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 FIU2010:
miami, should we monitor this situation?
Well if more models jump aboard with this solution yes. But I doubt, if it does happen, that it will be intense. Way too much shear for development there.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
you will have to reach a long way. He only listens to reason.
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855. xcool
90E MOVE NNE OR NNW
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Quoting Floodman:
Okay, that's enough chaos and mayhem for one day...


LOL
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853. xcool


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2009 NOAA May forecast.
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Quoting MiamiHurricanes09:
LOL, my bad.


Its all good lol
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Hurricanes 101:
That last one wasnt for you sir. I was trying to reach out to Floodman.
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Quoting Hurricanes101:


that is what I said lol GFS and NOGAPS are showing a weaker system
LOL, my bad.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
847. xcool
WT8888 GFS
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Beautiful ascat pass from noon

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Floodman:
If it does develop there are so many land areas the system could strike. Limiting it to a certain location reduces your chances.
Member Since: Posts: Comments:
Thanks Ag. "Conditioner". I was trying to remember the name of that contraption. My brother tried to get me set up with one a looong time ago when I was living at the end of the line and had to be careful to save to my 3.5" floppy disk when the lights were at full bright. Prohibatively expensive at the time. Saw one not too long ago at one of the local gizmo shops for neighborhood $300 if memory serves. Claimed reasonabl back up time if total outage, stable output and surge suppression. I would probably own one if I were gear dependent.
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Quoting MiamiHurricanes09:
On the contrary, the CMC is showing the most intense solution.


that is what I said lol GFS and NOGAPS are showing a weaker system
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The organization of 90E has improved significantly throughout the day. I suspect its nearing TD status.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
we I have already disregarded them already
Member Since: June 13, 2009 Posts: 2 Comments: 12716
Quoting MiamiHurricanes09:
Agreed. Could be very soon.


Hopefully before light there fades... id like a visible picture for Wikipedia... rather then IR.
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Okay, that's enough chaos and mayhem for one day...
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kuppensup take a look


Prediction for the 2009 season from NOAA was 9-14
Prediction for the 2010 season from NOAA was 14-23
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Hmm, tropical storm looking possible starting +80 hours.

Member Since: May 27, 2009 Posts: 0 Comments: 4438
835. IKE
Quoting Hurricanes101:


The conditions setting up for this season are much more favorable than they were at this time last season

also last season we were heading into an El Nino, this year we are heading into a La Nina.


If all of the "experts" blow this years forecast in the Atlantic...so goes some of their cred.

I can't see them all being wrong. I think it will be an above average season in the Atlantic.
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No-I didnt mean you I was refering to the Sussener
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Quoting KEEPEROFTHEGATE:
90e will become a depression within next 12 to 14 hrs from now
Agreed. Could be very soon.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
90e will become a depression within next 12 to 14 hrs from now
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Quoting kuppenskup:
I know everyone is saying the conditions are right for an active season but before the Beg of the season last yr our so called experts called for an above average yr. I forgot the exact #'s but it wasnt until the end of Aug when they changed their predictions. Sorry I just dont buy it.


NOAA forecasted 9-14 Named Storms last May which is below the average of 14.4NS since 1995 when the AMO went into a warm phase.
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Quoting IKE:
NOGAPS isn't that different then the CMC and GFS as far as track through 4 days wanting to bring it north some.
Quoting wunderkidcayman:
hey MiamiHurricanes09 please disregard the 18Z model runs
Nobody should disregrd any model run i do agree that the 12z and 0z runs are better but to say to totally disregard the others is foolish no offense to anyone.
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Quoting MrstormX:
I'm waiting for the 18z graph.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
828. IKE
Models can be trends. Trends today are further north with 90E, after crossing Central America. See what Saturday morning models say.

I've noticed a significant trough in the eastern USA in the 7-10 day time period. I've also noticed the 6-10 day outlook is for below normal temps in the east.

