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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Its already well north of the projected path!
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Storm - How are conditions in the Gulf?
This thing isn't going to Go nuts in that warm water is it?
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NWS Brownsville on 98L flooding:

Up to 20 inches in the Rio Grande Basin?!?!
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Did anyone on this blog mention anything about flights being delayed or canceled out of MIA? I thought I saw something about flights, but now I can't find the post. Any help would be appreciated.
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Quoting louisianaboy444:
I think the weakness will close off pretty soon and it will resume its more Westward track....the Furthest North i see it heading is the Keys
Ok, if it stays on its slow NW motion for a couple more hours, and then resuming a WNW/W track south Dade is right in the middle.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
934. PensacolaDoug 6:37 PM GMT on July 22, 2010

Very interesting- pretty much in line with what I was thinking.
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Looking at the visible pics, I do believe the llc may become exposed this afternoon.
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TropicalDepressionThree was^heading toward SanSalvadorIsland,Bahamas landfall in ~11hours.
(Straightline^projection using its last 2 positions. Take with HUGE grain of salt)
Copy&paste 21.9N75.0W-22.3N74.9W, 22.3N74.9W-23.9N74.5W, BIX, TAM, 18.5N87W, 28.7N88.4W into the GreatCircleMapper
Shortest red line denotes the movement between last two positions. Below the map shows:
TD3 had a heading of 13.1degrees (~9.4degrees north of NorthNorthEast) while traveling
a distance of 28miles(~45kilometres) over 3hours at a speed of ~9mph(~15k/h),
and was 113miles(~182kilometres) away from the coast in the direction of its heading.

^ Straightline projections are not forecasts of what will happen in the future,
especially not for TropicalCyclones. They aftcast what has already happened.
* DeepwaterHorizon is marked at 28.7N88.4W
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Quoting nrtiwlnvragn:
18Z model update


Yikes! Looks like I am in the crosshair..
Member Since: July 5, 2008 Posts: 0 Comments: 254
Quoting BenBIogger:


Its kinda weather related.


I agree, but admin was on a tear that day and tossed me, they may not care today :)
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I think the weakness will close off pretty soon and it will resume its more Westward track....the Furthest North i see it heading is the Keys
Member Since: August 29, 2006 Posts: 22 Comments: 1352
958. unf97
Quoting StormHype:


Her loud pie hole will wake everyone in SOBE.


LOL.. TWC always sends her out there chasing storms. Abrams always seems to get so hyper when she is out there , as she showed covering Alex in South Padre Island a few weeks ago.
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957. xcool


18z
Member Since: September 26, 2009 Posts: 2 Comments: 15684
can i see the two from this AM be for we had TD 3 thanks
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955. Jax82
UNF97 and SSGuy I live right here in Jax Beach and I tell you my grass could use some good ole rain! The past week its been bone dry and hot. Seems like it rains inland and dies before it gets to my house. Cant complain about the sunshine though :)
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Quoting StormHype:


What you say makes no sense. The ridge is controlling the track. It is strengthening, driving the westward component of the path faster.


the storm is strengthening, moving NORTH WEST at the moment.. it's already outside of the cone..
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18Z model update


Member Since: September 23, 2005 Posts: 14 Comments: 11223
Dewey and DestinJeff....humor is fine. Personally, I think both of you have a great sense of humor, and that's welcome to make the blog more enjoyable. Just use common sense if/when a big cyclone is approaching in the coming months. This I learned from personal banning experience years ago.
.
.
What's never tolerated is misrepresenting the NHC.
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Quoting louisianaboy444:


It should not go that far north!
Where do you think it'll go?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Recon plane is there. It will get a fix on center and then track will be more certain.

By naked eye on satellite, looks to be getting organized with some spiral bands forming.

ULL is moving away to the West.
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Matter of time .... Thats Bonnie
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Quoting captainhunter:
Was supposed leave PC Beach to head over to see my mother for a couple days in Orange Beach, AL tomorrow and still plan to but am a little concerned about leaving the wife without a little more certainty as to track and intensity. I assume by tomorrow the models will have a real good grip on it?


Well, better at least.
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Quoting stormhunter23:
Did anyone notice 98L?
Looking way better than TD 3 /TS Bonnie


See the difference?


Soon to be Bonnie has a much better structure than that disturbance. Most noteably, a less broad, closed circulation. The problem it has is with shear, preventing the thunderstorms from encompassing the circulation center properly. I doubt this will be much more than a 55mph TS while crossing near or over South Florida.
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Quoting AlexEmmett:

why does this image give me the creeps lol

I know why..... But I ain't tellin'!
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C'mon Bonnie..

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I'm gonna enjoy whats left of a beautiful day after the marlins game ends. May not be one tomorrow whether it stays in the straights or not..
Member Since: September 6, 2009 Posts: 2 Comments: 3768
what should i expect in northern broward then if that would happen? also, if the thing really does have 50 mph winds, then it should be a hurricane when it reaches sfla, right?

No reason to look at "ifs". I live in Broward and am just going w/ what the NHC says.
I'm planning on a somewhat windy (at times) and stormy day....nothing more.
If the track changes, NHC will let us know and will let you know what to expect in your area.
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it does look as though the ull is ripping soon to be t.s. bonnie. looking at wv.
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What he is seeing is something that several of us have noted this afternoon: There is a weakness that is temporary in the high pressure. If you look at any satellite imagery you can see that nothing is driving it west yet. Later, maybe....This will deviate the 5pm track somewhat.

