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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Does anyone think the low in the pacific could affect southeast florida when and at what intensity
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404. Skyepony (Mod)
Tom Terry would call that a pain train in '04 (when the ITCZ was a little higher)

East coast sea breze is coming in. See it here. Mesocyclone barely west of me.. gotta check that out.
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.
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Quoting spathy:
Alex I am so looking forward to our friend the rainy season.
Its such an interesting phenomenon to watch.
Its my fav. time of year here.
During rainy season my neck gets a crick from looking up so often.
Its amazing in like a span of five minutes you look up sunny barely any clouds you look up again theres ominous clouds right on top of you its truly amazing!
Member Since: April 8, 2010 Posts: 15 Comments: 2572
You always know your getting close to Hurricane Season when on weather band they discontinue Gulf Stream System Information that's usually prepared midday on a daily basis.
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Quoting Jeff9641:


Seabreeze collision should happen later in the day.
Okay just telling him what im seeing and it looks like just pop up thunderstorms right now
Member Since: April 8, 2010 Posts: 15 Comments: 2572
when that starts hoing down,the SE seabreeze w/be colliding along the west coast of FL w/its seabreeze,I'm hoping for some fun T-storms this evening in my area!!!!
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394. myway
As the weekend approaches and many will be enjoying an extra day off, Please take a moment to remember the reason for Memorial Day. Take a moment to pay respects to the many soldiers that gave their lives for our country.

It is only because of them that we have the freedom to disagree and to question our leaders.

I personnaly can not put into words the gratitude and respect I have for all that have served us so well.
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Skye, That train has an impressive caboose.
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We have dark clouds in the area now about to storm any minute.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Quoting Skyepony:
Wave Train..
Have you seen the surface analysis, it looks insane.

12z Surface Analysis.


*This is likely due to the strong upward motion MJO we are currently under.
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Quoting spathy:
Alex
Is there any indication of a seabreeze line developing?
It looks so far like just random pops here no collision of breezes yet.
Not that i can see i see the same thing as you
Member Since: April 8, 2010 Posts: 15 Comments: 2572
388. Skyepony (Mod)
Wave Train..
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Quoting hydrus:
I believe your area runs a higher risk for a hit this year.jmo
Well thats comforting to know but i think the tampa shields will work again well hopefully.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
you are correct aspectre, a civilian should never salute anyone in the military. And the Commander In Chief does not outrank a civilian: in fact he work FOR the cilivian. The civilians are his boss.
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Blog Update

Hurricane Season Blog #6: Quick Update On 90E
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precipitable water available,1-2 inches



3-4 inches,i doubt,not impossible,but unlikely,imo
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Quoting alexhurricane1991:
Sunshine here in odessa north of tampa but there are some clouds around
I believe your area runs a higher risk for a hit this year.jmo
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Quoting Floodman:


Wow...312%?
Flood, do you know where to get the ECMWF model that predicts the storms? I can find the ECMWF model, but not the section that predicts the hurricanes..
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just messn w/you jeff
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photomunkey "The general population should be taught to salute our military, even enlisted men and women ... Isn't the rule 'when in doubt as to whether someone outranks you, you should salute'?"

I prefer "When in doubt, scream and shout."

1) If s/he hasn't done a military tour, a civilian hasn't earned the privilege to salute military personnel, or the flag for that matter. While it's heart-warming when kids do it, adults are expected to know better. And their salute is viewed as being either deliberately ignorant or deliberately insulting.

2) Saluting enlisted ranks is likely to getcha a "Don't do that, I work for a living."

3) Though official rules are somewhat different (or rather could be interpreted as different by martinets), the actual practice is to salute a superior officer in situations in which one civilian would normally break routine to give greeting to another.

4) No one in the military, and that includes the Commander-in-Chief, outranks a civilian.
Don't like it, move to Burma or NorthKorea or some other country ruled by drooling nutcases.
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There is a big cell west of us here in Martin county and I hope stays there.
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377. Skyepony (Mod)
Quoting nrtiwlnvragn:
348. Skyepony

What do you think NOAA will name the additional P3 next year, "cookie monster"?


Cookie Monster is Sesame Street & though Kermit the Frog was on Sesame Street, The Great Gonzo was Muppet (as so is Kermit & Miss Piggy) so I've got to go something purely Muppet..Maybe Fozzie Bear or Animal. Dr Masters could make it a poll & send his results to NOAA..lol.
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Just getting our first taste in Tallahassee of the usual Summer seabreeze "pop-up" showers as a result of the seabreeze interaction.....A severe pop up t-storm over Tally right now; first non-frontal one of the year....Tells me something, the Summer rain season is about to get going in earnest in the Florida/Gulf region, and, changing patterns, and lower shear, in the coming weeks in the Caribbean...Just in time for Memorial Day Weekend.....Mother Nature is amazing in terms of watching the Calendar...... :)
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Quoting spathy:
Miami
Look at those outflow lines.
That is one of the coolest things to watch.
Radar and coming at you.
Sunshine here in odessa north of tampa but there are some clouds around
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Quoting Hurricanes101:


Oh my you predicted possible strong storms, over Florida at the end of May?

Wow you should win a Nobel Prize *rolls eyes*

Have you offered anything productive lately? All you do is ride Jeff. What's the deal man. Take it easy.
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Most of the Caribbean is under very low shear and could support a major hurricane today
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Quoting Drakoen:
HWRF something over the extreme western Caribbea/Yucatan and into the GOM. Potentially a piece of energy from 90E:



According to that Satellite Picture doesnt it look lie 90E is giving us the finger?
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371. adb42
Just drawing attention to a subtropical midget, an after-season subtropical depression, named Joel by RSMC La Reunion in the southern Indian Ocean. This system, referred to as 98S, intensified to 45 knots south of Madagascar. It will be pulled south by a mid-latitude trough and will dissipate within 24-36 hours.

http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/anglais/index.html
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94˚F outside (Miami, FL).
Hasn't been that hot in a while, thank God for the A/C.
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jeff,feeeelings.....nothing more than feeeelings,don't be so richard simmons,its just a wx forecast!!!!;)
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looking like some isolated severe wx possible today in the panhandle area,as well as FL's SE coastline,maybe,maybe,this evening along Fl's west side,possibly even along the coast as a piece of energy arrives this evening thru tomorrow from the west:expect a wet day tomorrow for most of FL w/ 1/2-1inch totals,more possible w/heavier cells......today's priming the atmosphere for a wet day tomorrow!!
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361. IKE
Gulf fights for tourists in wake of spill...from CNN.

From the article...

"Hotel bookings in the Florida Panhandle are down about 30 percent -- and in some cases 50 percent -- compared with this time last year, said Carol Dover, president and CEO of the Florida Restaurant and Lodging Association.

Some hotels that have traditionally sold out on Memorial Day weekend are reporting dozens of rooms still empty for the holiday, she added."
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Quoting Jeff9641:


You can usually it rains around 4 or 5pm.
Yeah i know but we have things to do tomorrow and we probably wont be back till later.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
348. Skyepony

What do you think NOAA will name the additional P3 next year, "cookie monster"?
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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.