Loop Current Eddy cuts off; oil danger to Keys now greatly reduced

By: Dr. Jeff Masters , 2:24 PM GMT on May 28, 2010

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A major ocean current re-alignment is underway the Gulf of Mexico right now, and the new configuration that is developing greatly reduces the threat of oil entering the Loop Current and affecting the Florida Keys and U.S. East Coast. As I explain in my Loop Current Primer, the Loop Current is an ocean current that transports warm Caribbean water through the Yucatan Channel between Cuba and Mexico. The current flows northward into the Gulf of Mexico, then loops southeastward just south of the Florida Keys (where it is called the Florida Current), and past the western Bahamas. Here, the waters of the Loop Current flow northward along the U.S. coast and become the Gulf Stream. With current speeds of about 0.8 m/s, the Loop Current is one of the fastest currents in the Atlantic Ocean. Every 6 - 11 months, the top bulge of the Loop Current cuts off, forming a 250-mile diameter circular eddy in the middle of the Gulf of Mexico. This clockwise-spinning eddy is filled with warm water from the Loop Current, and is called a Loop Current Eddy. The main body of the Loop Current then takes a fairly direct eastward path from the Yucatan Channel to the Florida Keys.

Over the past two days, surface currents in the Gulf of Mexico have aligned to form a Loop Current Eddy, as seen in the analysis of surface currents done by the U.S. Navy (Figure 1, and see also a 30-day animation of the eddy forming.) It remains to be seen if the deep water currents have followed suit, and a stable Loop Current Eddy cannot exist until the deep water currents also cut off into a clockwise-rotating ring of water at depth. A NOAA Hurricane Hunter aircraft is out over the Gulf of Mexico today dropping expendable buoys and current probes to determine if a stable Loop Current Eddy has formed. Roffer's Ocean Fishing Forecast Service has a nice discussion on the Loop Current Eddy formation.


Figure 1. Comparison of surface currents in the Gulf of Mexico on May 19 (top) and May 27 (bottom) as simulated by the HYCOM model. On May 19, the Loop Current made a large northward loop into the Gulf, and was able to transport oil from the near the spill location southwards through the Keys. By May 27, this loop had cut off, and new oil moving southwards from the spill will now be trapped in the clockwise rotating Loop Current Eddy that is cut off from the Loop Current. Note on the west side of the Gulf of Mexico, off the coast of Texas, there is an old Loop Current Eddy that cut off from the Loop Current in July 2009. This eddy cut off in the same location as this week's eddy, and has drifted west-southwestward at 3 - 5 km per day over the past ten months. Image credit: U.S. Navy.

If the eddy does remain in place, it will greatly reduce the chances of oil making it to Cuba, the Florida Keys, and beyond. Any oil moving southwards from the spill location will now become entrained in the eddy, and will move in a 250 mile-wide clockwise circle in the east-central Gulf of Mexico. A small portion the oil will get shed away from the eddy's periphery and make it into the Loop Current and waters surrounding the eddy, but the concentrations of oil doing so will be small. Keep in mind, though, that during the first 1 - 2 months that a Loop Current Eddy forms, it is common for the eddy to exchange substantial amounts of water with the Loop Current, and in some cases get re-absorbed into the Loop Current. A 1-year animation of the Loop Current shows that the last Loop Current Eddy, which cut off in mid-July 2009, experienced a 2-week period in early August when it re-attached to the Loop Current. A significant portion of any oil entering the eddy during a period of re-attachment will be able to enter the Loop Current and flow past the Keys.

One bad result of the eddy breaking off is that now we have an extra source of heat energy for passing hurricanes during the upcoming hurricane season. Loop Current eddies have high-temperature water that extends to great depth, and hurricanes passing over such eddies often undergo rapid intensification. Hurricanes Katrina and Rita of 2005 both underwent rapid intensification as they passed over warm Loop Current eddies in 2005. The formation of a Loop Current Eddy during hurricane season means that a much greater portion of the Gulf of Mexico has deep, warm water capable of fueling rapid intensification of hurricanes.

