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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Aggie wayyy ahead of schedule.

000
WTPZ61 KNHC 292234
TCUEP1
TROPICAL STORM AGATHA TROPICAL CYCLONE UPDATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012010
340 PM PDT SAT MAY 29 2010

...CENTER OF AGATHA CROSSING THE COAST NEAR THE GUATEMALA/MEXICO
BORDER...

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2756. Patrap
Agatha Floater - RGB Color Infrared Loop

Check the MSLP box
Member Since: July 3, 2005 Posts: 414 Comments: 125418
Quoting cg2916:


Looks like this thing won't get into the Caribbean.


With deep layer ridging pushing into the Caribbean, not much can go east. North it is.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
That was all during the heart of the season, shear was minimal in the GOM at that time. At this time of the year there is the subtropical jet-stream in place, nothing tropical can form in the GOM now.


Well yes in most of the GOM but the southern regions bordering the Caribbean Sea, are not usually affected by early season shear. I consider this to be the only alleyway where Agatha would have a chance of redevelopment. I haven't had a chance to check shear values yet but if it is under 25kts I say there is a 20% chance. My favorite model, the GEM corresponds with my suspicions. The latest run at 12z shows Agatha's remnant moisture entering this alleyway as soon as 48 hours and begins to redevelop it by 72 hours. By 96 it is once again a weak tropical system of 1007mb near Sanibel Island, Florida. Eventually it becomes a borderline Category One hurricane by 120 with a pressure of 996mb and falling near South Carolina. With an eventual landfall near Washington D.C. as a 992mb storm.

84


120
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BP's top kill plan has failed. Will the oil ever stop flowing lol
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2752. Patrap
Looking at the Outflow in the lower BOC..shear is not the factor, and shear like gas, comes and goes.




Member Since: July 3, 2005 Posts: 414 Comments: 125418
2750. cg2916
Quoting KEEPEROFTHEGATE:


north it goes


Looks like this thing won't get into the Caribbean.
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Quoting Patrap:
akrherz May 06, 2007 Time Lapse of gravity wave action from the Tama, Iowa KCCI-TV webcam on 6 May 2007.



WOW! That's called an undular bore. Here's the Wikipedia article I wrote: Link
Member Since: August 30, 2008 Posts: 8 Comments: 2834
2748. Patrap
2145 UTC

Member Since: July 3, 2005 Posts: 414 Comments: 125418
2747. Skyepony (Mod)
I did miss a day or two of looking at it. At 1st it appeared it was off to the NW to die, then a front or something came through appeared to shove it toward the wave train. The front went on to cause some damage in Bengal area. I'm not 100% sure if what got shoved into the wave train was the one more toward the center or the one stepping off Africa now.
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Quoting Levi32:


Remnant mid-level vorticity still could have remained from Bandu's circulation and aided in the formation of this particular wave.


That is possible, yet its not been known to occur.
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2745. Levi32
Quoting Weather456:


Tropical waves form in much different way. The remnants would of dissipated over the East African highlands but remember tropical waves don't form at the surface so it is unlikely to be related to any remnant low pressure area from the Indian ocean.


Remnant mid-level vorticity still could have remained from Bandu's circulation and aided in the formation of this particular wave.
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Quoting Weather456:


to face 40 knots of shear in the GOM.


yea true lol
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting MiamiHurricanes09:
Yes but it still has to go over very mountainous central America.


the mountains extend up to the mid-levels. The low level circulation will likely tear apart leaving mid-level energy. The consensus of the global models is that this mid-level remnant will enter the GOM.
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2742. KEEPEROFTHEGATE (Mod)


north it goes
Member Since: July 15, 2006 Posts: 163 Comments: 52096
2741. Patrap
Lah,lah,..lah..

guidance/eastpac/track_early
Member Since: July 3, 2005 Posts: 414 Comments: 125418
2740. Levi32
Quoting Tropicsweatherpr:


Levi,I asked earlier this afternoon the question to our friend Skyepony who said that it may be what was left of TC Bandu.


That's a good point. Although tropical waves don't form at the surface, its vorticity very well may be being enhanced by Bandu's old circulation. The timing and satellite images of the last 7 days supports that possibility.
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Quoting Hurricanes101:


If the remnants of Agatha are moving fast enough based on the direction of movement, she may not be over those high mountains as long


to face 40 knots of shear in the GOM.
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Quoting Weather456:


The Yucatan is flat which gives it more reason to survive. But what I think the models are showing the remnants of the system entering the GOM, which is the likely scenario.
Yes but it still has to go over very mountainous central America.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2737. KEEPEROFTHEGATE (Mod)
Quoting Patrap:
Lightening Hit the Building when Doug Suttles from BP was talking,,in Robert,Louisiana.

