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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1107. cg2916
Quoting nrtiwlnvragn:


No, it is not oficially a TD, but they did forecast a track.

Getting closer, though
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1106. hydrus
Quoting pottery:
Anyone monitoring the "topkill" cam?
If so, what is going on now?
Looks kind of scary....
Now there saying it might be Sunday before they know if it is sealed.....
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1105. cg2916
Quoting Hurricanes101:


so DB is actually an upgrade from LO?


Well, if you think about it, a low can be just about anything. But to be a disturbance, you need to have some nice convection and circulation and all that stuff.
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I uploaded some pics, all are welcomed to rate them...just click on the image.









Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting cg2916:


OFCL is running... is it a TD? For a second there, I wad like, "How long has this thing been tropical?"


No, it is not oficially a TD, but they did forecast a track.
Member Since: September 23, 2005 Posts: 14 Comments: 11268
1102. Drakoen
Quoting atmoaggie:
Someone knows what's up...what's up?

(busy actually working)



Not sure but you can always use the Eastern East Pacific imagery
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Quoting MiamiHurricanes09:

where's 25% on that map lol
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Quoting Hurricanes101:


Right but before the last advisory, this has been known as a Low, now it is a Disturbance


Super Duper Megacane? Who knows. I'll post this link one more time before I call it a night. Dr. Masters had some great insight to the oil spill/hurricane relationship. He also gives us a sneak peek at his predictions for the upcoming season. Read it.

Later Stormsurgeon.

Dr. Masters comments
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1099. hydrus
Quoting AstroHurricane001:


So the heaviest rains could hit close to the erupting volcano. Yikes.
In 1991 Mount Pinatubo erupted while A typhoon was moving into the area...Big mess.
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1098. cg2916
Quoting nrtiwlnvragn:
EP 90 2010052818 3 OFCL 0 128N 945W 30 0 TD
EP 90 2010052818 3 OFCL 3 129N 944W 30 1005 TD
EP 90 2010052818 3 OFCL 12 133N 937W 35 0 TS
EP 90 2010052818 3 OFCL 24 137N 929W 40 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 48 146N 915W 35 0 TS
EP 90 2010052818 3 OFCL 72 151N 913W 20 0 TD


OFCL is running... is it a TD? For a second there, I wad like, "How long has this thing been tropical?"
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Quoting KEEPEROFTHEGATE:
one level away from tropical depression


so DB is actually an upgrade from LO?
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Quoting Stormchaser2007:
This is...uhm...scary.

Pretty defined tri-pole



Yep, all the heat is focused in the Tropics. Its only a matter of time now.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Someone knows what's up...what's up?

(busy actually working)

Member Since: August 16, 2007 Posts: 6 Comments: 12463
Strange thunder and intense lightning suddenly appearing over Houston..





We've been quite dry for a while now, and this system doesn't seem to be bringing any precipitation. Just thunder and lightning...
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Quoting nrtiwlnvragn:


No. They did not classify it, seems they were ready to and backed off.

Disclaimer from the ATCF site:
Users are also cautioned that the data in these files are subject to frequent revisions and can differ from information issued in official NHC products.


I realized a second ago that I messed up. I modified the post.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
1092. KEEPEROFTHEGATE (Mod)
Quoting Hurricanes101:
EP, 90, 2010052900, , BEST, 0, 130N, 942W, 30, 1005, DB

hmmmm wonder if this means anything
one level away from tropical depression
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Quoting Stormchaser2007:
This is...uhm...scary.

Pretty defined tri-pole



What is a tri-pole?
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Member Since: Posts: Comments:
Quoting SevereHurricane:




There you go! TD 1E is here!


No. They did not classify it, seems they were ready to and backed off.

Disclaimer from the ATCF site:
Users are also cautioned that the data in these files are subject to frequent revisions and can differ from information issued in official NHC products.
Member Since: September 23, 2005 Posts: 14 Comments: 11268
1088. pottery
Anyone monitoring the "topkill" cam?
If so, what is going on now?
Looks kind of scary....
Member Since: Posts: Comments:
a hurricane might be a good thing for the oil. Mixing and dispursing would lessen the effects.