Oil spill update
Light offshore northwesterly winds are expected to blow over the northern Gulf of Mexico today through Saturday, resulting decreased threats of oil to the Louisiana shore, according to the latest trajectory forecasts from NOAA. These offshore winds may be able to transport oil southwards into the Loop Current Eddy that just formed; a streamer of oil moving southeastward into the Loop Current Eddy is visible in yesterday's NASA MODIS imagery (Figure 2). Winds will shift to onshore out of the south on Saturday night, then shift to southwesterly by Tuesday. The long-range forecast from the GFS model indicates continued southwesterly winds all of next week. If this forecast verifies, we will see our greatest chances yet of significant amounts of oil reaching the beaches of Mississippi, Alabama, and the Florida Panhandle.


Figure 2. Visible satellite image of the Gulf of Mexico taken at 2:55pm EDT Thursday May 27, 2010, by the MODIS instrument on NASA's Aqua satellite. Thin streaks of oil can be seen moving southeast and then southwest around the eastern side of the new Loop Current Eddy. Image credit: NASA.

Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post Wednesday with answers to some of the common questions I get about the 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 trajectory forecasts
Deepwater Horizon Unified Command web site
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Surface current forecasts from NOAA's HYCOM model
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Central American disturbance
The Atlantic is currently quiet, with none of our reliable global forecast models predicting tropical cyclone development over the next 6 days. There is an area of disturbed weather (90E) just off the Pacific coast of Mexico that will be a major concern for southern Mexico and much of Central America over the next 3 - 4 days. The disturbance will bring heavy rains to Central America during the weekend, potentially bringing serious flooding rains to portions of Mexico, Guatemala, El Salvador, Honduras, and Nicaragua. NHC is giving the disturbance a high (>60% chance) of the disturbance developing into a tropical depression by Sunday. Wunderbloggers Weather456 and StormW have more on the tropics.


Figure 3. Satellite image of the Central American disturbance 90E this morning.

Join the "Hurricane Haven" with Dr. Jeff Masters: a new Internet radio show
Beginning next week, I'll be experimenting with a live 1-hour Internet radio show called "Hurricane Haven." The show will be aired at 4pm EDT on Tuesdays, with the first show June 1. Listeners will be able to call in and ask questions. Some topics I'll cover on the first show:

1) What's going on in the tropics right now
2) Preview of the coming hurricane season
3) How a hurricane might affect the oil spill
4) How the oil spill might affect a hurricane
5) New advancements in hurricane science presented at this month's AMS Conference on Hurricanes and Tropical Meteorology
6) Haiti's vulnerability to a hurricane this season

I hope you can tune in to the broadcast, which will be at http://www.wunderground.com/wxradio/wubroadcast.h tml. If not, the show will be recorded and stored as a podcast.

I'll be back with at least one update over the coming 3-day Memorial Day weekend. Have a great holiday!

Jeff Masters

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Quoting KEEPEROFTHEGATE:
your letting it go to your head relax
It's been a crazy day and we only have a TS in the EPAC. Imagine when we get the Major hurricanes in the Atlantic.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1956. pottery
Quoting PanhandleChuck:
Wow... I didn't realize how many hurricane experts there were. I wonder if they all crawled out from under the same bridge, or has there been a population explosion?

LOL. But we been waiting MONTHS for this!
We been through Volcanoes, Earthquakes, Tsunami's, Airplane crashes, all kinds of stuff.
This is the real thing, man.
heheheheh
Member Since: October 24, 2005 Posts: 0 Comments: 23080
1955. Dr3w
Good Morning all.
Does anyone believe that Agatha could make it's way into the Caribbean and redevelop there?
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Quoting scottsvb:



omg the strength of a tropical storm or even hurricane doesnt intenisfy steering currents. Do you think a Cat 4 or 5 Hurricane can crash a trough? MET 101 you will learn that there.
You don't understand what I'm saying. I'm not saying that steering currents are being "intensified" I'm saying that the "push" towards the Caribbean gets stronger as Agatha gets stronger.