Theres is some bad mojo and Karma afoot..here.

I betta check my Earl's list..
so its been done
Member Since: July 15, 2006 Posts: 163 Comments: 52096
2736. Patrap
La..la..la...


Member Since: July 3, 2005 Posts: 414 Comments: 125418
Quoting cg2916:
How come the ADT has been saying 995-987 MB for the past 6 hours, but the NHC has never said Agatha has gotten below 1003? If the ADT is true, this thing could make it to the Carib. If the NHC is right, this will die in the Gulf.


Agatha is at 1000mbs as of the 5pm advisory
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting atmoaggie:

Yeah, I was absent that day.

Really, those are pretty rare. Our usual t-storm outflows do not generate roll clouds, normally.

well. not around here, no. I meant in general. Ive seen them in many a storm chase video as well as personally on the northern gulf coast when we have a day of isolated but towering sea breeze storms. I also saw several when Gustav was offshore and his outer bands were enhancing sea breeze storms for a day or so.
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2733. Skyepony (Mod)
AGATHA


I looked back in my blog..I'd called for a Mexico/Guatemala landfall well over 48hrs ago. Pretty close.
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Quoting Tropicsweatherpr:


Levi,I asked earlier this afternoon the question to our friend Skyepony who said that it may be what was left of TC Bandu.


Tropical waves form in much different way. The remnants would of dissipated over the East African highlands but remember tropical waves don't form at the surface so it is unlikely to be related to any remnant low pressure area from the Indian ocean.
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2731. cg2916
How come the ADT has been saying 995-987 MB for the past 6 hours, but the NHC has never said Agatha has gotten below 1003? If the ADT is true, this thing could make it to the Carib. If the NHC is right, this will die in the Gulf.
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2730. Patrap
Quoting GeoffreyWPB:
Why does all this sound familiar?



I saw that in real time the other night on the TV,,and I almost cried,but the laughing kept me from it.
Member Since: July 3, 2005 Posts: 414 Comments: 125418
Quoting Weather456:


The Yucatan is flat which gives it more reason to survive. But what I think the models are showing the remnants of the system entering the GOM, which is the likely scenario.


If the remnants of Agatha are moving fast enough based on the direction of movement, she may not be over those high mountains as long
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting atmoaggie:

No cloud, just a sudden gust. Can and do aid in uplift of existing cells they collide with sometimes. Or the clash of 2 creates enough lift to generate a cell, like most any surface convergence does.

Or, they can be cool and dry enough to stop an existing cell...surface air doesn't want to lift when cool enough and warmer air above...inversion. Same as when a cell doesn't move and it's own cold pool outruns it's inflow...cutting off the warm, moist air.

Ontario? I dunno why not.


We occasionally have lake breezes coming off of Lake Ontario. If we could get simultaneous lake breezes from Ontario, Erie, Huron, and Georgian Bay during an outbreak of severe thunderstorms coupled with a cold front and squall lines or derechos...a big mess! I've seen a lot of those storms on radar produce severe hail or tornado/mesocyclone signatures.
Member Since: August 30, 2008 Posts: 8 Comments: 2834
2727. Patrap
Lightening Hit the Building when Doug Suttles from BP was talking,,in Robert,Louisiana.

Theres is some bad mojo and Karma afoot..here.

I betta check my Earl's list..
Member Since: July 3, 2005 Posts: 414 Comments: 125418
Quoting SouthALWX:

I think you missed roll clouds ...

Yeah, I was absent that day.

Really, those are pretty rare. Our usual t-storm outflows do not generate roll clouds, normally.
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Quoting Patrap:
There you have it! When outflow bands clash usually severe thunderstorms develop, you just got yourself a classic example there.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting MiamiHurricanes09:
There is no way that Agatha can survive going over the Yucatan, those models are definetly overdoing how long Agatha will survive.


The Yucatan is flat which gives it more reason to survive. But what I think the models are showing the remnants of the system entering the GOM, which is the likely scenario.
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Quoting Levi32:
For the sake of seeking out other interesting things, a large tropical wave appears to be in its formative stages over southern and central Sudan, in eastern Africa. The wave is lying along 28E, between 4N and 15N, and looks rather impressive compared to most waves right after birth over this area of Africa. There is an impressive mid-level wind shift associated with the wave, and it is just now entering the entrance region of the African Easterly Jet. There is also a strong PV (Potential Vorticity) maximum along the wave axis. Assuming the wave remains intact, it will take 6-10 days for it to reach the west African coast.







