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 scott39:
Is 90E even a threat to the SE USA if it goes in that direction? Seeing how wind shear will blow it apart?


it has an anti cyclone on it..
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Recent ASCAT


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Run the water vapor imagery and you can see everything to the north of 90E is sliding eastward

Link
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Quoting FloridaTigers:
Can anyone post the vorticity maps?
thier on crown weather.com
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Can anyone post the vorticity maps?
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Is 90E even a threat to the SE USA if it goes in that direction? Seeing how wind shear will blow it apart?
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Quoting IKE:
Td1E at the 800pm update well 500pm over there
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Quoting MiamiHurricanes09:
19:45 UTC - 3:45 PM EDT


Deep convection building over the center
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549. IKE
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Quoting Chicklit:
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. From JM's Blog

... as if we needed one more positive for development this season ...
That alone should raise your major hurricane numbers by 1.
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Quoting MiamiHurricanes09:
If it strengthens to a pressure below 999 MSLP expect 90E to be directed towards Jamaica, as per 18z CIMSS steering currents.


If that happens there will be serious problems here.
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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. From JM's Blog

... as if we needed one more positive for development this season ...
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19:45 UTC - 3:45 PM EDT
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Quoting WaterWitch11:
please tell me obama is going to visit other areas other than grand isle?!?

Nope, tis but a "show visit".
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I believe we have EPAC TD-1. Decent outflow, pressure dropping.
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Quoting Jeff9641:
Don't be surprised if this is a TD or TS right now. We will see this upgraded very soon maybe in a hour.
I think it will be upgraded to TD status at 8:00PM EDT. Keep in mind that at 8:00PM here it's 5:00 PM over there.
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Quoting kanc2001:


stupid internet filter blocks mediafire here at work.


Mail for you
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Quoting kmanislander:
Hi Drak,

I just read your forecast for 2010 and would like to congratulate you on a very nice presentation. It made for easy reading and touched on the material factors.

I really did enjoy it until I got to the numbers at the end !. It is what I would call a scorpion report: the sting is in the tail.

Good work.


I'm reading it right now looks great!
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Quoting kmanislander:
Hi Drak,

I just read your forecast for 2010 and would like to congratulate you on a very nice presentation. It made for easy reading and touched on the material factors.

I really did enjoy it until I got to the numbers at the end !. It is what I would call a scorpion report: the sting is in the tail.

Good work.


Thank You
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Quoting CybrTeddy:


Look how quickly the GOMEX warmed up! Its already above normal. For those who where thinking that the cold snap this winter was going to have any effect, think again.
Yup. Notice the below average equatorial Pacific and the above average Atlantic basin, mostly the African coast and the GOM.

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Quoting kmanislander:
Hi Drak,

I just read your forecast for 2010 and would like to congratulate you on a very nice presentation. It made for easy reading and touched on the material factors.

I really did enjoy it until I got to the numbers at the end !. It is what I would call a scorpion report: the sting is in the tail.

Good work.
Indeed. Scary ending though.
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DATE/TIME LAT LON CLASSIFICATION STORM 90E
28/1745 UTC 13.4N 94.7W T1.5/1.5 90E
28/1145 UTC 12.9N 95.2W T1.0/1.0 90E
28/0545 UTC 11.8N 95.8W T1.0/1.0 90E
27/2345 UTC 12.5N 96.4W TOO WEAK 90E
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Hi Drak,

I just read your forecast for 2010 and would like to congratulate you on a very nice presentation. It made for easy reading and touched on the material factors.

I really did enjoy it until I got to the numbers at the end !. It is what I would call a scorpion report: the sting is in the tail.

Good work.
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Quoting kanc2001:


stupid internet filter blocks mediafire here at work.


Sorry to hear
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Quoting Drakoen:
The stronger 90E becomes the more east it will go as it will be feeling the deep-layered trough.
If it strengthens to a pressure below 999 MSLP expect 90E to be directed towards Jamaica, as per 18z CIMSS steering currents.

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Quoting Stormchaser2007:


Look how quickly the GOMEX warmed up! Its already above normal. For those who where thinking that the cold snap this winter was going to have any effect, think again.
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Quoting Drakoen:
2010 Atlantic Hurricane Season Forecast

Reserve commentary in my blog


stupid internet filter blocks mediafire here at work.
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528. Skyepony (Mod)
Quoting Chucktown:


GEM and CMC are one of the same.