1010-1000 MSLP steering currents


999-990 MSLP steering currents
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting IKE:


That's what I see from some models. ECMWF doesn't show anything...yet.


ECMWF is pretty reliable this time of year. I would of hoped it had something 3-4 days out..

At least we have something to look at for the next couple of days.
Member Since: January 22, 2006 Posts: 0 Comments: 1516
1952. hydrus
Quoting Hurricanes101:
I think what will happen is somewhat similar to Alma/Arthur

Agatha will make landfall and likely dissipate over Central America

Meanwhile its energy and the upward MJO very well could help create another system in the Caribbean or GOM
Makes sense to me, a lot of the models are pointing in that direction. Did you notice how central Canada is getting pounded over over again by huge thunderstorms? If it keeps up it will be on the news.
Member Since: Posts: Comments:


AOI

AOI

AOI

AOI

Humour in Comments
Member Since: October 1, 2007 Posts: 81 Comments: 26493
Quoting AussieStorm:

same as my thinking. it's circulation will get to disrupted to stay together.

The 8,000 ft mountains will shred the remnants of Agatha.

Granted, it is possible that whatever remnants survive may make it into the SW Caribbean or the Gulf of Mexico.
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Quoting StormW:
Good morning!


Good Morning! :)
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1948. JamesSA
I see we have a named storm in the Pacific. :-)
Member Since: August 17, 2009 Posts: 0 Comments: 579
1947. IKE
Quoting scottsvb:


That is the only possibility...:)


That's what I see from some models. ECMWF doesn't show anything...yet.
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1946. JamesSA
BP is now playing video recorded earlier and calling it "live" on the CNN feed. I just watched as they opened a media player window and clicked play on the screen. The clock shows 4:42 this morning on the video.
Member Since: August 17, 2009 Posts: 0 Comments: 579
Quoting MiamiHurricanes09:
Are you kidding me? Of course strength plays a role in the steering of a system. Keep in mind that there are layers of steering,

1010-1000 MSLP
999-990 MSLP
989-980 MSLP




omg the strength of a tropical storm or even hurricane doesnt intenisfy steering currents. Do you think a Cat 4 or 5 Hurricane can crash a trough? MET 101 you will learn that there.
Member Since: January 22, 2006 Posts: 0 Comments: 1516
Quoting PanhandleChuck:
Wow... I didn't realize how many hurricane experts there were. I wonder if they all crawled out from under the same bridge, or has there been a population explosion?


lol
Member Since: March 10, 2010 Posts: 1 Comments: 7233
1943. scott39
Its hard to believe that some people on here want a hurricane to hit them! yea, its exciting as it comes toward you, but it also destoys lives when it hits! Cmon, grow up!!
Member Since: June 13, 2009 Posts: 0 Comments: 6706
1942. KEEPEROFTHEGATE (Mod)
Quoting Jeff9641:
Another thing to not the GFS is beginning to latch onto the CMC which has been consistant run to run since Thursday. I told you guys this trough was going to pick this system up. I took a lot of crap for explaining this scenario earlier in the week when I disagreed with Dr. Masters. If your wrog I will call you out and state my reasons as why a situation is going to occur.
your letting it go to your head relax
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Quoting IKE:
If Agatha does dissipate over Central America then some energy from it is apparently left over in the extreme western Caribbean/eastern Yucatan, and as a trough swings into the eastern USA the end of next week, picks up some of what's left of her and pulls it NNE.