I know, I know...you all think otherwise, but this is not the same kind of oil as in the Exxon V. spill. It will break down quickly, especially if well dispursed.
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Quoting WinterAnalystwx13:


yay!!!


It was a mistake.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
1085. leo305
so we now have our first tropical depression of the pacific..
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting SevereHurricane:




There you go! TD 1E is here!


yay!!!
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1083. Drakoen
Quoting nrtiwlnvragn:
EP 90 2010052818 3 OFCL 0 128N 945W 30 0 TD
EP 90 2010052818 3 OFCL 3 129N 944W 30 1005 TD
EP 90 2010052818 3 OFCL 12 133N 937W 35 0 TS
EP 90 2010052818 3 OFCL 24 137N 929W 40 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 48 146N 915W 35 0 TS
EP 90 2010052818 3 OFCL 72 151N 913W 20 0 TD


Just south of NE
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Quoting Ossqss:


I think your correct LoL :) Etna here!







Wow, that looks almost like an angel rising out of hellfire.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Hurricanes101:


Right but before the last advisory, this has been known as a Low, now it is a Disturbance
What does that mean?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
1079. pottery
Quoting AstroHurricane001:


So if the slick persists as the eye of a hurricane pases over, the winds would be calm but the seas would be very high. Would oil under the eyewall pool upward into the space under the eye as oil floats upward and rises as it warms? Could the oil warm the air due to solar radiation and heat in the storm, producing the effect of strengthening or ERC-ing the storm's eyewall?

This is completely outside of my experience. I have no idea, really.
In fact, everything related to hurricanes and oilslicks is pure conjecture based on some assumed parameters.
We have never been here before...
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Member Since: September 2, 2009 Posts: 130 Comments: 21194
This is...uhm...scary.

Pretty defined tri-pole

Member Since: Posts: Comments:
EP 90 2010052818 3 OFCL 0 128N 945W 30 0 TD
EP 90 2010052818 3 OFCL 3 129N 944W 30 1005 TD
EP 90 2010052818 3 OFCL 12 133N 937W 35 0 TS
EP 90 2010052818 3 OFCL 24 137N 929W 40 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 48 146N 915W 35 0 TS
EP 90 2010052818 3 OFCL 72 151N 913W 20 0 TD
Member Since: September 23, 2005 Posts: 14 Comments: 11268
Quoting StormSurgeon:


Thanks 456, now I understand that the expansion you were speaking of was regarding the expansion of the rainfall umbrella as a tropical system makes landfall. Obviously, Salina Cruz will see copius amounts of rainfall from 90E. Don't you think?


Salina Cruz is a good distance away from the storm, in fact it is located within the cirrus overspread (CO).

CDO - Central dense Overcast
OBA - outer band area
ECT - embedded cloudtops

Member Since: July 24, 2005 Posts: 407 Comments: 19076
You can get an idea of NHC thinking on track, Ships was run using OFCI (Official track interpolated).
Member Since: September 23, 2005 Posts: 14 Comments: 11268
Quoting Weather456:
General topography of the area of interest. The highest rainfall will likely occur along the windward slopes of the Chiapas mountains and Guatemalan highlands on the right side of the storm where onshore flow and orographic lift are greatest.





So the heaviest rains could hit close to the erupting volcano. Yikes.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
1072. Drakoen
Seems the ASCAT pass didn't convince the NHC of a well-defined center. At any rate the system continues to exhibit organized convection.
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Quoting pottery:

Not really. The point was made re. a very calm sea condition at the time.
Sea conditions in a storm would be different as you know.


