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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Quoting pottery:

They hauled the one from the BOP up to the surface. For cleaning maybe. The other cams are not recording either. Dont know why.


I hope something really bad didn't happen...something they don't want anyone to see yet.
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1256. DDR
Quoting pottery:

Must be Climate Change. heheheheh
But seriously, that's not good to be so short of rainfall.
Strange stuff...
Quoting pottery:

Here too. Showers on and off all day. Nothing heavy.
Place is wet....

Pretty heavy shower taking place here.
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1255. xcool
5am depression
Member Since: September 26, 2009 Posts: 2 Comments: 15672
1253. JamesSA
Quoting pottery:

They hauled the one from the BOP up to the surface. For cleaning maybe. The other cams are not recording either. Dont know why.
On CNN they are showing the other leak now at the end of the riser pipe. It looks to me like the flow is less. (?)

It looks like they had a snowstorm down there. :-)
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Quoting Hurricanes101:
I do think this will be a TD shortly though, and the flare-ups over the last hour do make it look better
Should be a depression in the morning.
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Quoting stormwatcherCI:
If you do not live in Cayman why would you think it was a shot at you ? She was simply replying to my post that none of the rain has fallen here yet.

Thanks Sweetie. Yes, I want rain for Caymans. Just really fear you all are going to get too much! goodnight, really, this time.
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Quoting cg2916:
Just now found this:

NOAA Predicts Below Normal Eastern Pacific Hurricane Season
May 27, 2010

NOAA’s National Weather Service Climate Prediction Center today announced that projected climate conditions point to a below normal hurricane season in the Eastern Pacific this year. The outlook calls for a 75 percent probability of a below normal season, a 20 percent probability of a near normal season and a five percent probability of an above normal season.

Allowing for forecast uncertainties, seasonal hurricane forecasters estimate a 70 percent chance of 9 to 15 named storms, which includes 4 to 8 hurricanes, of which 1 to 3 are expected to become major hurricanes (category 3, 4 or 5 on the Saffir-Simpson scale).

An average Eastern Pacific hurricane season produces 15 to 16 named storms, with nine becoming hurricanes and four to five becoming major hurricanes. The Eastern Pacific hurricane season runs from May 15 through Nov. 30, with peak activity from July through September.

The main climate factors influencing this year’s Eastern Pacific outlook are the atmospheric conditions that have decreased hurricane activity over the Eastern Pacific Ocean since 1995 (opposite of the Atlantic) – and the fact that El Niño has faded.

So El Nino actually helps the EPAC. Didn't know that.


But wait, there is still a very warm area in the EPac right now, and storms can tap into that. Plus some of the heat previously over the Nino 1.2 region will be moving into the EPac. In the Western Pacific, I expect an active season due to the former El Nino Modoki warm pool drifting into the Saipan region, South China Sea to Honshu and the Kushiro current.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Chicklit:

Sorry, sloppy tired. I'm not taking shots at anyone, honestly. Just saying the Caymans will get theirs for sure. The hurricane forecasts for this season are frightening.


Ah ok, kinda tired here too, just kind of came off that way to me lol

No biggie

and yea the forecasts are crazy for this season
Member Since: March 10, 2010 Posts: 1 Comments: 7715
1248. Drakoen
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1247. xcool
i have a bad feeling about 90e
Member Since: September 26, 2009 Posts: 2 Comments: 15672
1246. Patrap


Jefferson Parish Councilman questions sudden appearance of cleanup workers

Councilman Chris Roberts says he wonders why so many cleanup workers suddenly showed up on Grand Isle's beaches Friday, just as the president was set to visit.
Member Since: July 3, 2005 Posts: 424 Comments: 128307
for the person who asked what the Atlantic Tripole is:

