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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2857. Levi32
Quoting FIU2010:


then normaL? but the carib. is in its rainy season, therefore, isn't taht to eb expected?


Yes, but their rainy season is expected to be wetter than normal this year.
Member Since: Posts: Comments:
Quoting AstroHurricane001:


It could be a dry pocket, but it looks like an eye making landfall near the Mexico-Guatemala border popping up to the east of a sudden burst of convection in the CDO at landfall.
Agatha has a anticyclone aloft, so it isn't a dry pocket. It's a hot tower, Patrap can further explain those, :).
Member Since: Posts: Comments:
Quoting kmanislander:


The real damage is yet to come though. Watch those thunderstorms blow up with the forcing that will take place on the upslopes. Night time will also help those high cloud tops cool down quickly thus enhancing the convection.
Exactly.
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Quoting CybrTeddy:


We've had landfall for a while now..

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...

AT 340 PM PDT...2240 UTC...SURFACE OBSERVATIONS AND SATELLITE IMAGES
INDICATE THAT THE CENTER OF AGATHA IS CROSSING THE COAST ALONG THE
BORDER OF MEXICO AND GUATEMALA...AND IS NOW LOCATED JUST SOUTHEAST
OF TAPACHULA MEXICO.



I guess my glasses were just fine then
Member Since: Posts: Comments:
Quoting gordydunnot:
456 while you are here or anyone if you please. Are high subject to the same classification as lows specifically ull,mll,llc or are they pretty much top to bottom in the troposphere.

Highs can be at any level (just as lows), do sometimes end up stacked (as do lows)...

Our coldest winter outbreaks are associated with stacked highs to our west, usually.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
2852. leo305
agatha is doing a katrina (when it hit miami) exploding at landfall
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Quoting CybrTeddy:


We've had landfall for a while now..

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...

AT 340 PM PDT...2240 UTC...SURFACE OBSERVATIONS AND SATELLITE IMAGES
INDICATE THAT THE CENTER OF AGATHA IS CROSSING THE COAST ALONG THE
BORDER OF MEXICO AND GUATEMALA...AND IS NOW LOCATED JUST SOUTHEAST
OF TAPACHULA MEXICO.

Oh! I didn't notice that they posted that, thanks.
Member Since: Posts: Comments:
Quoting Hurricanes101:
Agatha doesnt have an eye



It could be a dry pocket, but it looks like an eye making landfall near the Mexico-Guatemala border popping up to the east of a sudden burst of convection in the CDO at landfall.
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Just in from Faux news. The Obama oilzilla hurricane is threatening all the gulf. We told you he was more slippery than that Bill Clinton.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
Quoting MiamiHurricanes09:
Me too.


The real damage is yet to come though. Watch those thunderstorms blow up with the forcing that will take place on the upslopes. Night time will also help those high cloud tops cool down quickly thus enhancing the convection.
Member Since: Posts: Comments:
2846. cg2916
Quoting Patrap:


That's landfall.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Quoting MiamiHurricanes09:
The strongest of the convection is going ashore along the Mexico/Guatemala coast. I think we have landfall, if my eyes aren't mistaken.


We've had landfall for a while now..

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...

AT 340 PM PDT...2240 UTC...SURFACE OBSERVATIONS AND SATELLITE IMAGES
INDICATE THAT THE CENTER OF AGATHA IS CROSSING THE COAST ALONG THE
BORDER OF MEXICO AND GUATEMALA...AND IS NOW LOCATED JUST SOUTHEAST
OF TAPACHULA MEXICO.

Member Since: Posts: Comments:
Quoting AstroHurricane001:


The volcano in Guatemala and the one in Ecuador erupted both in the same week. Now they're saying that the giant Katla volcano is due to erupt imminently in Iceland.
I know 2012 is getting close, but... LOL.
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Quoting MrstormX:

Shows you the American Media bias, we hear all about a European Volcano... yet I had no idea there was one erupting in Central emrica until today.


The volcano in Guatemala and the one in Ecuador erupted both in the same week. Now they're saying that the giant Katla volcano is due to erupt imminently in Iceland.
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2842. Levi32
Quoting AstroHurricane001:


Plus with the Caribbean looking more like early September than early June, it has about three more months than usual to warm to maximum temperature.


But its maximum temperature won't be any higher above normal than it is now, because the pattern is reversing to cloudier and wetter than normal in the Caribbean.
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Quoting kmanislander:


I agree on that. I saw it in pretty much that position about 2 hours ago. No Sunday morning landfall for this one.
Me too.
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Quoting Patrap:
The strongest of the convection is going ashore along the Mexico/Guatemala coast. I think we have landfall, if my eyes aren't mistaken.
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2839. Patrap
Dr. Masters discusses the Oil and Hurricanes in this interview from last Tuesday,on NOLA Radio..the spud show.

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Quoting IKE:


I guess they done put their glasses on at the NHC.


I agree on that. I saw it in pretty much that position about 2 hours ago. No Sunday morning landfall for this one.
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Quoting FIU2010:
miami, 8pm, not forget.
I won't. :)
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Quoting AstroHurricane001:


Plus with the Caribbean looking more like early September than early June, it has about three more months than usual to warm to maximum temperature.
September? That's a bit of an exaggeration.

