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 AussieStorm:

i would downgrade it to a TD
It has been downgraded already.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Quoting extreme236:
Why must JFV come back every season?

Cause he can't stay away from this place. He likes causing trouble and conflict.
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Quoting extreme236:
Why must JFV come back every season?


Good to see you back Extreme!
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3552. xcool
btwntx08 COME ON NOW YOU IT'S A BEAUTIFUL DAY IN neighborhooOOOO LMAO LMAO
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting AussieStorm:

i would downgrade it to a TD


It already is a TD
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Quoting extreme236:
Why must JFV come back every season?


To remind us every year that the ignore button still exist.
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Quoting xcool:



I HAVE HOPES

i would downgrade it to a TD
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Quoting xcool:
KoritheMan NONO .I SAY HOPE MEAN FOR FIU2010


Ah, okay. Just checking.
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3546. scott39
By this time tomorrow it will be------ Agatha who????
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Why must JFV come back every season?
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Quoting FIU2010:
they could redevelop, alex.
Nope not seeing it sorry wont have enough time to redevelop before going into the buzzsaw shear which is in the gulf.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3542. xcool
KoritheMan NONO .I SAY HOPE MEAN FOR FIU2010
Member Since: September 26, 2009 Posts: 2 Comments: 15626
3541. EricSFL
Quoting guygee:
It is the bigot who picks on people for speaking Spanish here. If you don't want to learn, just open a tab on Babel Fish or equivalent.

I am glad we have people from all over the world posting here, whatever the language. More weather-watchers from different places can only be a good thing on this blog.
Sheesh! Sorry to have to state the obvious...


It is not about speaking Spanish, it's about what is beeing said in Spanish.
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Quoting altesticstorm10:
Bah gawd it must suck to be JFV/tropicalamanda/WeatherStudent/FIU2010...I mean, I'm a troll in my own right, yada since 2006 . . . but getting that much attention is definately lulzy and disgraceful


OK, but notice you are starting trouble right now by saying that. You and everyone else just need to stop giving him attention. It's getting annoying. I'm in high school too and I don't act as immature as some of you. That's really all there is to say about that.

Anyways, it looks like Agatha may drench Florida in rain.
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Quoting StSimonsIslandGAGuy:
Google translate is amusing.

More than one permabanned troll is back.

Agatha is looking better over land than water. If it wasn't heading into mountains and the convection centered better, I'd wonder about her pulling a Fay.

I hear ya
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3537. xcool
I'm going SIT backing & drink,MY BEER ..WAIT ON FORECAST MODELS.
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting xcool:



I HAVE HOPES


Hopes? You want it to survive the crossing?
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Quoting xcool:



I HAVE HOPES
I think it wont last long its already weakening rapidly.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3532. guygee
It is the bigot who picks on people for speaking Spanish here. If you don't want to learn, just open a tab on Babel Fish or equivalent.

I am glad we have people from all over the world posting here, whatever the language. More weather-watchers from different places can only be a good thing on this blog.
Sheesh! Sorry to have to state the obvious...
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3531. EricSFL
Agahtha seems, whats the word... discombobulated?
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so where do you guys think that TD Agatha's COC is
Member Since: June 13, 2009 Posts: 2 Comments: 11233
3528. xcool



I HAVE HOPES
Member Since: September 26, 2009 Posts: 2 Comments: 15626
I see JFV/TropicalAmanda/PresidentalElection/1000Windows/Weatherstudent/FIU2010 has made his presence known tonight. lol
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3526. bappit
Quoting xcool:



LOW SHEAR CHANGE


There is still a lot of shear. Average the low and high shear areas together and they might even out.
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Quoting FIU2010:
:). aggy is looking promising
Aggy is looking pretty bad too me the coc is to the left of the heviest storms.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
How is aggy looking promising?

The flooding in Central America could be devastating
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3522. xcool
btwntx08 LMAOO
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting intunewindchime:
why is the blog being bombarded by trolls?????????????????????????????????????

cause they always come out at this time of year and try to disrupt the blog and put it into conflict.
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Quoting FIU2010:
thank you for understanding, SF. naw tim, plz dont say that,w e're good friends for forever, besides he had called me a cancer, a cancer, would you take a remmark like that lightly and not defend yourself? i wouldn't think so.


WHAT! Don't say we are good friends forever......didn't say i was a good friend. See ya!
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3512. xcool
I'M TO OLD FORTHIS HAHA
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting FIU2010:
thank you for understanding, SF. naw tim, plz dont say that,w e're good friends for forever, besides he had called me a cancer, a cancer, would you take a remmark like that lightly and not defend yourself? i wouldn't think so.

I hope you have changed for the better. But you know good and well that your past actions under other handles were VERY inappropriate. We are giving you another chance, but that comes with A) accepting the jokes on you and B) understanding that not everyone likes you.
You seem much nicer and less naive now, and I hope that is the case, but past transgression can be forgiven but not forgotten and you need to know that and live with it.
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Quoting FIU2010:


y tu, no? el que me ofende a mi, yo lo ofendere para tras, tu no harias lo mismo? eso no es justo, ese degenerado me llamo un cancer, un CANCER, TU sabes que significa eso? en fin, olvidalo, eso es castigo por dios. tu me caes mas o menos, no me sigues molestando, para que no tenga que reportarte yo a ti tambien.


and you, no? that offends me me, I take offense to after, you would not do the same? that's not fair, that I call myself a cancer degenerate, a CANCER, YOU know what that means? Finally, forget it, that is punishment by God. I like your more or less, there still bothering me, so I do not have to report you to you too
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About

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