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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Worth Repeating

Please be careful with the hyperbole and misstatements of information.

Member Since: July 3, 2005 Posts: 421 Comments: 127702
Quoting MiamiHurricanes09:
That cone is likely inaccurate as there are several factors that the NHC are not sure of.


Really? I don't see it
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Quoting nola70119:


With the position of the oil and possible track, this could bring more into the MS for certain.


exactly - and I don't think they've finished installing the booms along Bay St. Louis and Biloxi Bay! I live up in the Kiln, and storm surge could funnel the oil up into the Jourdan River in my neck of the woods - not good at all!
Member Since: Posts: Comments:
Quoting ElConando:
Speaking of HH where he at?
Latest:

163200 2609N 08036W 3777 07998 0411 -235 -266 098022 023 /// /// 03

Over Broward moving into the Atlantic if brain is right on the location of coordinates, lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Patrap:
Opinions are not a FORECAST.



But a forecast can be a forecaster's opinion of the weather data he has available or somethign like that LOL!

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morning Pat
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265. xcool


BAD NEWS
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting southfla:
Patrap, you have any links to look at the potential rain amounts in TD3 ? I am wondering if its visit to PR and VI wrung out enough moisture that flooding won't be a big problem.


PR Had 8Plus so the TD has a History as a Wet one already..

Were outta Long Range Radar for Now as the Miami Doppler is the one Ill use as the Storm comes over the Hill to the CONUS.
Member Since: July 3, 2005 Posts: 421 Comments: 127702
It's a real pity we don't have wx observations available from Ragged Island chain....

According to Wunderground, TD3 is 74 miles from Duncan Town, and is likely to pass right over it....

Pity....
Member Since: October 25, 2005 Posts: 19 Comments: 21668
262. 7544
winds gusting to 45mph

wnw
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StormW, Dont you add the speed of a TCs forward motion to the East side winds and subtract it from the West side winds?
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Good early afternoon!

Forecast from the NWS for Key West, FL.

Tonight: A chance of showers and thunderstorms, mainly after midnight. Mostly cloudy, with a low around 80. Breezy, with a east wind around 20 mph. Chance of precipitation is 50%.

Friday: Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 88. Strong and damaging winds, with a northeast wind 20 to 25 mph increasing to between 40 and 45 mph. Winds could gust as high as 55 mph. Chance of precipitation is 60%.

Friday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 80. Breezy, with a south wind around 20 mph. Chance of precipitation is 50%.
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Quoting louisianaboy444:
To hit Miami Directly it would have to take the Extreme Northern Edge of the cone i don't see how yall seeing this happening?
That cone is likely inaccurate as there are several factors that the NHC are not sure of.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Patrap:
Opinions are not a FORECAST.



Best post of the year...
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Speaking of HH where he at?
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256. xcool
MScasinojunkie .I STAY IN Slidell :((((
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting 47n91w:


A quick search produced only one hurricane to impact (but not make landfall) California, more searching would be needed to confirm this:

1858 San Diego Hurricane
1939 Tropical Storm
1972 TD
1978 TD


California's protected by the cold Alaska current. If you ever come to California, you'll be as startled by the water temperature (brrrr!) as I was when I went to Florida... (Where's the camera? This can't be real... The ocean is supposed to be cold!)

The only way we ever get hit by a tropical storm is if they happen to get real strong at just the rate place off of Baja and turn north right in time to get sucked in by a fast moving trough. The cold water weakens them, but if the trough moves fast enough, it can survive long enough to get us.

I remember that TD of 1978... I was 6 and I asked my dad who the rain was chasing down the street. It wasn't falling, it was going sideways, which of course I'd never seen before living here.

So basically, the weather here is boring, but I've got family East of Houston so I watch your weather. Let's hope the ULL keeps TD3 and/or TS Bonnie in check, because the track looks similar to Rita.
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Patrap, you have any links to look at the potential rain amounts in TD3 ? I am wondering if its visit to PR and VI wrung out enough moisture that flooding won't be a big problem.
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To hit Miami Directly it would have to take the Extreme Northern Edge of the cone i don't see how yall seeing this happening?
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Quoting MiamiHurricanes09:
I don't like it either, but everything I'm looking at would coincide with what he is saying.


I'm not so sure. I don't make tracks outside the NHC cone. HH will come in soon and shed more light on this system. I stick with the Fl Straights a lil north of the consensus NHC track. This can change but for now...
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I'm seeing some less than careful things again.

TWO that coffee crusader quoted as being "7 a.m." was posted at 2 a.m. NHC changed it because conditions had changed. Moreover, the TWO hasn't been @ 20% for this system since, IIRC Monday sometime. It was 40% on the 2 a.m. and that can be easily verified at the NHC website.

Please be careful with the hyperbole and misstatements of information.