"The sea-surface temperature (SST) tripole, with warm anomalies off the east coast of the United States and cold anomalies north of 40°N and south of 25°N, is the leading mode of interannual variability in wintertime North Atlantic SST. Its influence on northwest African rainfall is investigated by using a large-ensemble of GCM simulations. Firstly the modeled basin-scale rainfall impact is displayed, and the results suggest: in early-mid winter (November–January), a positive SST tripole causes a reduced rainfall extending from the tropical North Atlantic northeastward to Mediterranean while a negative SST causes a south-north increased rainfall across the central Atlantic from the subtropics to the midlatitude. In late winter (February–April) a positive SST tripole causes a reduced rainfall in the central Atlantic from the subtropics to the midlatitude while a negative SST tripole induces a zonal increased rainfall from the subtropics to Mediterranean. The asymmetry and seasonal dependence of the SST influence on the basin-scale rainfall is consistent with the nonlinear response of the large-scale atmospheric circulation. Under the large-scale impact background, northwest Africa regional rainfall response is also nonlinear and seasonally dependent. In early-mid winter a positive SST tripole causes reduced rainfall, while a negative SST has little effect. In late winter a negative SST tripole induces increased rainfall, while a positive tripole has little effect. A similarly large-scale asymmetric association between SST and rainfall-circulation exists in observations in late winter, while the observed seasonal dependence of this association is relatively weak. Also, a similar SST tripole association with the regional rainfall over the northwest coast of Africa exists in observations. "
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Does anyone know if the eruption of the Pacaya volcano in Guatemala will cause global cooling? I actually hadn't heard of the eruption until just now, when I visited the blog, so I'm unsure of the details.
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Quoting Hurricanes101:


???

Not sure if the last sentence was a shot at me or not. I also don't live in the Caymans either lol
If you do not live in Cayman why would you think it was a shot at you ? She was simply replying to my post that none of the rain has fallen here yet.
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Quoting Hurricanes101:


???

Not sure if the last sentence was a shot at me or not. I also don't live in the Caymans either lol

Sorry, sloppy tired. I'm not taking shots at anyone, honestly. Just saying the Caymans will get theirs for sure. The hurricane forecasts for this season are frightening.
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I do think this will be a TD shortly though, and the flare-ups over the last hour do make it look better
Member Since: March 10, 2010 Posts: 1 Comments: 7715
1240. pottery
Quoting 850Realtor:
Anyone have the latest update on the oil spill cam?

They hauled the one from the BOP up to the surface. For cleaning maybe. The other cams are not recording either. Dont know why.
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Quoting Hurricanes101:


???

Not sure if the last sentence was a shot at me or not
Are you in Cayman ?
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1238. Patrap
Member Since: July 3, 2005 Posts: 424 Comments: 128307
Quoting AstroHurricane001:


A tripole is a pattern seen in SST temperature anomalies by latitude: right now it is warm-cold-warm.
Yup, it was exactly the opposite in 2009, cold, hot, cold. That isn't a good sign.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Anyone have the latest update on the oil spill cam?
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Quoting Chicklit:
It's the most impressive system I've seen yet this season. So it's the first. That's gotta count for something.
I was never impressed with 90L. This one's got potential. Unfortunately, it's going to bring a lot of rain quickly to areas that cannot handle it. Hopefully, some will make it over to the Caymans. If not, Mother Nature has more in store for you, I'm sure.


???

Not sure if the last sentence was a shot at me or not. I also don't live in the Caymans either lol
Member Since: March 10, 2010 Posts: 1 Comments: 7715
90E really firing intense convection over the center of circulation.

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1233. Patrap
Member Since: July 3, 2005 Posts: 424 Comments: 128307
1232. pottery
Quoting Bordonaro:


Thanks for shipping the Horse Latitudes High to North Central TX :o)!!

We're abnormally dry, and if no rain falls in about 2 weeks we will be entering another drought!

The DFW, TX AP usually receives 5.75" of rain in May, our wettest month. So far we're 3" short of normal.

This May 0.86" has fallen. At my house in SE Arlington, we were lucky, we're right at normal, thanks to our 3" rain in 1 hr.

Must be Climate Change. heheheheh
But seriously, that's not good to be so short of rainfall.
Strange stuff...
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1231. KEEPEROFTHEGATE (Mod)
Quoting WinterAnalystwx13:


So..What your basically saying is that I cant state my opinion, right? Look, I cant help that there is a crisis in the Gulf, and I understand that we dont need any more problems there, but do you really think i control the weather? I mean, I can snap my fingers, but I doubt that will do anything...
you can do and say whatever you like iam only stating its not a sure thing therefore not really needed at this time imo
Member Since: July 15, 2006 Posts: 171 Comments: 53841
Quoting HurricaneObserver:


What is a tri-pole?


