE NORTHEAST OF THE LOCATION PREVIOUSLY INDICATED. AT 200 PM
EDT...1800 UTC...THE CENTER OF TROPICAL DEPRESSION THREE WAS
ESTIMATED NEAR LATITUDE 22.3 NORTH...LONGITUDE 74.9 WEST. THE
DEPRESSION HAS MOVED LITTLE DURING THE PAST FEW HOURS. HOWEVER...IT
SHOULD BEGIN TO MOVE TOWARD THE WEST-NORTHWEST NEAR 15 MPH...24
KM/HR SOON...WITH A GRADUAL INCREASE IN FORWARD SPEED.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. A RECONNAISSANCE PLANE IS CURRENTLY APPROACHING THE
DEPRESSION AND WILL DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL
STORM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.
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Quoting neonlazer:
Access forbidden..lol


Here Lazer DJ.



Have a Key,but yer on yer own.

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I see the Center Near 23.1N 75.2W heading West-Northwestward about 290 degrees
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting MississippiWx:


Too little, too late.


98L still has around 24 hours over water.
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Quoting Patrap:
Were gonna need a Bigger Boat..,Quint


GOM 84 Hour Wave Forecast (using SWAN) Model
Hey Pat, from what I could tell from that link it showed a 9 ft wave forcast. What exactly would that mean? 9ft above normal? Sorry, I am easily confused by all of this
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Quoting whs2012:


Oh, ok....well, why was my local met so sure that it was going to take the westward course if it got stronger?

Thanks!


Live TV? Could easily have misspoke.
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Quoting StormW:


Depends...have to get recon to get back the data with a good position and motion. Just looKed at current satellite loop imagery, and the convection "jumped" to the NW. This was utilizing WeatherTap, which gives a good clear closeup.


Storm, I posted a question on your blog.
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Quoting MississippiWx:


Too little, too late.
No...the COC is still a good 100-150 miles off shore.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Jeff, I see what you are talking about, however I think the weakness is only a temp. issue and will pinch off. Still thinking South Florida and out. Just my lay opinion
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outflow boudries at the surfdace noted on vis sat to the wsw of the circ center,indicating td3's ingesting drier air aloft,still expect slow organization/stregthening today,tonight i'd expect act 1 to truely begin!!!
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Quoting xcool:
98L TD4


I am not seeing that anywhere
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Quoting HurricaneFCast:
171230 2459N 07723W 3775 08025 0434 -201 -255 130031 032 /// /// 03
171300 2458N 07721W 3779 08017 0433 -197 -254 132033 034 /// /// 03
171330 2456N 07719W 3775 08023 0434 -195 -255 134033 034 /// /// 03
171400 2455N 07716W 3776 08023 0435 -193 -256 133035 037 /// /// 03
171430 2453N 07714W 3778 08018 0435 -190 -255 131037 038 /// /// 03
171500 2452N 07712W 3778 08022 0436 -190 -253 133035 035 /// /// 03
171530 2451N 07710W 3775 08027 0437 -194 -250 134033 034 /// /// 03
171600 2449N 07708W 3779 08019 0436 -194 -248 134031 032 /// /// 03
171630 2448N 07706W 3773 08031 0437 -195 -246 135029 030 /// /// 03
171700 2446N 07703W 3779 08020 0437 -194 -244 127029 029 /// /// 03
171730 2445N 07701W 3775 08029 0437 -195 -243 127029 029 /// /// 03
171800 2443N 07659W 3778 08022 0436 -191 -242 128030 031 /// /// 03
171830 2442N 07657W 3775 08028 0437 -189 -241 130030 030 /// /// 03
171900 2441N 07655W 3778 08022 0437 -188 -241 134028 028 /// /// 03
171930 2439N 07652W 3778 08022 0437 -190 -242 137026 028 /// /// 03
172000 2437N 07651W 3775 08025 0436 -192 -241 126025 026 /// /// 03
172030 2435N 07649W 3779 08017 0435 -193 -239 131019 020 /// /// 03
172100 2433N 07648W 3777 08023 0435 -193 -238 132017 019 /// /// 03
172130 2431N 07646W 3778 08020 0435 -193 -238 131015 015 /// /// 03
172200 2429N 07644W 3777 08022 0435 -195 -239 127015 018 /// /// 03


For those who are wondering: 4th column from the right are flight level peak winds (10 second average).. still north of TD3.. Near Nassau at the moment.
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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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