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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Any previous discussion and/or thoughts what the oil in the GOM will do to the SST?
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3806. IKE
I had 1.10 inches of rain yesterday at my house, bringing my monthly total to 6.51.
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Looks like alot of rain here in pan handle today n tommorow 70% chance
Member Since: September 8, 2005 Posts: 0 Comments: 1385
3804. IKE
Quoting stormhank:
morning ike i see theres still alotta shear over GOM thru bahamas....like 60mph plus...probabaly take that awhile to lessen,may not have a early start,im guessing later June til things pop


Agree...too much shear.
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erm... post.

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Need 198 more comments in 3hours to get to 4000posts in 48hours. We can do it!
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I was answering the question at hand. Thank you
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morning ike i see theres still alotta shear over GOM thru bahamas....like 60mph plus...probabaly take that awhile to lessen,may not have a early start,im guessing later June til things pop
Member Since: September 8, 2005 Posts: 0 Comments: 1385
3793 msgambler "szqrn1, The oil will not get "sucked" up into the storm. As your thinking, that is evaporation and oil does not do that. Not in the way your thinking anyway."

About 30%to40% of sweet light crude is composed of volatiles that evaporate quite readily&rapidly...if it's allowed to stay on the surface rather than mixed into the water column by dispersants.
And if a hurricane can pick up lawn furniture, it can pick up thin-film oil from the sea surface and loft it inland as spray.

Obviously there ain't gonna be an oilycane for real: WAY WAY WAY too high water-to-oil ratio for that. But I suspect folks are gonna smell&taste crude in the same manner that they smell&taste salt&seaweed.
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3798. IKE
If you believe....

(1)The ECMWF...quiet in the Atlantic through June 9th.

(2)The GFS...quiet in the Atlantic through June 15th.
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3797. Greyelf
Wow. 76 pages with the first named storm. It's going to be a long season.
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Quoting WatchingThisOne:


Read the last few blog entries by Dr. Masters. They are quite informative. NHC also has a 2 page "brochure" out on this ... perhaps someone could post the link? I failed to save it.

NHC "brochure"
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3752 AussieStorm "you can call me 'Al'."

Great. Just what this blog needs, another one of them thar GlobalWarmers.
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anyone on? morning all
Member Since: September 8, 2005 Posts: 0 Comments: 1385
szqrn1, The oil will not get "sucked" up into the storm. As your thinking, that is evaporation and oil does not do that. Not in the way your thinking anyway. It may, however, come further inland due to storm surge. And while I'm at it Good Morning everyone!!
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3653 melwerle "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..."

No problemo, it ain't like SD has mosquitoes. And ya barely even need a house 'ceptin' to keep out mosquitoes.

Just be grateful that ya don't hafta face the huge and powerful acne that's gonna make landfall in Miami this year. AND they've got mosquitoes. Things're gonna get really ugly really quick.
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Quoting 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?


Read the last few blog entries by Dr. Masters. They are quite informative. NHC also has a 2 page "brochure" out on this ... perhaps someone could post the link? I failed to save it.
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"A little sun and air and water, and all the flowers of spring are blooming."
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Usually just hear alotta crickets chirping for the next couple of hours or so.
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anyone on???
Member Since: September 8, 2005 Posts: 0 Comments: 1385
Oh c'mon guys, don't quit now. We only got a little more than 5hours left to make another 214 comments to get to 4000posts in 48hours.
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3785. HadesGodWyvern (Mod)
Post Time: 8:40 AM GMT on May 30, 2010
high shear in aTL TP"

Sorry, I am unfamiliar with the abbreviations?acronyms aTL TP.
Atlantic Tropopause? a TropicalLow TroughPressure? a TrulyLousy TemperatureProfile?
Yep, I don't know enough to even make a halfway respectable guess.


hmm

ATL TP = Atlantic Tropical Potential?

There is so many abbrievations that other people use now a days, LOL
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3784. HadesGodWyvern (Mod)
National Hurricane Center
Tropical Cyclone Advisory #5
TROPICAL DEPRESSION, FORMER AGATHA (EP012010)
9:00 AM UTC May 30 2010
==============================================

SUBJECT: "AGATHA" dissipates over the mountains of western Guatemala

At 9:00 AM UTC, Tropical Depression, Former Agatha (1007 hPa) located at 15.6N 91.7W or 60 NM northeast of Tapachula, Mexico has sustained winds of 25 knots with gusts of 30 knots. The cyclone is reported as moving north northeast at 5 knots.

THIS IS THE FINAL ADVISORY FROM THE NATIONAL HURRICANE CENTER OF THIS SYSTEM..
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3582 xcool "WT[[[[[ WT[[[[ THAT KIND CRAZYYYY"

3654 aspectre "...the Caribbean...what am I not seeing that makes a hurricane not there?"

3660 xcool "...high shear in aTL TP "

Sorry, I am unfamiliar with the abbreviations?acronyms aTL TP.
Atlantic Tropopause? a TropicalLow TroughPressure? a TrulyLousy TemperatureProfile?
Yep, I don't know enough to even make a halfway respectable guess.
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Hello,

What about 20N 80W?

is it posible to developed?
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3781. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Outlook
11:30 AM IST May 30 2010
=====================================

A low pressure area would form over southeast and adjoining east central Arabian Sea during the next 48 hours

Convective clouds are seen over parts of south and adjoining central Arabian Sea, east central Bay of Bengal, and Andaman Sea.

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3780. xcool
i'm out to bye alex
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Well it was an eventful first hours os sunday to say the least but its time for me to sign off i will see you all tomorrow and have the people in central america in your prayers as they are dealing with heavy rainfall from what soon will be Ex-agatha but that doesnt mitigate the impact what so ever so with that i bud you farewell till tomorrow!
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3778. xcool
bye rob
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3775. xcool
big time..she doom buzzz
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Quoting xcool:


Dang looks like agatha got run over by a mack truck looks horrible
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3772. xcool
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3771. xcool


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Quoting FIU2010:
Welcome to the WU Community. We're looking forward to chatting with you. Where may I find it to read it, young lad?


Thanks. You can find my forecast as my first blog.

Quoting alexhurricane1991:
Welcome to the blogs!


Thanks!
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3767. xcool


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Quoting btwntx08:

well i know ur alex already we sometimes meet in the weather chat room here
Yeah i know havent been in the chat room at all lately.
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3764. xcool



check this outtt
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Quoting StarnzMet:
Hey guys new to the place. I'm currently an undergrad student and I want to get my masters in broadcast meteorology. Check out my 2010 Hurricane Forecast. I think this upcoming hurricane season will keep me coming back here often.
Welcome to the blogs!
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Quoting btwntx08:
and u can call me rob :)
Well hello there rob!
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3760. xcool
btwntx08 haha lmao
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3757. xcool



54hr





162..
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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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