So if the slick persists as the eye of a hurricane pases over, the winds would be calm but the seas would be very high. Would oil under the eyewall pool upward into the space under the eye as oil floats upward and rises as it warms? Could the oil warm the air due to solar radiation and heat in the storm, producing the effect of strengthening or ERC-ing the storm's eyewall?
Member Since: August 30, 2008 Posts: 8 Comments: 2835
1070. cg2916
Quoting Hurricanes101:


Right but before the last advisory, this has been known as a Low, now it is a Disturbance


Do disturbances have lows?
Member Since: Posts: Comments:
Quoting KEEPEROFTHEGATE:


Or maybe it has eaten a hole in the warmer water.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Hurricanes101:
EP, 90, 2010052900, , BEST, 0, 130N, 942W, 30, 1005, DB

hmmmm wonder if this means anything


Who are you testing?

Blop model.

Link
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Quoting nrtiwlnvragn:


DB - disturbance,
TD - tropical depression,
TS - tropical storm,
TY - typhoon,
ST - super typhoon,
TC - tropical cyclone,
HU - hurricane,
SD - subtropical depression,
SS - subtropical storm,
EX - extratropical systems,
IN - inland,
DS - dissipating,
LO - low,
WV - tropical wave,
ET - extrapolated,
XX - unknown.


If they start using XX we are in trouble.


Right but before the last advisory, this has been known as a Low, now it is a Disturbance
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Quoting Ossqss:
Off topic, but this is kinda cool. Volcanic Smoke Ring! Clickable picture :)





WOW at auroras!
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Hurricanes101:
EP, 90, 2010052900, , BEST, 0, 130N, 942W, 30, 1005, DB

hmmmm wonder if this means anything


DB - disturbance,
TD - tropical depression,
TS - tropical storm,
TY - typhoon,
ST - super typhoon,
TC - tropical cyclone,
HU - hurricane,
SD - subtropical depression,
SS - subtropical storm,
EX - extratropical systems,
IN - inland,
DS - dissipating,
LO - low,
WV - tropical wave,
ET - extrapolated,
XX - unknown.


If they start using XX we are in trouble.
Member Since: September 23, 2005 Posts: 14 Comments: 11268
Quoting hydrus:
Dennis looked like crap its entire existence. And it was a Cape Verde storm.


yea not sure why he was referencing Dennis in 1981, completely different situation
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1063. FIU2010
Quoting IKE:


Nope...watching the NBA.



ohh, what's on nbc right now?
1062. cg2916
Quoting Hurricanes101:


It is elongated from NE to SW that is how


It was like that earlier, but notice how in the middle of the elongation, it makes a quick East to West cut-through.
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1061. hydrus
Quoting kuppenskup:
Dont count out the possibility of another center reforming over the Gulf if the coc of 90E stays overland for too long. Remember Dennis 1981 over Cuba?
Dennis looked like crap its entire existence. And it was a Cape Verde storm.
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Quoting cg2916:


Look at my ASCAT pic:



How is that not well-defined?


It is elongated from NE to SW that is how
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1059. cg2916
Quoting Hurricanes101:


yup and satellite confirms, 90E is getting less organized again

This system can't seem to get its act together enough


It's DMIN, did the exact same thing last night.
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Quoting AstroHurricane001:


But in some areas the slick is metres thick, and the could be upwelling from the shallower subsurface areas. What about a very small hurricane heading over the dense slick? Would it expand, or strengthen?

But it will not be able to dampen waves created well out to sea where there isn't enough surface slick to stop them from forming. Then the mixing begins...

And the dense surface slick, covering square miles, will be staying about where it is until BP does something constructive, or at about 29 N. Very uncommon that we get very small hurricanes. (anyone know of any smaller than Camille in the northern gulf?)

Even if we got a little one, still would induce enough mixing that the surface oil would have an undetectable effect if any at all on the hurricane itself, again, in my honest opinion. Even the smallest cat 1 puts surface waters in motion. We all saw what happened when oil reached the loop current. A thin tendril stretched out over miles and miles. Moving water will do some things guaranteed to break up a solid slick.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
1057. cg2916
Quoting Hurricanes101:


LO means Low I would think
DB means Disturbance

In other words the NHCs thinking that the center is still not well-defined is correct


Look at my ASCAT pic:



How is that not well-defined? That's better than earlier.
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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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