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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it looks like on sat that the mlc is coming ashore near the mx/guat border,w/the llc being left behind a bit,definately not a vertically stacked system right now,its gotton to close to the sts already!!!
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2355. Drakoen
This microwave imagery from an hour an a half ago shows the system just off shore. May the station reporting the northerly winds is something locally influenced...


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From the Oil Drum:

"the next dog and pony show will be

1- LMRP cap .......another good sounding solution but the HC's leakage will significantly increase during this process when the riser is cut .....and this will make for very bad TV viewing ....this will actually combine the leaks (rmbr BP has been clever ....no single shot exists anywhere on the MSM which shows all the leaks in a concurrent view .......its always the dang ROV on top of the BOP showing the leaking mud ).....LMRP cap will make for bad TV viewing by combining leaks into a big leak so the perspective on the leak will be better than what BP has show so far.....RMBR BAD TV this process -- but buys a week for BP

2- putting another BOP on the existing BOP ....this will make for fantastic TV viewing .....a huge piece of equipment ...many pipes and odd shapes ......beautiful TV right here .....but cannot work since there is no way BP can risk a hot approach on this ....the risk -reward ratios can never be favorable no matter how you dress the figures in this case.....there is DP string in there ...you can bet the horse and the stable BP knows where and how long...excellent TV and buys BP another week
"
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2352. xcool
hey hey
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Skyepony,have the remains of Bandu turned into a wave as I see a big blob in eastcentralafrica or all of Bandu evaporated with the dry air of the dessert?
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Quoting StSimonsIslandGAGuy:


That mystery should soon be solved Drakoen!
Agreed.
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Ike, even so if nothing forms in the Atlantic. We are still watching cross over systems much like what Agatha appears to be. The CV waves that are coming off appear to be still embedded in the conversion zone, so we have to wait on that also.
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2347. Drakoen
That station is reporting northerly winds. If the system was west of that location then it should be reporting winds out of the south.
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Quoting Drakoen:
Wonder if Agatha is making landfall:

I doubt it. The NHC says it will make landfall early Monday morning.
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My one item on Agatha is this. We all saw how the mess over by the Yucatan blew up rapidly two weeks ago. Looking at the Nogaps track, could that possibly happen with a storm system that tracks over from the Pacific into the bay of Campeche or into the Yucatan channel?
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2343. hydrus
Quoting Drakoen:
Wonder if Agatha is making landfall:

It sure looks like it.
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2342. Drakoen
Wonder if Agatha is making landfall:

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2341. hydrus
Quoting atmoaggie:
Looks like we can expect Agatha to spend a solid couple of days over land, little of it low-land marsh. Should emerge just about destroyed. Regenerating depends on conditions being right enough to develop a new system.

The tough one is how much vorticity will remain.

If Agatha does emerge into the Gulf or Caribbean and the vertical shear slows down over the region, I give it a 70% chance of regenerating into a tropical storm.jmo
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Broad surface trough forming just north of hispaniola!!!
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2339. Walshy
Quoting StSimonsIslandGAGuy:
Well regeneration is not impossible. But I put the odds of Agatha becoming the first named storm of the season in the Atlantic basin at less than 10%



That is what im thinking too. Maybe some left over moisture about it.



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According to the New York Times, a third attempt at the Junk Shot has failed. SOunds like the whole Top Kill is a fail. BP already knew by Friday that the project has failed. On CNN someone suggested that they wanted to wait till the weekend to avoid BP's stock from crashing.

Jerks.
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Agatha will make landfall within 6-18hrs
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Quoting kimoskee:



No, no, no, no sandwich. it's a pudding. I serve it warm with golden syrup on top and whipped cream. Trust me, you gotta taste it!


Like many times in life, its not the way you say it but the way it sounds. Pottery, I completely understand where you are coming from with the comments.
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2335. Walshy
Hurricane Preparedness Day in North Carolina.



Snowing in Montana today too by the way.

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2333. pottery
Quoting WaterWitch11:
shots of grand marnier with a fruit chaser.

pottery i have a question. is the view of the oil spill at a different location? it looks as though it is a mud/oil mix.