Levi,I asked earlier this afternoon the question to our friend Skyepony who said that it may be what was left of TC Bandu.
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Quoting SouthALWX:

Drak has the link. you should ask him. Ive read about it but I dont have the links.


I'll have too... because my whole fundamental understanding of crossover storms is now up in the air.
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2720. Patrap
Member Since: July 3, 2005 Posts: 414 Comments: 125418
beautiful, patrap!
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2718. Patrap
Anyone seen the new runs?


Snicker,boo, Hiss..
Member Since: July 3, 2005 Posts: 414 Comments: 125418
2717. Patrap
On a loop..one High Grand Oil Geo Poohbah said between the open fissure,if it exist, and the Well,,it could leak for 24 years..that reservoir.

No foolin.


But hey,..Hurricane Season Starts Tuesday.

Relax,..Oil is well..

I mean all is Well.

Member Since: July 3, 2005 Posts: 414 Comments: 125418
Quoting Levi32:
For the sake of seeking out other interesting things, a large tropical wave appears to be in its formative stages over southern and central Sudan, in eastern Africa. The wave is lying along 28E, between 4N and 15N, and looks rather impressive compared to most waves right after birth over this area of Africa. There is an impressive mid-level wind shift associated with the wave, and it is just now entering the entrance region of the African Easterly Jet. There is also a strong PV (Potential Vorticity) maximum along the wave axis. Assuming the wave remains intact, it will take 6-10 days for it to reach the west African coast.







GFS has on and off said this would be a named storm in the Central Atlantic, I believe if we were to ever get a system out there this early, it would be this season

I still think it is unlikely though
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting MrstormX:


No, I don't think so... that seems to happen for some reason with CPAC-WPAC crossovers.. but with Epac-Atl or Atl-Epac never has a storm retained its name per this Link

Drak has the link. you should ask him. Ive read about it but I dont have the links.
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everyone is talking about her not surviving, but look at the maps, she is moving faster and going over some pretty high mountains

but if she can get through those mountains, it is flat over northern Guatemala and most of Belize
Member Since: March 10, 2010 Posts: 1 Comments: 7233
2713. Levi32
For the sake of seeking out other interesting things, a large tropical wave appears to be in its formative stages over southern and central Sudan, in eastern Africa. The wave is lying along 28E, between 4N and 15N, and looks rather impressive compared to most waves right after birth over this area of Africa. There is an impressive mid-level wind shift associated with the wave, and it is just now entering the entrance region of the African Easterly Jet. There is also a strong PV (Potential Vorticity) maximum along the wave axis. Assuming the wave remains intact, it will take 6-10 days for it to reach the west African coast.







^^These last two images suddenly aren't available. I'll post them once they are.
Member Since: Posts: Comments:
Quoting atmoaggie:

No cloud, just a sudden gust. Can and do aid in uplift of existing cells they collide with sometimes. Or the clash of 2 creates enough lift to generate a cell, like most any surface convergence does.

Or, they can be cool and dry enough to stop an existing cell...surface air doesn't want to lift when cool enough and warmer air above...inversion. Same as when a cell doesn't move and it's own cold pool outruns it's inflow...cutting off the warm, moist air.

Ontario? I dunno why not.

I think you missed roll clouds ...
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Quoting MrstormX:


It is highly unlikely but it has happened before... take the 1949 Texas hurricane, Hurricane Six of 1923 or Cosme-Allison of 1989... occasionally this stuff happens. All though most of the time the tropical mountains along the Guatemala/Mexico border shred systems apart.
That was all during the heart of the season, shear was minimal in the GOM at that time. At this time of the year there is the subtropical jet-stream in place, nothing tropical can form in the GOM now.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting SouthALWX:

names are retained if a storm stays together. It would be Agatha. If a piece of energy survives and that forms a TC, then it would be Alex. If it maintains identity it keeps its name.


No, I don't think so... that seems to happen for some reason with CPAC-WPAC crossovers.. but with Epac-Atl or Atl-Epac never has a storm retained its name per this Link
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2709. xcool
happen in 1979 storms come from epac.in to gom..
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Why does all this sound familiar?

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2707. Patrap
akrherz May 06, 2007 Time Lapse of gravity wave action from the Tama, Iowa KCCI-TV webcam on 6 May 2007.

Member Since: July 3, 2005 Posts: 414 Comments: 125418

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.