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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1607. xcool
SouthALWX YEAH.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
me toooo :D
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Quoting xcool:

ECMWF DO POOR JOB

IMO...

looks good to me.
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1604. xcool



Member Since: September 26, 2009 Posts: 2 Comments: 15684
1603. xcool

ECMWF DO POOR JOB

IMO...
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting xcool:
YAYY
ok
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1600. xcool
123 HERE COME
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1599. xcool
YAYY
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting xcool:
i'm wait on ecmwf

Me too.
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1597. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1596. xcool
;))))
Member Since: September 26, 2009 Posts: 2 Comments: 15684
On this day last year, we had TD#1.
The 2009 Atlantic Basin Activity

24 Invests
11 Depressions
9 Named Storms
3 Hurricanes
2 Major Hurricanes

90E moving NE. Wont last long over land.

Member Since: Posts: Comments:
1594. xcool
i'm wait on ecmwf
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1593. Grothar
Quoting weathersp:


See, it doesn't make sense...


Notice the low wind shear until it reached Southern Florida. After that very little could survive the shear over 30kts. The scenario moving the system up the coast is a little too early to tell that far out. The CMC is famous for these long incorrect forecast, although they do get it correct sometimes.
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1592. JLPR
Quoting weathersp:


See, it doesn't make sense...


Good point, that must be some good stuff the CMC is inhaling lol XD
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1591. Grothar
Quoting weathersp:


The only comfort I have in seeing that is that LAST year I refered to the CMC as "Constantly Making Cyclones"


Notice the disclaimer at the end of my entry. I agree.
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Quoting Grothar:


First image is CMC at 108 hours and the 2nd is at 132 hours. The CMC is usually a little over sometimes. Just posting!!!


See, it doesn't make sense...
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Quoting Orcasystems:



AOI

AOI

AOI

AOI

Humour in Comments


The Haloed one is back
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1588. xcool
lmaooo
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Weather456:


That presents a problem but they have to be resourceful. I managed to complete center fixes on 90L and 90E and estimated intensity within reasonable range using the multitude of other data available.

If that is the case, then we may not see the 18+ storms this year as we get back to the pre-1999 era.


I can count on two hands storms that would have not been named without quikscat such as Marco.
Member Since: Posts: Comments:
Quoting Grothar:


First image is CMC at 108 hours and the 2nd is at 132 hours. The CMC is usually a little over sometimes. Just posting!!!


The only comfort I have in seeing that is that LAST year I refered to the CMC as "Constantly Making Cyclones"
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1584. xcool
TampaSpin thanks..
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Just to let everyone know but, Xcool has his own blog area now on the site........thanks Xcool as you are all set up and ready to go.....have fun!
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1582. xcool
all about timeing...
Member Since: September 26, 2009 Posts: 2 Comments: 15684
i am calling it a nite gang. Good nite.
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The GFS is doing something similar....looks like things might get active in 8-10 days
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1579. xcool
LOLOL TAMP
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1578. Grothar
Quoting TampaSpin:


HOLLY Crap batman......geesh...i was afraid of this.


Come on, Robin, to the Bat Cave! There's not a moment to lose! - Batman

Hey Tampa, I only post them, I don't even know what they mean. Sorry I beat you to the map XCOOL!!!!!!!!
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Quoting Grothar:


HOLLY Crap batman......geesh...i was afraid of this.
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1576. Grothar


First image is CMC at 108 hours and the 2nd is at 132 hours. The CMC is usually a little over sometimes. Just posting!!!
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1575. xcool



so GFS AND NGP AND CMC .IN GOM..NEXT EWC
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1574. EricSFL
Good night xcool! don't play with the chongas. lol
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1573. Grothar
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1572. xcool
mmove ne
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1571. EricSFL
I believe 90E has relocated (or moved) further northeast closer to Guatemala's coast.
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1570. xcool
bigg time
Member Since: September 26, 2009 Posts: 2 Comments: 15684
The Caribbean is open for business.

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1568. xcool
in few mins
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1567. EricSFL
Quoting xcool:
i'm wait on cmc


When does it come out xcool?
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1566. xcool
i'm wait on cmc
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Grothar:
Have a good evening folks. Got to put on the "icy hot" on my hips, take the cholesterol medicine, hot towel on my neck, lift support for my knee. It takes us older folks a little longer to get ready for bed. Play nice tonight. If anything develops wake me up on Monday. Nite


Holy Crap!!!
Member Since: May 17, 2007 Posts: 0 Comments: 632
alright calling it a night see you guys tomorrow afternoon or evening.
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1563. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1562. Grothar
Have a good evening folks. Got to put on the "icy hot" on my hips, take the cholesterol medicine, hot towel on my neck, lift support for my knee. It takes us older folks a little longer to get ready for bed. Play nice tonight. If anything develops wake me up on Monday. Nite
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1561. EricSFL
zzzzzzz
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1560. xcool



Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting louisianaboy444:


Audrey! Oh Alex lol


Lol. Let's hope Queen Audry reigns supreme as the biggest, baddest June storm forever! I don't wanna be nowhere around when something knocks her off her throne. :)
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One of those 550 is my Great-Grandfather Frances Menard
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AOI

AOI

AOI

AOI

Humour in 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.

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