The feed on CNN is not from the top of the BOP,
It is from another leak in the riser that was buried in the mud, between the BOP and the end where the "insertion tube' is.
Thats how I see it,,
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2332. Skyepony (Mod)
Not that I think it has much chance of happening~ I can see one thing on Agatha's side that could intensify it near FL & that is the persistent lower pressure here. Been meaning to double check my PWS which has been 1004mb-1006mb for days til I saw the MSLP anomaly for the week posted..
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shots of grand marnier with a fruit chaser.

pottery i have a question. is the view of the oil spill at a different location? it looks as though it is a mud/oil mix.
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2330. pottery
Quoting WaterWitch11:
fruit soaked in alcohol. yummy! just had to get in another before june 1st. gonna try some white peaches in triple sec or grand marnier today!

Now, this sounds more up-my-street, frankly.
Actually, you could probably leave all the fruit out!
And the bread too.
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Yes sir! LOL
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Quoting StSimonsIslandGAGuy:
Agatha is no mystery. It appears unlikely that it will be able to survive its trek across Central America---and even if it does, it will be shredded and take a long time to reorganize. And that is good news.


Im not agree 100% depends how strong reach the coast and direction will take.
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fruit soaked in alcohol. yummy! just had to get in another before june 1st. gonna try some white peaches in triple sec or grand marnier today!
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2325. pottery
Quoting kimoskee:



No, no, no, no sandwich. it's a pudding. I serve it warm with golden syrup on top and whipped cream. Trust me, you gotta taste it!

Yeah, I know what it is. But I pass!
Anyway, we better get back to the weather, before we get into trouble....
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meh 2300posts in 28hours. That's only 82messages per hour that ya hafta sift through.
Wait until HurricaneSeason actually fires up...
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Looking at live feed. I think they have managed to turn it in to a oil volcano for sure.
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2322. KEEPEROFTHEGATE (Mod)
Quoting StSimonsIslandGAGuy:
Agatha is no mystery. It appears unlikely that it will be able to survive its trek across Central America---and even if it does, it will be shredded and take a long time to reorganize. And that is good news.
yes it is
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Quoting pottery:

OK, I hear you. But the very IDEA puts me off.
Like banana sandwiches.........
WHY???



No, no, no, no sandwich. it's a pudding. I serve it warm with golden syrup on top and whipped cream. Trust me, you gotta taste it!
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Quoting KEEPEROFTHEGATE:
theres a point before the nines nrt


Oops, misinterpreted. Though you meant .999 not already expressed in percent.
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2318. pottery
Quoting kimoskee:


Honey, you haven't had bread pudding until you've had my friend's bread pudding. We call it the "orgasmic bread pudding"! She uses fresh hardo bread, cream, golden raisins soaked in rum... I'm gaining pounds just thinking about it!!! DELICIOUS!!!!

OK, I hear you. But the very IDEA puts me off.
Like banana sandwiches.........
WHY???
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Quoting FIU2010:
afternoon adrian, how are ya? it's shapping uup to be a bad year for us, ain't it?


Hey FIU2010! It will all depend on the particular set-up at the time. A few days ago i was chatting with tpc forecaster todd kimberlain while i was working on some marine obs about how insane the ECMWF forecast of SLP in the tropics.
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Looks like Agatha is about to make landfall in the next 12-24hrs unless she pulls back from the coast in the weak steering flow. The flow though has increase some, maybe from the stronger Agatha and the ridging building in over the southern carribean. If this is the case.. 6-12hr timeframe wouldn't be a surpise.
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2314. KEEPEROFTHEGATE (Mod)
theres a point before the nines nrt
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Hmm, dead center of a just-issued severe thunderstorm watch.



Going to the pool anyway...L8R
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Quoting pottery:
OK thanks.
I wondered if the wave would remain over SA. Glad you think so as well.


Yea it is expected to remain over SA.
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Quoting sporteguy03:


I think it might be because of the orographic lift maybe enhancing the rainfall?


Correct




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2310. KEEPEROFTHEGATE (Mod)
Quoting sporteguy03:


I think it might be because of the orographic lift maybe enhancing the rainfall?
nice to see ya 03
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Quoting KEEPEROFTHEGATE:
.999


99.9% ? I think you meant .001
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Quoting pottery:

Oh, I dont know. What about bread pudding. And porridge. And, er, well never mind...


Honey, you haven't had bread pudding until you've had my friend's bread pudding. We call it the "orgasmic bread pudding"! She uses fresh hardo bread, cream, golden raisins soaked in rum... I'm gaining pounds just thinking about it!!! DELICIOUS!!!!
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Looks like we can expect Agatha to spend a solid couple of days over land, little of it low-land marsh. Should emerge just about destroyed. Regenerating depends on conditions being right enough to develop a new system.

The tough one is how much vorticity will remain.

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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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