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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906. xcool
i miss QuickSCAT .90e upgrade very soon.
imo..
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Quoting SevereHurricane:
Very nice upper level anti-cyclone is situated directly atop 90E.

Agreed!
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904. xcool
Bordonaro .hey .yeah..
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Quoting AstroHurricane001:


Which will probably protect it from at least some of the shear in the GOM currently. However the other limiting factor could be dry air. Also watch its effects on the oil spill as a clue to later this season.
and the high terrain of guatamala.
Member Since: April 8, 2010 Posts: 15 Comments: 2572
Quoting AstroHurricane001:


No, it wasn't. There's a chance for the season to be mostly neutral, but also a chance for it to temporarily be above the +0.5C range late in the season. However the season could have Nino 3.4 indications anywhere from a weak El Nino to a strong La Nina (say +1.1C to -2.3C).
So you are going against every single model, and saying that we are going to have a El NiƱo. I don't think so.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
901. Skyepony (Mod)
Rain has consolidated more offshore the last 3 hrs
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Quoting xcool:
so gfs and ngp take in gom..

Let us all wait and see what is left of 90E after its trip across Central America. Odds are there will not be much left of 90E.

IF conditions allow, it is possible 90E may become some type of tropical system in the Caribbean Sea.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting alexhurricane1991:
it was probably a typo


No, it wasn't. There's a chance for the season to be mostly neutral, but also a chance for it to temporarily be above the +0.5C range late in the season. However the season could have Nino 3.4 indications anywhere from a weak El Nino to a strong La Nina (say +1.1C to -2.3C).
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting AstroHurricane001:


Which will probably protect it from at least some of the shear in the GOM currently. However the other limiting factor could be dry air. Also watch its effects on the oil spill as a clue to later this season.


We shall see.
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897. xcool
so gfs and ngp take in gom..
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Quoting SevereHurricane:
Very nice upper level anti-cyclone is situated directly atop 90E.



Which will probably protect it from at least some of the shear in the GOM currently. However the other limiting factor could be dry air. Also watch its effects on the oil spill as a clue to later this season.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
895. xcool



new


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A little old but its all good.

28/1745 UTC 13.4N 94.7W T1.5/1.5 90E -- East Pacific
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Quoting Hurricanes101:


Not at all, just saying that this year is in no way setting up to be like last season. There is no evidence of that is all we are saying




Sorry, I was just replying to what Floodman said but I cant quote him for some reason.
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Quoting AstroHurricane001:
If I believe the CMC, I'm inclined to predict a weak cat. 1 landfall on Long Island on June 5, or maybe it'll be similar to Barry 2007. However, I do expect some Tehuantepec-GOM cross-over hurricanes this season.

On the other hand, a prediction by NOAA for an active season doesn't nessecarily mean it'll be active, even though I and almost everybody else here has been predicting an unusually active season. For example in 2006, their forecast by this time was 17-9-5, and it turned out to be 10-5-2. But then again, in 2006 an El Nino unexpectedly set in and the SAL was strong, and this year there will be at most a chance of a weak-to-moderate El Nino during the season, or it could be a dual El Nino-La Nina pattern, which would increase hurricane activity rather than hinder it.

The SST off of LI are in the 55-56F range. The warmest Gulf Stream waters off of C FL up to the Outer Banks region off of NC are only between 72-78F. It is NOT possible for any type of TC to survive those cold waters.

IF 90E survives its trip over Guatemala it will barely be an area of Low pressure. The mountains of that region range between 8-11,000 ft. That is enough to rip apart a mature hurricane, no less an area of Low pressure.

It is possible that we might have a TD in the Caribbean IF 90E can regroup. I would not count on anything at this point :o)!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting MrstormX:


A hurricane in Long Island (NY I presume) this time of year... I highly doubt it. The SSts in that region are not conductive enough for that yet. A tropical storm in Florida, more likely.