Member Since: October 25, 2005 Posts: 19 Comments: 21668
Quoting xcool:
NWS Slidell



TROPICAL DEPRESSION THREE IS FORECAST TO BECOME TROPICAL STORM
BONNIE LATER TODAY AND WILL AFFECT SOUTHEAST LOUISIANA...COASTAL
MISSISSIPPI AND THE ASSOCIATED GULF WATERS SATURDAY AND SUNDAY.
THE MAIN IMPACTS WILL REMAIN OVER THE GULF WATERS...WHERE
SUSTAINED TROPICAL STORM FORCE WINDS AND SEAS OF UP TO 8 FEET ARE
FORECAST. NEAR SHORE...EXPECT TIDES TO INCREASE BY TWO TO THREE
FEET ABOVE THE PREDICTED LEVELS DUE TO THE STRONG EASTERLY AND
SOUTHEASTERLY WINDS. STORM TOTAL RAINFALL WILL GENERALLY BE IN THE
TWO TO FOUR INCH RANGE WITH ISOLATED HIGHER AMOUNTS POSSIBLE.


Link



dang - there will definitely be flooding, this region is already saturated with the amount of rain we've been getting the last few months!
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put the current storm over middle fl keys and sfl still get nasty weather
Member Since: July 21, 2010 Posts: 0 Comments: 1092
Quoting MScasinojunkie:


exactly what I am afraid of!!


With the position of the oil and possible track, this could bring more into the MS for certain.
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Quoting Patrap:
Opinions are not a FORECAST.

Yes they are. What do you think a forecast is if not opinion?
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Hurricane Preparation 2010
Member Since: July 3, 2005 Posts: 421 Comments: 127702
Quoting FLdewey:
Looks like a hard rain in Ohio.



hilarious
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Quoting cchsweatherman:
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.


What are your ants up to?
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Storm...any prediction on a timeline for landfall?? Have plans to go to Fl next week for vacation and was wondering if this thing is supposed to stall or slow down...
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East of a TC is the beast!
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Every local met in the Orlando area is saying something different... this is the official point forecast from NWS Melbourne for the Southern Brevard County (closer to the center of the storm)... Friday: Scattered showers and thunderstorms, then showers likely and possibly a thunderstorm after noon. Mostly cloudy, with a high near 88. Windy, with a east wind between 15 and 20 mph, with gusts as high as 30 mph. Chance of precipitation is 60%.
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Quoting clwstmchasr:


I have a hard time believing TS force winds when the storm is going to be 200 miles away.


I am sure he means in gusts not sustained, and he said SFL will get the worst of the weather. He is not forecasting a direct hit for Central Florida by any means just outer bands of it.
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I like Data. It is good to use too.
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Member Since: July 3, 2005 Posts: 421 Comments: 127702
233. xcool
NWS Slidell



TROPICAL DEPRESSION THREE IS FORECAST TO BECOME TROPICAL STORM
BONNIE LATER TODAY AND WILL AFFECT SOUTHEAST LOUISIANA...COASTAL
MISSISSIPPI AND THE ASSOCIATED GULF WATERS SATURDAY AND SUNDAY.
THE MAIN IMPACTS WILL REMAIN OVER THE GULF WATERS...WHERE
SUSTAINED TROPICAL STORM FORCE WINDS AND SEAS OF UP TO 8 FEET ARE
FORECAST. NEAR SHORE...EXPECT TIDES TO INCREASE BY TWO TO THREE
FEET ABOVE THE PREDICTED LEVELS DUE TO THE STRONG EASTERLY AND
SOUTHEASTERLY WINDS. STORM TOTAL RAINFALL WILL GENERALLY BE IN THE
TWO TO FOUR INCH RANGE WITH ISOLATED HIGHER AMOUNTS POSSIBLE.


Link

Member Since: September 26, 2009 Posts: 2 Comments: 15626
If you have done your hurricane kits yet, I hope you haven't left it to late.

Goodnight all
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Quoting ElConando:


Oh Goody... meh
I don't like it either, but everything I'm looking at would coincide with what he is saying.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
ahumado..... I hear ya. I hope you are right. I am not a nice person when the A/C is out!
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Quoting cchsweatherman:
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.
I agree 100%.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting scott39:
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!


exactly what I am afraid of!!
Member Since: Posts: Comments:
Quoting cchsweatherman:
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.


Oh Goody... meh
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Opinions are not a FORECAST.

Member Since: July 3, 2005 Posts: 421 Comments: 127702
Quoting HoustonTxGal:


I too am in Spring.. howdy neighbor!


Posted on the prev thread right at the end in response to your comment about losing A/C everytime a big storm comes thru - Nah, HTG, ain't gonna happen. And I know this 'cause my standby generator was finally installed this week guaranteeing that Galveston, Fort Bend and Harris Counties will not see another major storm until I move out of the house. Thank you very much. It's just one of the services I provide to the public. I'm near Spring, too, btw.
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Quoting clwstmchasr:


I fairly comfortable with the track but I am with you on intensity. I don't think it will be hurricane before it hits SFlorida or the Keys but I do believe it will be a cane in the GOM. Admittedly, the NHC always has low confidence in intensity forecast and is usually very conservative as well.
I mentioned earlier today this thing will reach hurricane strength at some point I you can, check out the RGG loop and zoom in on its center.Link
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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.