A tripole is a pattern seen in SST temperature anomalies by latitude: right now it is warm-cold-warm.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting MiamiHurricanes09:
Shear is way too high in the area to support development.


Yup.
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Quoting Hurricanes101:


Im honestly not all that impressed with 90E
It's the most impressive system I've seen yet this season. So it's the first. That's gotta count for something.
I was never impressed with 90L. This one's got potential. Unfortunately, it's going to bring a lot of rain quickly to areas that cannot handle it. Hopefully, some will make it over to the Caymans. If not, Mother Nature has more in store for you, I'm sure.
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1227. hydrus
Quoting AstroHurricane001:


Comparison to Pinatubo...bad. The Pacaya volcano is actually erupting into Guatemala City.
Arenal was also erupting is Costa Rica last I heard.
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1226. pottery
Quoting DDR:

Hello pottery
Looks like another wet night again,Rains are begind here.

Here too. Showers on and off all day. Nothing heavy.
Place is wet....
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Quoting pottery:

Sorry, I had not seen your graph.
But my comment was in response to 001's post, not to you LOL
Oh, LOL.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting hydrus:
In 1991 Mount Pinatubo erupted while A typhoon was moving into the area...Big mess.


Comparison to Pinatubo...bad. The Pacaya volcano is actually erupting into Guatemala City.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting pottery:
All is as it should be, here.
But we got up to 10" in parts of the Island on Wed night, which caused some pretty severe flooding...


Thanks for shipping the Horse Latitudes High to North Central TX :o)!!

We're abnormally dry, and if no rain falls in about 2 weeks we will be entering another drought!

The DFW, TX AP usually receives 5.75" of rain in May, our wettest month. So far we're 3" short of normal for the year.

This May 0.86" has fallen. At my house in SE Arlington, we were lucky, we're right at normal, thanks to our 3" rain in 1 hr.
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1222. pottery
Quoting MiamiHurricanes09:
The graph I posted is based on direct landfalls. I doubt we will get a tropical cyclone making a direct landfall in Guyana or New York.

Sorry, I had not seen your graph.
But my comment was in response to 001's post, not to you LOL
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Quoting Chicklit:
oops misspelled.
calling it a day.
night all.
Good night.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting Hurricanes101:
I guess I am in the minority but 90E is not all that impressive to me in terms of organization

However those rains could really cause some problems in El Salvador


I think the convection is very organized, it just lacks a well-defined surface circulation.
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Quoting MiamiHurricanes09:
I haven't hear that word in a while. Incroyable!
oops misspelled.
calling it a day.
night all.
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Quoting MiamiHurricanes09:


Im honestly not all that impressed with 90E
Member Since: March 10, 2010 Posts: 1 Comments: 7715
1215. DDR
Quoting pottery:
All is as it should be, here.
But we got up to 10" in parts of the Island on Wed night, which caused some pretty severe flooding...

Hello pottery
Looks like another wet night again,Rains are begind here.
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1214. Patrap
90E Floater - RGB Color Infrared Loop
Member Since: July 3, 2005 Posts: 424 Comments: 128307
Quoting dsenecal2009:
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...


That's weird. You have what look like thin lines of energy moving southwest and a bow echo moving north.
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Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting Chicklit:
Encroyable!
I haven't hear that word in a while. Incroyable!
Member Since: September 2, 2009 Posts: 130 Comments: 21193
1210. xcool
WEATHER456..mail
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting cajunkid:
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.


Not if it gets caught in the wetlands and bayous. Lightning might burn off the oil there, but damage to coastal marshes and plants would be a real problem.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
1208. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15672
1207. pottery
Quoting Bordonaro:

So, I gather the Calabash Tree was correct!

Welcome to Rainy Season 2010 in Trinidad and Tobago :o)!!
All is as it should be, here.
But we got up to 10" in parts of the Island on Wed night, which caused some pretty severe flooding...
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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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