The CMC solution (crazy as always) has the potential to bring the storm up to a low-end cat. 3. However I doubt that this will be the case. We'll really need to watch the storm once it gets into the Yucatan Channel but if it follows a path like Barry it could become a hurricane under current conditions.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Stormchaser2007:


I really hope you mean Nina.
it was probably a typo
Member Since: April 8, 2010 Posts: 15 Comments: 2572
re 774 A
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Quoting AstroHurricane001:
If I believe the CMC, I'm inclined to predict a weak cat. 1 landfall on Long Island on June 5, or maybe it'll be similar to Barry 2007. However, I do expect some Tehuantepec-GOM cross-over hurricanes this season.

On the other hand, a prediction by NOAA for an active season doesn't nessecarily mean it'll be active, even though I and almost everybody else here has been predicting an unusually active season. For example in 2006, their forecast by this time was 17-9-5, and it turned out to be 10-5-2. But then again, in 2006 an El Nino unexpectedly set in and the SAL was strong, and this year there will be at most a chance of a weak-to-moderate El Nino during the season, or it could be a dual El Nino-La Nina pattern, which would increase hurricane activity rather than hinder it.


I really hope you mean Nina.
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Very nice upper level anti-cyclone is situated directly atop 90E.

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885. xcool




green mean Tropical Depression:
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If it were to come to S Fla it would prob just be a glob of rain mixed in with some severe t-storms. But that's it if it even comes to S fla.
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Quoting AstroHurricane001:
If I believe the CMC, I'm inclined to predict a weak cat. 1 landfall on Long Island on June 5, or maybe it'll be similar to Barry 2007. However, I do expect some Tehuantepec-GOM cross-over hurricanes this season.

On the other hand, a prediction by NOAA for an active season doesn't nessecarily mean it'll be active, even though I and almost everybody else here has been predicting an unusually active season. For example in 2006, their forecast by this time was 17-9-5, and it turned out to be 10-5-2. But then again, in 2006 an El Nino unexpectedly set in and the SAL was strong, and this year there will be at most a chance of a weak-to-moderate El Nino during the season, or it could be a dual El Nino-La Nina pattern, which would increase hurricane activity rather than hinder it.


A hurricane in Long Island (NY I presume) this time of year... I highly doubt it. The SSts in that region are not conductive enough for that yet. A tropical storm in Florida, more likely.
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Quoting Drakoen:
On the verge of becoming a Tropical Depression:



Yikes. Haiti is getting some heavy rains.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Weather456:


It can also split rather than just lift...but I see neither solution occurring in the near future.
I agree with you
Member Since: April 8, 2010 Posts: 15 Comments: 2572
If I believe the CMC, I'm inclined to predict a weak cat. 1 landfall on Long Island on June 5, or maybe it'll be similar to Barry 2007. However, I do expect some Tehuantepec-GOM cross-over hurricanes this season.

On the other hand, a prediction by NOAA for an active season doesn't nessecarily mean it'll be active, even though I and almost everybody else here has been predicting an unusually active season. For example in 2006, their forecast by this time was 17-9-5, and it turned out to be 10-5-2. But then again, in 2006 an El Nino unexpectedly set in and the SAL was strong and it was preceded by a record-breaking above-average year whereas this season was preceded by an average year, and this year there will be at most a chance of a weak-to-moderate El Nino during the season, or it could be a dual El Nino-La Nina pattern, which would increase hurricane activity rather than hinder it.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Weather456:


It can also split rather than just lift...but I see neither solution occurring in the near future.
Agreed.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting MiamiHurricanes09:
Yeah. You have to wait for the subtropical jet stream to lift which probably won't happen until June.


