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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In performing my analysis this morning based on satellite imagery, computer model data, and steering pattern, I'm quite confident in a forecast that would see a moderate tropical storm making landfall tomorrow afternoon in Southern Miami Dade county.
Member Since: Posts: Comments:
Quoting FLdewey:
Looks like a hard rain in Ohio.


i've seen that before, it's old.
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Quoting DestinJeff:
Cuba has a Thought Bubble:


LMAO
Member Since: March 10, 2010 Posts: 1 Comments: 7816
The Miss. AL. gulf Coast is so small, that if TD3 Strengthens more than expected and goes on the E side of LA., it will be a 3 state event!
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TD 3 Floater - Rainbow Color Infrared Loop
Member Since: July 3, 2005 Posts: 426 Comments: 128636
Quoting MiamiHurricanes09:
Same here.

so what you saying is that broward county w ill be tropical storm warning????
Member Since: August 18, 2009 Posts: 0 Comments: 192
Quoting IKE:


LOL...but it cuts out half of the storm.


Best Loop Out There.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
210. JRRP
TD 3 and possible TD 4 ?
This season doesn´t look as bad
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Quoting IKE:


Yeah...I know...just funny for now to view 1/2 of a system. I guess they expect it to move fast!


Itsa Lot bigger than that Envelope shows as the overall circu is big Like..

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

Member Since: July 3, 2005 Posts: 426 Comments: 128636
Quoting btwntx08:
wow!!!! impressive

Makes you wonder why isn't it a TD yet.
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Blog Update!

July 22, 2010 - 11:55 AM EDT - Tropical Depression #3 Is Classified - 98L Organizing
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting ecflweatherfan:
If Central Florida was expected to get 35 to 45 mph winds, we would be under a Tropical Storm Warning as well, but we are not... So Matt Makens is wrong... NWS Melbourne not calling for more than 20 mph winds even at the coast... so 15 mph in Orlando.


Well he is a Met I am not, Matt could be right, he could be wrong, I have watched him for a few years and I respect his views we shall see how it pans out.
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guys GO TO the NHC SITE they hVE THIS awsome new track still trying to learn how to link
Member Since: July 21, 2010 Posts: 0 Comments: 1177
203. xcool
We Can See strong TS 65K.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
storm,what do you think the chances for a TS watch or warning for SRQ area???
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Quoting StormW:


Little further east in LA.
Thanks
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Patrap, I think you have to work for BP to get that.
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Quoting StormW:


Little further east in LA.


Well, That just made my day! Lol...
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Quoting MississippiWx:
Not trying to start any # of named storms debate, but TD2 and 98L could have easily been named storms if they had not developed so late. Seems that storms are trying to develop close to land this year and it's too late. We could easily have 3 named storms by now, with TD3 becoming the 4th named storm (not to mention the system that moved into SE Louisiana, 95L). Oh well, though.

By the way, the ULL is racing away from TD3.


98L still has a day to a day and a half over water.
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Someone got Knighted ?
Member Since: July 3, 2005 Posts: 426 Comments: 128636
193. IKE
Quoting Patrap:


That cuz there iz nothing behind it and the Threat is ahead..as it is moving west.



Yeah...I know...just funny for now to view 1/2 of a system. I guess they expect it to move fast!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
NEXRAD Radar
Miami, Storm Relative Mean Radial Velocity 0.50 Degree Elevation Range 124 NMI


Member Since: July 3, 2005 Posts: 426 Comments: 128636
Good afternoon everyone! Especially you Sir Storm.. What would I do without you?
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Quoting IKE:


LOL...but it cuts out half of the storm.


That cuz there iz nothing behind it and the Threat is ahead..as it is moving west.

Member Since: July 3, 2005 Posts: 426 Comments: 128636
189. xcool
keep up good job .StormW
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting StormW:


Little further east in LA.


not funny StormW!!
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Quoting StonedCrab:


Thanks Storm!
You're OK, I don't care what JFV says about you.

ROFLMAO, ouch..I think I hurt myself
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting StormW:


Little further east in LA.


SW LA?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
btwn, this is the other MX radar on the W coast of the GOM, at Tampico.



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184. IKE
Quoting Patrap:
NOAA Has Slewed TD 3 Floater to The Keys View


Floater - RGB Color Infrared Loop


LOL...but it cuts out half of the storm.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting BahaHurican:
Wow. That was ... unexpected... LOL

Thanks Doc. Very comforting to those of us "under the wx", so to speak.

From previous blog...

Why have a feeling?

AN AIR FORCE PLANE WILL BE IN THE AREA THIS AFTERNOON AND WILL HELP
TO DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL STORM.

LOL... I doubt the strengthening to cat 1 unless the storm slows down. I can see a movement slightly more north, like S tip of FL as opposed to Srn keys at most.

After that, don't know what to expect. However, I'm not seeing the ULL back far enough away from TD3 to allow for massive strengthening....

Warnings are for the rain, likely. For us, a TS can represent SIGNIFICANT flooding. When Noel went through here, someone drowned in the RAIN flooding (not storm surge).

thanks baha!
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Houstongal - what part of MS did you live during K?
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181. xcool
btwntx08 yeah.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
There is a small mid-level moisture channel entering the TD3 envrionment from the south as it wraps around the ULL, but otherwise the environment doesn't look very good for strengthening at all. I'd guess it may barely make TS and I suspect a sig chance of weakening during the next 24-48 h.
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Wonder if the Marlins game is gonna be Canceled lol.
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151. btwntx08 12:18 PM EDT on July 22, 2010
Quoting BahaHurican:
1) it's the best we've got for now, as the closer site at Holguin is offline [has been for a while, dunno why].

2) TD3/Possible Bonnie is supposed to track this way as the day progresses, so eventually Camaguey is likely to give some good views, esp. if the centre stays as far south as implied by early tracks.

look at the brownsville radar then it shows lots feeder bands

You're getting feeder bands... for TD3??? on the BROWNSVILLE radar...???

Maybe u meant the Veracruz one, eh? But u should have specified. I just assumed that u were talking about TD3 because already knew that wasn't well placed...
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TD-3 Floater - Rainbow Color Infrared Loop
Member Since: July 3, 2005 Posts: 426 Comments: 128636
Quoting StormW:
TROPICAL DEPRESSION THREE SYNOPSIS ISSUED 12:10 P.M. JULY 22, 2010
Again, Thank you Storm
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Not trying to start any # of named storms debate, but TD2 and 98L could have easily been named storms if they had not developed so late. Seems that storms are trying to develop close to land this year and it's too late. We could easily have 3 named storms by now, with TD3 becoming the 4th named storm (not to mention the system that moved into SE Louisiana, 95L). Oh well, though.

By the way, the ULL is racing away from TD3.
Member Since: Posts: Comments:

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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.