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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And Alex, I'm sure I'll get a "nastygram" any minute...

Warm Regards,

That "chick formerly from GA"

Member Since: Posts: Comments:
Quoting melwerle:
Haven't posted much since I've been back in CA but been watching and reading.

Please exercise the ignore button...

That being said however, I am ready to "take one for the team" and get banned. It's really taking everything I have to NOT do it. But hey, if I do, I can just create 1,000 handles and come back.

Hope everyone stays safe this season...my thoughts are with all of you.

But hey...a hurricane COULD hit san diego right guys??? Hey, should I board up the house right now and get ready for the storm that's in Central America? I mean I heard that it could come this way...
LMAO!!!! LMAO!!!!
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3582 xcool "WT[[[[[ WT[[[[ THAT KIND CRAZYYYY"

On the one hand, high shear over the Gulf of Mexico, good.

On the other hand, temperatures are so high and the shear is so low in the Caribbean west of the LesserAntilles and south of the DominicanRepublic that that even a peanut butter sandwich should grow into a hurricane.
So what am I not seeing that makes a hurricane not there? Dryness ne plus ultra?
Member Since: Posts: Comments:
Haven't posted much since I've been back in CA but been watching and reading.

Please exercise the ignore button...

That being said however, I am ready to "take one for the team" and get banned. It's really taking everything I have to NOT do it. But hey, if I do, I can just create 1,000 handles and come back.

Hope everyone stays safe this season...my thoughts are with all of you.

But hey...a hurricane COULD hit san diego right guys??? Hey, should I board up the house right now and get ready for the storm that's in Central America? I mean I heard that it could come this way...
Member Since: Posts: Comments:
Quoting FloridaTigers:
Ladies and Gents, I would like to say that Janiel F. Vargas does not speak for us Southern Floridians or FIU students. Please don't think of us all in his light. We're much better than that :)
dont worry i dont!
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3650. Makoto1
If we need to have a hurricane to track can we have one more like this?



We don't have to have category 5's hitting anything that way but we still can track something.
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Quoting FloridaTigers:


Ignore him. He says statements like that to get reactions. Just ignore him.
Yeah you may be right i tried to like him but these stupid statements like that really makes it hard to like him this is my first year posting and wanted to give him a chance but its becoming clearer that chance is being wasted.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3646. szqrn1
okay hi! I have not been on this blog since last hurricane season and have moved out west. this question i have i am sure has been discussed in detail with y'all here... so forgive me for asking ...but what in the world is gonna happen when all this oil gets stirred up and sucked into a potential storm in the gulf this year? Gosh... the thought is scary to me.... my home was previously Gulfport, MS and my adult kids are still there. Any thoughts?
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3645. xcool
alexhurricane1991 yeah probably show 0000%%%%
Member Since: Posts: Comments:
Ladies and Gents, I would like to say that Janiel F. Vargas does not speak for us Southern Floridians or FIU students. Please don't think of us all in his light. We're much better than that :)
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Quoting xcool:
I can't. wait to seeing ecmwf models...
Me too probably show nothing developing.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Quoting extreme236:


If your feelings are being hurt by a weather blog then I hate to see what your like in real life. I can already imagine...

yeah... lol
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Quoting alexhurricane1991:
Why do you want hurricanes cranking you should be saying the oppisite if you dont want property loss and human lives lost.


Ignore him. He says statements like that to get reactions. Just ignore him.
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3640. xcool
I can't. wait to seeing ecmwf models...
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Quoting FIU2010:
really? xcool? whne? shear needs to relax, now in order to get the canes cranking
Why do you want hurricanes cranking you should be saying the oppisite if you dont want property loss and human lives lost.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3638. xcool
FIU2010 YEAH .
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3637. xcool
EricSFL THANKS btwntx08 :)
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Quoting FIU2010:


yes you did.
YOU NEED TO LIGHTEN UP!
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Anyways back to the realm of sanity a very serious situation is unfolding in central america hevy rain can be here for days leading to more flooding and unfortunately more deaths i hope thats not the case but they are in my prayers.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Quoting charley11:
When using Dr. Masters' blog, please refrain from posting material not relevant to the discussion of tropical weather, or the topic of the blog entry itself. Please do not engage in personal attacks or bickering. Material not conforming to these standards should be flagged with the button and ignored.

I really don't get what's so hard about this.

maybe it should be tattooed on someones hands to when they type they can read it.
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Quoting FIU2010:


yes you did.


If your feelings are being hurt by a weather blog then I hate to see what your like in real life. I can already imagine...
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3630. EricSFL
You always have a very nice attitude xcool. Good to have you around in the blog.
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Quoting alexhurricane1991:
Thats probably it

lol.
Member Since: Posts: Comments:
When using Dr. Masters' blog, please refrain from posting material not relevant to the discussion of tropical weather, or the topic of the blog entry itself. Please do not engage in personal attacks or bickering. Material not conforming to these standards should be flagged with the button and ignored.

I really don't get what's so hard about this.
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Quoting AussieStorm:

im my opinion I didn't unless he doesn't like someone telling to his face he has been ignored.
Thats probably it
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3624. xcool
LMAOOOO
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Quoting FIU2010:
:)
Yes you are happy
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Ok well time for bed

A serious situation is unfolding in Central America with all this flooding. I hope that is what is focused on the rest of the night and not some kid who wants attention

Member Since: March 10, 2010 Posts: 1 Comments: 7874
Well, the Southern Oscillation Index has switched back to positive, so technically we should be in a more La-Ninaish pattern right now:



The current reason why we are seeing so much shear over the Gulf is because of a jet split:

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Quoting alexhurricane1991:
I dont know how i was just telling him better alternatives in case someone does hurt his feelings i was not saying you did in my opinion you didnt.

im my opinion I didn't unless he doesn't like someone telling to his face he has been ignored.
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Quoting AussieStorm:
Quoting FIU2010:
alex, he deserved it after hurting my feelings, my apologies, sir.


excuse me, how did i hurt your feelings?????
I dont know how i was just telling him better alternatives in case someone does hurt his feelings i was not saying you did in my opinion you didnt.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3617. xcool
btwntx08 HAHA ..
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Quoting extreme236:


Well lemme go check my crystal ball and I will get back with you on that one.


general answers have said a few more weeks before the shear relaxes, minus one or two momentary decreases

it has been said so many times here, yet he asks anyway
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting FIU2010:


i know, but that's absolutely extraordinary, when will it let down, since we're in neutral conditions now.


Well lemme go check my crystal ball and I will get back with you on that one.
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I have had my fill of JFV for one night. Good night everyone!
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3612. xcool
FAVORABLE SHEAR COME SOONING
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Quoting FIU2010:
alex, he deserved it after hurting my feelings, my apologies, sir.
Quoting alexhurricane1991:
If someone hurts your feelings you dont have to lash back like you do sometimes either ignore him or just carry on your conversation with someone else alright.


excuse me, how did i hurt your feelings?????
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3610. EricSFL
Quoting xcool:
EricSFL LMAO.SHE BE SMOKE TO EAST TO WEST LMAO


lol
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Quoting FIU2010:
my fello collegues, when are we gonna see the la nina conditions set in?
They are set it just takes time patience is a virtue you will get your hurricane!
Member Since: April 8, 2010 Posts: 15 Comments: 2572
3607. xcool
:0
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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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