By then the shear in the GOM is forecast to lift. Probably adding rain to peninsula Florida.
You see IKE that I could believe.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
I think what will happen is somewhat similar to Alma/Arthur

Agatha will make landfall and likely dissipate over Central America

Meanwhile its energy and the upward MJO very well could help create another system in the Caribbean or GOM
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting IKE:
If Agatha does dissipate over Central America then some energy from it is apparently left over in the extreme western Caribbean/eastern Yucatan, and as a trough swings into the eastern USA the end of next week, picks up some of what's left of her and pulls it NNE.

By then the shear in the GOM is forecast to lift. Probably adding rain to peninsula Florida.


That is the only possibility...:)
Member Since: January 22, 2006 Posts: 0 Comments: 1516
Wow... I didn't realize how many hurricane experts there were. I wonder if they all crawled out from under the same bridge, or has there been a population explosion?
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Quoting scottsvb:


That is totally untrue.. lol who told ya that? Steering currents are "Not" affected by the strength of a system.. lol
Are you kidding me? Of course strength plays a role in the steering of a system. Keep in mind that there are layers of steering,

1010-1000 MSLP
999-990 MSLP
989-980 MSLP

Member Since: September 2, 2009 Posts: 130 Comments: 21032
The GOM can support a Tropical system with water SSTs around 80-84dg but the wind shear will be high north of 25N...Anything that the CMC imagines and the convective feedback computer problems of the GFS show are pretty slim..but wont rule anything out right now.
Member Since: January 22, 2006 Posts: 0 Comments: 1516
1933. QMiami
Guatemala having an unlucky streak a TS heading their way and last night one of their Volcanoes Pacaya erupted - killing a reporter and closing the airport
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1932. IKE
If Agatha does dissipate over Central America then some energy from it is apparently left over in the extreme western Caribbean/eastern Yucatan, and as a trough swings into the eastern USA the end of next week, picks up some of what's left of her and pulls it NNE.

By then the shear in the GOM is forecast to lift. Probably adding rain to peninsula Florida.
Member Since: Posts: Comments:
1930. pottery
Quoting Unfriendly:
It's nice having a scapegoat, isn't it? I mean, judging by the comments I've seen, it's almost as if Obama PERSONALLY flatulated in the oil resevoir thus setting off a massive methane explosion. And then ordered a US Navy Sub to torpedo the riser pipe.

Come off your high horse - Obama is being criticiszed because he is sitting president (amongst other political agendas), just as ANY OTHER president in office during such a disaster would be criticized. People with lesser intellects find the need to BLAME someone, just to get their anger over the situation out.

Keep in mind that with this crisis, it is the entire US Government's, and BP's, job to solve this crisis, not one man, and there is only so much a president can do. Take a look at an allowed executive orders list - it's not like he can say "OK, oil spill, please direct your flow directly towards the riser pipe.", or "Stay away from the coastline!".

Take a look at this from a LOGICAL and SCIENTIFIC standpoint, and don't let your emotional and/or biased opinions take over.


Very well said. Bravo!
Member Since: October 24, 2005 Posts: 0 Comments: 23080
Quoting Bordonaro:

I believe that TS Agatha will probably dissipate over the mountains of Guatemala. There will most likely be nothing left of her come Tuesday.

same as my thinking. it's circulation will get to disrupted to stay together.
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Quoting Jeff9641:
The latest NAM also begins to emerge this system into the gulf now as well. GFS and CMC are very similar but with one difference intensity. The CMC explodes this system in the gulf as it crosses Florida. Wunderkid I know you want a storm to hit you but the only track for this is NNE as trough is expected to pick this system up and shoot it NE along the SE US coast everybody from FL to NC will get rain from this system and I'm talking some serious rain.
Just as you want this system to hit you. C'mon think of it from my perspective, how do you expect a system to go over central America, the Yucatan, and then emerge into an area of relatively cool SSTs and 60 knot shear and expect to get hit by serious rain. I just have to completely disagree with you.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting MiamiHurricanes09:
Yes, but the stronger/deeper Agatha gets the more aggressive the steering currents are.