September 29, 2009


May 29, 2010


*And keep in mind that that was in 2009, and we all know 2009 wasn't an impressive year, it even wasn't "average".
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2835. Patrap
Quoting FIU2010:


oh no, hwy would that happen, pat?


2 degrees F,,my mistake
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Quoting gordydunnot:
456 while you are here or anyone if you please. Are high subject to the same classification as lows specifically ull,mll,llc or are they pretty much top to bottom in the troposphere.


There are different types of highs.

You have shallow high pressures which only extend upward to about 600 mb the most. These highs are caused when cold air sinks to the surface and hugs it and since cold air is heavier than warm air, it creates high pressure. This type of high you would say is a low-level high pressure but we do not term them as such. The more familiar term is shallow high pressure. Examples include the North America High over Canada and the Siberian High over Asia.

We also have upper level highs caused by the expansion of heat in the tropics. These highs begin at around 500 mb and upwards. The subequatorial ridge of the tropics are example of this type of high. The high over Texas during July is another example of an upper high and the massive Tibetan high is the largest of them all.

You also have deep layer highs. These highs form from sinking air (subsidence) emanating from the outflow near the ITCZ and sinking towards the subtropics. These highs extend throughout most of the atmosphere and include the Azores High, Pacific High, St. Helena High, Australian High and the SE Pacific High.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2832. Patrap
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Quoting IKE:


I guess they done put their glasses on at the NHC.


They defininately could not have been ready for all the hybrid storms this winter if they so wished to classify any of them as subtropical.
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2830. scott39
Everytime i see new models on Agatha its got her going farther N into the GOM! I hope most of you are right about this thing crappin out on land or in the GOM! Then i read about an anticyclone acting like a suit of armor around Agatha protecting her from the big bad wolfs winds. Now i read that the steering winds are going to steer it more N and then NE.I hope most of you are right and this thing dies on land!
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Contest to name first oilycane of the season. May name BPcane.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
Quoting Weather456:


That's too far. The first major hurricane of 2010 is likely occurring in July if these conditions persist.


Plus with the Caribbean looking more like early September than early June, it has about three more months than usual to warm to maximum temperature.
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2826. KEEPEROFTHEGATE (Mod)


nice blow up startin
Member Since: July 15, 2006 Posts: 170 Comments: 53568
How much more similar can it get?




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I suspect if Agatha can at least hold together some kind of CoC like 90L did in 50kt shear, then it could potentially develop near the Eastern Seaboard with the help of low shear and SSts from the loop current.
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2823. Patrap
Quoting gordydunnot:
You better patent that one Pat. The news media or at least Bastardi will be all over that like white on rice.


I Like it too.

They steal all my junk..seems,

Im gonna get a good BP Lawyer.
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I would say the center of Agatha is making landfall as we speak.

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Quoting AstroHurricane001:


Wave right behind it is even more impressive.


What wave?
Member Since: March 10, 2010 Posts: 1 Comments: 7530
2820. Patrap
The Oil is going to increase the SST's up to 1-2 degrees Fahrenheit the Good Dr. says.
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You better patent that one Pat. The news media or at least Bastardi will be all over that like white on rice.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
2818. Patrap
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Quoting Levi32:


There's a possibility it may have aided in the formation of this particular wave, but I am not seeing a way to conclusively prove that. Regardless, it is an impressive wave.


Wave right behind it is even more impressive.
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Quoting CyclonicVoyage:
Aggie wasn't forecast to make landfall until tomorrow morning sometime.


It's speeding up.
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456 while you are here or anyone if you please. Are high subject to the same classification as lows specifically ull,mll,llc or are they pretty much top to bottom in the troposphere.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
Quoting WaterWitch11:
does anyone see what's potentially in play at this moment? i'm freaking out.

i don't have anything else to bake.


Agatha's remnants could affect the oil spill.
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Quoting AstroHurricane001:


But the upper level low and some convection could have survived? Same with Agatha. A LLC or two could develop from the remnant ULL.


Agatha is capped by an upper anticyclone, not an upper low.

Now the LLC will likely tear apart over the terrain of CA but because the mountains are below 5500 ft, the mid-level circulation will survive. Again the mid-level circulation may become disrupted under to much west to east flow in the subtropical jet. The subtropical jet will not allow either an upper anticyclone nor mid-level circulation to persist since the force of the winds is in a straight-line.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2812. Patrap
Im gonna go with Oil-Zilla,


Say it fast with a Japanese B-Movie accent.

It works.

Konichi-wa

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2811. Levi32
Quoting Weather456:


Do you release the subtropical jet stream is zonal and blowing at 40-50 knots while an upper anticyclone is vortex and blowing at 10-15 knots. The anticyclone will disrupt under that much zonal flow.


That's why the CMC makes no sense. It has the anticyclone buzz-sawing right through the Subtropical jet.
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If Agatha made landfall this early then she's taken the more easterly influence of the model spectrum. Watch for an Alma/Arthur setup.. if not still Agatha will deliver heavy rains and even worse, mudslides.
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Quoting AstroHurricane001:


Its anticyclone could protect it.


Do you release the subtropical jet stream is zonal and blowing at 40-50 knots while an upper anticyclone is vortex and blowing at 10-15 knots. The anticyclone will disrupt under that much zonal flow.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Make that 2 volcanoes , but they haven't closed all the airports in S. America yet.
Member Since: August 18, 2008 Posts: 0 Comments: 3113

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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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