Quoting StormHype:


What you say makes no sense. The ridge is controlling the track. It is strengthening, driving the westward component of the path faster.
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Quoting StormHype:


What you say makes no sense. The ridge is controlling the track. It is strengthening, driving the westward component of the path faster.
The LLC is gravitating towards the weakness for the time being, with a gradual turn to the WNW after the weakness dies out.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
The upper low is fading away to the west, doesn't seem like it's having much of an affect on 03L right now. I would put landfall in southern/central Dade county, so a shift towards the right in the 5PM cone is likely.


It should not go that far north!
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting neonlazer:
Thought I would post this for Patrap :)
Hurricane man!

Hurricane Prep 2010


For NOLA, he should be packing a 9mm on each side as well.
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Quoting InTheCone:


You might want to pull that, I got a ban for posting it last year when it was busy!


Its kinda weather related.
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Here's JB's take on the tropics this afternoon.



THURSDAY 1 PM
I DONT AGREE WITH TPC.

That is an almost impossible track to maintain this. The path south of Florida bucks right into the shear for one and for two is well south of where this is now. This should be named Bonnie, because it has had tropical storm conditions for 2 days northeast of it and has a closed rotary circulation. But there should be little weather in the keys out of this, as the center passes near Miami and the worst weather will be Miami to Ft Pierce.

And I dont think it will be stronger in the gulf wind wise than it is in Florida. The fact it its forming on the north side of the ellipse of low pressure that is moving across. The center will weaken over land and the southern end of it may then be what you can track through the gulf as the lowest pressure.

Keep in mind the further north path is a better one for intensification but ( or put it this way, organization). But I expect TPC to have to adjust the track north to my way of thinking. That path wont work as you wont get it to go there and keep in together given the parameters involved.

The system in the southwest gulf is hustling its way toward a storm, but will go ashore and unless it stalls TPC will not do much with that given their track record. This could be a disaster in Mexico though with rain as the improving dynamics mean it will carry itself well until it gets into the mountains and should be treated as a dying hurricane rain wise, rather than a disturbance.

Notice what is going on folks... the upper pattern in the tropics is changing rapidly with smaller closed lows and ridges between now taking over and backing west. Look out, the track race when it starts will leave the feint of heart by the road. This is not yet the start, just the upward pulse of the MJO, but its coming.

ciao for now *****
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Quoting unf97:


You are welcome! BTW SSIGuy, another scorcher today here in Jax. LOL.. Like a broken record. High expected around 96 degrees. We may get a break in the heat tomorrow and early Saturday as some spokes of energy coming through on the easterly flow from the Atlantic on the outer fringes of soon to be T.S. Bonnie brings NE FL some rain.


Hi Unf - in PV Beach here - I certainly do hope we get some rain from this TS up here in North Florida. All the rain has been going to Jax/Atl Beach or St. Augustine lately, and none here where I live. My yard looks like a Utah desert!

BTW - my daughter will be at UNF in the fall semester...
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Quoting BenBIogger:

Had it bookmarked for some random reason...


You might want to pull that, I got a ban for posting it last year when it was busy!
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Quoting dwpearson:
Anyone have a link to the live plane data

diddo
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Afternoon everybody.

Here's Baha's Storm Progress Report #1 for TD3 / Future TS Bonnie

2:30 p.m. 22 July 2010

Weather here in the SW quadrant of New Providence has begun to deteriorate in advance of the passage of TD 3 to the south. The storm is currently centred about 50 miles east of Duncan Town in the Ragged Island Range of the Bahamas and about 250 miles southeast of New Providence.

Early cloud cover moved in around 12:30 this afternoon, and some rain began to fall in the centre of the island around 1:20 p.m. On the northwest coast near the Cable Beach strip, it was overcast still not raining as late as 1:45 p.m. Inland, a rainsquall drenched the Blue Hill and Carmichael Road areas. At 2:00 p.m. winds were steady from the NE at 14 mph, but higher gusts have been experienced, with some easterly winds seen.

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Quoting kingzfan104:
what should i expect in northern broward then if that would happen? also, if the thing really does have 50 mph winds, then it should be a hurricane when it reaches sfla, right?
Up there you should be expecting some squalls and some sporadic gusty winds. Rely on your local NWS for better information.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
876. Hardcoreweather2010 6:28 PM GMT on July 22, 2010
Mexico is going to get slammed with rain again..
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923. unf97
Quoting StSimonsIslandGAGuy:



I wish it would bring rain.

This week has not been pleasant. We spent 72 hours in the 80s, from Sunday morning to Wednesday morning, day and night. Now it's 90. Yay. Dewpoint 75. No rain in 11 days.


Yeah, it has been an unusually hot and dry summer in NE FL and SE GA. We can thank strong High pressure over the Southern CONUS for that. Howeever, I think we will see the patttern shift in August as the typical setup for the Azores/Bermuda High will become better established. That is when we will really watch these tropical cyclones(CV storms) threaten the SEUS and East Coast as we head into the peak time of hurricane season.
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Quoting MiamiHurricanes09:
The upper low is fading away to the west, doesn't seem like it's having much of an affect on 03L right now. I would put landfall in southern/central Dade county, so a shift towards the right in the 5PM is likely.


What you say makes no sense. The ridge is controlling the track. It is strengthening, driving the westward component of the path faster.
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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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