It can also split rather than just lift...but I see neither solution occurring in the near future.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Drakoen:
On the verge of becoming a Tropical Depression:


I saw some cloud formations yesterday that I mentioned that I have seen precede TC development. Seems that I was correct. Would you think it would be better to sketch the image for future reference or use a saved photo? Ive found sometimes sketches are better, was wondering which you guys preferred. ( I saw 456 post a diagram with sketches of sub tropical storms and it got me thinking if maybe sketches would be better.)
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Quoting Drakoen:
For those who may not have seen

My 2010 Atlantic Hurricane Season Forecast


I read it earlier. It was a very good read.
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Howdy:

I vote for "A"
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Quoting wunderkidcayman:
I agree with you alexhurricane1991 I will not disregard it totally but I am still going to wait for the 00Z runs before I say where I think 90-E will go
and that is fine i am too
Member Since: April 8, 2010 Posts: 15 Comments: 2572
From the 22:05 UTC Eastern Pacific discussion.

...SPECIAL FEATURE...
AN AREA OF DISTURBED WEATHER IS SOUTH OF THE GULF OF TEHUANTEPEC
WITH A BROAD 1005 MB SURFACE LOW NEAR 13N94W. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 12N TO 16N BETWEEN 91W AND 96W. THE SYSTEM
CONTINUES TO PRODUCE ABUNDANT TROPICAL MOISTURE INLAND OVER SW
MEXICO AND GUATEMALA. A 28/1616 UTC ASCAT SATELLITE PASS WENT OVER
THE LOW CENTER DEPICTING 20-25 KT WINDS WITH STRONGEST WINDS SE OF
THE CENTER. THE CONSENSUS OF NUMEROUS TROPICAL TRACK MODELS HAS THIS
LOW MOVING NE TOWARDS THE COAST OF GUATEMALA. THERE IS A HIGH CHANCE
FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE OVER THE NEXT 48
HOURS. REGARDLESS OF THE POTENTIAL FOR DEVELOPMENT...THIS SYSTEM IS
EXPECTED TO PRODUCE VERY HEAVY RAINFALL AND FLOODING OVER PORTIONS
OF CENTRAL AMERICA DURING THE NEXT FEW DAYS.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting Drakoen:
On the verge of becoming a Tropical Depression:



Agreed Drak. 90E is looking much healthier this afternoon.
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That area of Mexico near the Guatemala border is full of large tropical mountains. I fear for the many poor villages of Mayan decedents that live in these mountains because 90E could cause devastating mudslides and flooding. If 90E survives this area, the Atlantic could allow it to redevelop but probably not substantially.
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Quoting kuppenskup:
No-Im gonna be like everyone else on here and predict 22 storms just to fit in with the crowd. If I dont then I just dont fit it, is that it?


Not at all, just saying that this year is in no way setting up to be like last season. There is no evidence of that is all we are saying


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I agree with you alexhurricane1991 I will not disregard it totally but I am still going to wait for the 00Z runs before I say where I think 90-E will go
Member Since: June 13, 2009 Posts: 2 Comments: 11704
Quoting SevereHurricane:


Wind Shear is unfavorably high in the Gulf of Mexico and is expected to remain that way for quite sometime.
Yeah. You have to wait for the subtropical jet stream to lift which probably won't happen until June.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
For those who may not have seen

My 2010 Atlantic Hurricane Season Forecast
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That system is gonna have to start moving fast. If not it's gonna be torn to shreds over those mountains.
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Quoting FIU2010:
miami, should we monitor this situation?


Wind Shear is unfavorably high in the Gulf of Mexico and is expected to remain that way for quite sometime.
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I'm in the NHC directory to see if we are going to get TD 1-E at 8:00 PM EDT (5:00 PM EDT).
Member Since: September 2, 2009 Posts: 130 Comments: 21109
863. xcool
kool thank
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Been raining here in the island all day long

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Drakoen:
On the verge of becoming a Tropical Depression:

I agree.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
No-Im gonna be like everyone else on here and predict 22 storms just to fit in with the crowd. If I dont then I just dont fit it, is that it?
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Quoting xcool:
90E MOVE NNE OR NNW
NE at 2 MPH.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
On the verge of becoming a Tropical Depression:

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Quoting FIU2010:
miami, should we monitor this situation?
Well if more models jump aboard with this solution yes. But I doubt, if it does happen, that it will be intense. Way too much shear for development there.
Member Since: September 2, 2009 Posts: 130 Comments: 21109

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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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