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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2010 Atlantic Hurricane Season Forecast

Reserve commentary in my blog
Member Since: Posts: Comments:
Quoting ElConando:


I'll be releasing a JFV landfall prediction blog for every storm this season. 50% of the time my prediction will fail 100% of the time.


So sort of a JFV/Yogi Berra feature? OUTSTANDING!
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505. xcool
haha
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Outside.

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Quoting Floodman:


Because he's not a fool?


I'll be releasing a JFV landfall prediction blog for every storm this season. 50% of the time my prediction will fail 100% of the time.
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call me a wishcaster, but I'm with CMC on 90E

the system is strenthening, and if the system gets named, the upper level flow to its north will eventually begin to carry it to the EAST/NE
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Quoting Hurricanes101:
90E looks like it is moving NNE
Current motion is NE at 2 MPH.
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I briefly touched on the potential for landfall under the NAO section of the outlook; it was not embellished for obvious reasons.
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90E looks like it is moving NNE
Member Since: March 10, 2010 Posts: 1 Comments: 7874
MiamiHurricanes09 18z 90E Forecast Cone.

*I will be releasing these throughout the season.

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Quoting FIU2010:
Drak, how come you didn't point out potential landfall locations on your outlook?


Because he's not a fool?
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no forecaster here
has more knowledge
than Drak

and none are
his equal at
presentation
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Quoting MiamiHurricanes09:
coming together quite nicely
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I wonder what up with the models I would laugh so hard if it ends up comming through between cayman and Jamaica when the models are saying SE GOM and florida keys well we will know more when it crosses over within the next 24-48/72 hours or something of the sort
Member Since: June 13, 2009 Posts: 2 Comments: 12712
488. IKE
Quoting hydrus:
You want to see something interesting? Look at the NOGAPS model. It has a hurricane hitting Nicaragua on June 5.


12Z NOGAPS
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487. xcool
CRAZY NGP
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting MiamiHurricanes09:
Interesting to see.
You want to see something interesting? Look at the NOGAPS model. It has a hurricane hitting Nicaragua on June 5.
Member Since: September 27, 2007 Posts: 1 Comments: 22314
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Quoting Drakoen:
RAMSDIS satellite imagery shows a well-defined low pressure center with 90E near 12.8N 94.5W
I agree. That's the current COC.
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Thank u jeff9641 sorry to hear bout gsry coleman snyone know how it happenend
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EP, 90, 2010052818, , BEST, 0, 128N, 945W, 30, 1005, LO
Member Since: March 10, 2010 Posts: 1 Comments: 7874
RAMSDIS satellite imagery shows a well-defined low pressure center with 90E near 12.8N 94.5W
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Quoting nrtiwlnvragn:
BAMs now taking the Yucatan route.




Interesting to see.
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Quoting Drakoen:


28/1745 UTC 13.4N 94.7W T1.5/1.5 90E -- East Pacific
That's enough to be labeled as a TD.
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Quoting Skyepony:
12Z LGEM is on board with CMC. 12z ECMWF isn't.


GEM and CMC are one of the same.
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BAMs now taking the Yucatan route.




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i want to know what james carville has to say about obama's visit. i hope obama is speaking with the people of louisiana.
Member Since: August 11, 2008 Posts: 3 Comments: 1712
Quoting Skyepony:
12Z LGEM is on board with CMC. 12z ECMWF isn't.


That is the CMC...
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isnt the current shear over the Gulf n northern carribean running like 40+ mph??
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Quoting nrtiwlnvragn:
EP 90 2010052818 BEST 0 128N 945W 30 1005 LO


Ships Text


28/1745 UTC 13.4N 94.7W T1.5/1.5 90E -- East Pacific
Member Since: Posts: Comments:
EP, 90, 2010052818, , BEST, 0, 128N, 945W, 30, 1005, LO,

Judging from this and the latest ASCAT we should have TD 1-E in the next 12 hours.
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Quoting kimoskee:


Find him??? LOL. He's probably somewhere is South America drinking champagne. Very, very sad situtation.

Thats what I thought...
Bad business.
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469. Skyepony (Mod)
12Z LGEM is on board with CMC. 12z ECMWF isn't.
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Drak...on your page I see pics of andrew , tip and what is the other storm u have there?? is that wilma???
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Quoting wunderkidcayman:
guys if 90-E can not intensify above TD then we will likely see development in the Caribbean side just in between honduras and belize and shoots toward the caymans and cuba going into the Bahamas and a bit north till it hit the Sub-tropic jet


Hello,
Difficult to see, but a little chance to pass to Caribbean.
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EP 90 2010052818 BEST 0 128N 945W 30 1005 LO


Ships Text
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Quoting pottery:

Did they find Dudus?


Find him??? LOL. He's probably somewhere is South America drinking champagne. Very, very sad situtation.
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What a fantastic outlook Drakoen has just posted. Many at the NHC can't write like that. Drakoen I applaud you.
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Quoting Unfriendly:
WOW - just had a rotational t-storm in frostburg, MD, elevation 2000 feet on top of a mountain. Quarter sized hail, lightning ~5 seconds, VIL of 62, and a top of 37k feet. Don't get too many like that around here.


Yep, several reports of 0.75" hail, one of 1" hail and "trees bent down" in Frostburg.

A bit southwest in Midlothian there is a report of 1.75" hail that was a mix of golf-ball and penny-sized hail.

Another storm building to your west.
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I was trying to quote and could not could it be that I am on my blackberry
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Currently, the weather radio broadcast you can here on the website's live severe weather webcam is originating from my helmet.

I stuffed the radio inside. What you're hearing is the bluetooth connection to the computer that is broadcasting the webcam.

Tell me my system design isn't top drawer!! :)

It's about 4 hours and 15 minutes of uninterrupted broadcast. :P
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459. xcool



Member Since: September 26, 2009 Posts: 2 Comments: 15684
guys if 90-E can not intensify above TD then we will likely see development in the Caribbean side just in between honduras and belize and shoots toward the caymans and cuba going into the Bahamas and a bit north till it hit the Sub-tropic jet
Member Since: June 13, 2009 Posts: 2 Comments: 12712
457. IKE
6-10 day temps...




6-10 day precip...

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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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