That is not true..yesterday they had a ~20 mile difference in their forecast error for 90E. Though some times they are similar, sometimes they aren't. GEM also runs a GLB & a REG.
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Quoting Jeff9641:
As I've been saying a more northern track is going to occur: the reason the trough moving in from out west. Will direct this to the SE US. This is why i went to school for meteorology. Now mind you I did switch and I got a degree in finance.


So are you with the CMC track?
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The stronger 90E becomes the more east it will go as it will be feeling the deep-layered trough.
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Quoting Stormchaser2007:
Poor fish in the Caribbean. They're probably being cooked by the water, lol.
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This should be a very interesting forecast for the next few days

Many variables in place here

Lots of questions too

How much will 90E intensify?

Where will it go?

How will all of this effect anything that tries to form over the Caribbean?

Could it be that 90E eventually is the entity that reforms over the Caribbean?

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Quoting Drakoen:
2010 Atlantic Hurricane Season Forecast


I'd like to read it.. but apparently you banned me from the blog (per the WU message) :-(
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XtremeStormJunkies Update:

The full-scale portable power test of the live severe webcam is now at 5 hours with no interruption in any service.

All bluetooth devices, which are operating on their own, internal batteries are still functioning well.

The webcam system (computer, cell phone, and wireless 3G broadband card) are still fully operational and running off the "main batt."

You can see the progress of this full-scale portable power test by going to our media call-out URL of 7674u.com

At five hours of operation, I'm now fully impressed with the bluetooth devices!
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Quoting Drakoen:


Wow thank you! I'll definitely take it into consideration. Good luck to your daughter as well.


I'm sure you will do well in their program but please remember; you gotta know your mathematical algorhythms before they will let you loose on forecasts....... :)
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I think TS watches and warnings should be issued along Guatemala tomorrow.
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IKE,

I previously said no on the CMC, I take it back. Its general track may be correct. The 18Z TVCN goes into the BOC, and the only reason I can think of why it does is the ECMWF.
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Quoting weathermanwannabe:
423. Drakoen 2:59 PM EDT on May 28, 2010

Nice work...You started out quite a bit cocky a few years ago but have matured quite a bit. Really excited to know you are going to FSU Met Program in the Fall and know how expensive school is and having to get through when you are away at College (My oldest Daughter starts at Yale this August). You have a lot of talent and let me extend this offer. I work in Downtown Tallhassee close to FSU. If you ever get low on funds while at FSU, and get a little hungry, please do not hesitate to e-mail me and I will gradly treat you to lunch or dinner and I mean that...I know a few of the Professors and Mets over there so please take me up on the offer.......Bet of luck to You this Fall....WW


Wow thank you! I'll definitely take it into consideration. Good luck to your daughter as well.
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20100528.1915.goes13.x.wv1km.90EINVEST.30kts

Last report 30kts up 5kt from before.
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Quoting ElConando:


/Anchorman :P


Stay Classy Miami :P
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well leo305 I am thinking more of a eastward track hitting cuba and as it is now in the E-Pac I expect at the most a TD on verge of TS makes landfall then come into the Caribbean and grow and be at the most a Mod. TS
Member Since: June 13, 2009 Posts: 2 Comments: 12712
Quoting ElConando:


/Anchorman :P


I'm older than you...oddly though, when I hear such verbal convolution it's JFV AND Berra that come to mind
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Quoting Floodman:


So sort of a JFV/Yogi Berra feature? OUTSTANDING!


/Anchorman :P
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We are going to get dumped on here in odessa north of tampa any minute winds are picking up i hear thunder and very dark skies.
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423. Drakoen 2:59 PM EDT on May 28, 2010

Nice work...You started out quite a bit cocky a few years ago but have matured quite a bit. Really excited to know you are going to FSU Met Program in the Fall and know how expensive school is and having to get through when you are away at College (My oldest Daughter starts at Yale this August). You have a lot of talent and let me extend this offer. I work in Downtown Tallhassee close to FSU. If you ever get low on funds while at FSU, and get a little hungry, please do not hesitate to e-mail me and I will gradly treat you to lunch or dinner and I mean that...I know a few of the Professors and Mets over there so please take me up on the offer.......Best of luck to You this Fall....WW
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2010 Atlantic Hurricane Season Forecast

Reserve commentary in my blog
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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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