Maybe 90E does get drawn into the GOM? Not sure what's left of it though, at that point.
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Quoting Hurricanes101:


GFS and NOGAPS appears to bring a system into Florida as well now, not as instense as the CMC though
On the contrary, the CMC is showing the most intense solution.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Hurricanes101:


GFS and NOGAPS appears to bring a system into Florida as well now, not as instense as the CMC though


They have compensated for the increase in vertical shear.
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Member Since: May 27, 2009 Posts: 0 Comments: 4438
Quoting kuppenskup:
I know everyone is saying the conditions are right for an active season but before the Beg of the season last yr our so called experts called for an above average yr. I forgot the exact #'s but it wasnt until the end of Aug when they changed their predictions. Sorry I just dont buy it.



So it's a gut feeling, is it? LOL
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Quoting kuppenskup:
I know everyone is saying the conditions are right for an active season but before the Beg of the season last yr our so called experts called for an above average yr. I forgot the exact #'s but it wasnt until the end of Aug when they changed their predictions. Sorry I just dont buy it.


The conditions setting up for this season are much more favorable than they were at this time last season

also last season we were heading into an El Nino, this year we are heading into a La Nina.
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Quoting Weather456:
I saw the CMC run bringing an intense cyclone into Florida...I would like to believe the model but it has the cyclone under shear...its not being reasonable.
Not at all. GFS also showing this (no surprise) and the NOGAPS starting to show the same thing. I might just start jumping on the bandwagon but it shows the system strengthening in the middle of the subtropical jet stream, not gonna happen.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I know everyone is saying the conditions are right for an active season but before the Beg of the season last yr our so called experts called for an above average yr. I forgot the exact #'s but it wasnt until the end of Aug when they changed their predictions. Sorry I just dont buy it.
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Quoting Weather456:
I saw the CMC run bringing an intense cyclone into Florida...I would like to believe the model but it has the cyclone under shear...its not being reasonable.


Looks like back to the bad old days for the CMC; that or it's a momentary lapse...thought they had that fixed...
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Quoting Weather456:
I saw the CMC run bringing an intense cyclone into Florida...I would like to believe the model but it has the cyclone under shear...its not being reasonable.


Agree.
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Quoting Weather456:
I saw the CMC run bringing an intense cyclone into Florida...I would like to believe the model but it has the cyclone under shear...its not being reasonable.


GFS and NOGAPS appears to bring a system into Florida as well now, not as instense as the CMC though
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Here's a non-earthquake explanation for the frogs in Greece: the frogs are migrating and it's their mating season, and the vast number of frogs is the result of winter rains.

A volcano erupts in Guatemala...Link

...and Ecuador. Link I guess we have what we need to temporarily slow global warming: tropical volcano eruptions.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Good Evening everyone!
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I saw the CMC run bringing an intense cyclone into Florida...I would like to believe the model but it has the cyclone under shear...its not being reasonable.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting kuppenskup:
There are two chances-Slim & None


And your reasoning is based on what, son? Put up or shut up
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Quoting atmoaggie:

For me, it's 10:30 on 5 hours sleep. G'Nite.
Good night!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting wunderkidcayman:
hey MiamiHurricanes09 please disregard the 18Z model runs


Why?
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Quoting wunderkidcayman:
hey MiamiHurricanes09 please disregard the 18Z model runs
I'm not going to disregard the 18z model runs. Each model run is important because if you just disregard whatever run you want you're not going to know if there will be consistencies or not.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting kuppenskup:
There are two chances-Slim & None


That wasnt the point of the question, I am just curious as to what others feel is the MOST likely of the 3

I dont think any of the 3 will happen either, but I still chose one of them
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Quoting MiamiHurricanes09:
LOL. It's only 5:30 PM CDT (It's 6:30 for me).

For me, it's 10:30 on 5 hours sleep. G'Nite.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
hey MiamiHurricanes09 please disregard the 18Z model runs
Member Since: June 13, 2009 Posts: 2 Comments: 12716

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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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