That is totally untrue.. lol who told ya that? Steering currents are "Not" affected by the strength of a system.. lol
Member Since: January 22, 2006 Posts: 0 Comments: 1516
Thank you MiamiHurricanes09 for explaining
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TROPICAL STORM AGATHA
11 am EDT Graphics Update
STORM TRACK:

ADVISORIES:
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Quoting scottsvb:


The steering currents are weak..but not strong enough to make it to the caymans. The mid-upper winds are, but not the movement.
Yes, but the stronger/deeper Agatha gets the more aggressive the steering currents are.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Ameister12:

That's good!

I believe that TS Agatha will probably dissipate over the mountains of Guatemala. There will most likely be nothing left of her come Tuesday.
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Quoting scottsvb:


It could make it to monday.. but you think it will surive a trip over the mountains of C America?
If it were to cross over Guatemala and then into the Caribbean, yes. But if models are showing that it's going to go over the Yucatan peninsula and then into the Gulf of Mexico, no.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
It's nice having a scapegoat, isn't it? I mean, judging by the comments I've seen, it's almost as if Obama PERSONALLY flatulated in the oil resevoir thus setting off a massive methane explosion. And then ordered a US Navy Sub to torpedo the riser pipe.

Come off your high horse - Obama is being criticiszed because he is sitting president (amongst other political agendas), just as ANY OTHER president in office during such a disaster would be criticized. People with lesser intellects find the need to BLAME someone, just to get their anger over the situation out.

Keep in mind that with this crisis, it is the entire US Government's, and BP's, job to solve this crisis, not one man, and there is only so much a president can do. Take a look at an allowed executive orders list - it's not like he can say "OK, oil spill, please direct your flow directly towards the riser pipe.", or "Stay away from the coastline!".

Take a look at this from a LOGICAL and SCIENTIFIC standpoint, and don't let your emotional and/or biased opinions take over.

Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
No, because steering currents are depicting movement towards the Caribbean sea.


The steering currents are weak..but not strong enough to make it to the caymans. The mid-upper winds are, but not the movement.
Member Since: January 22, 2006 Posts: 0 Comments: 1516
1917. scott39
Agatha looks like she may have a chance to get her toes in the BOC,and then "off with her head" in the GOM!
Member Since: June 13, 2009 Posts: 0 Comments: 6706
Quoting MiamiHurricanes09:
Disagree. Agatha should be making landfall on Monday as per the NHC. As for dissipating, we'll have to see where steering currents are at the particular time.


It could make it to monday.. but you think it will surive a trip over the mountains of C America?
Member Since: January 22, 2006 Posts: 0 Comments: 1516
Quoting scottsvb:


cause you live in the caymans? :)
No, because steering currents are depicting movement towards the Caribbean sea.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Bordonaro:
They fixed the NHC Graphic :O)


That's good!
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Quoting wunderkidcayman:
hey guys I am think that TD1-E/TS Agatha will re-emerge in the Gulf Of Honduras Just north of East Honduras and make its way more E-ENE


cause you live in the caymans? :)
Member Since: January 22, 2006 Posts: 0 Comments: 1516
Quoting scottsvb:
should make landfall in 18-36hrs. Should disapate by Monday.
Disagree. Agatha should be making landfall on Monday as per the NHC. As for dissipating, we'll have to see where steering currents are at the particular time.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
hey guys I am think that TD1-E/TS Agatha will re-emerge in the Gulf Of Honduras Just north of East Honduras and make its way more E-ENE
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They fixed the NHC Graphic :O)

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Agatha forecasted to become a 65 MPH TS in 24 hours.


Member Since: September 2, 2009 Posts: 130 Comments: 21032
should make landfall in 18-36hrs. Should disapate by Monday.
Member Since: January 22, 2006 Posts: 0 Comments: 1516
TS Agatha
Member Since: September 2, 2009 Posts: 130 Comments: 21032

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.