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 MiamiHurricanes09:
Interesting, anxious to see what plays out.


Aye, same here... we will have to see!
Member Since: May 27, 2009 Posts: 0 Comments: 4436
3156. Dakster
Quoting AstroHurricane001:


Probably not an earthquake. The frogs are migrating during mating season and the large number could be the result of heavy winter rains.


Aren't Frogs the eleventh plague?
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3155. hydrus
Quoting Makoto1:
Here's a question for anyone who knows: How do you know which steering flow to use for a certain tropical cyclone? I know that it's deep if it's a deeper cyclone, etc., but how exactly do you tell what it is?
Tropical depressions and tropical storms are affected by the steering currents in the lower atmosphere. Mature hurricanes are steered by wind currents that are present in the upper levels above 35,000 feet or about 200 millibars.
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3154. EricSFL
Quoting MiamiHurricanes09:
Current Fatality Count


Costa Rica 0
El Salvador 1
Guatemala 12
Mexico 0
Nicaragua 1
--------------------
Total 14


Devastating, and still raining.
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Quoting Makoto1:
Here's a question for anyone who knows: How do you know which steering flow to use for a certain tropical cyclone? I know that it's deep if it's a deeper cyclone, etc., but how exactly do you tell what it is?


Here is the steering layer map.

If you look at the bottom of the map it tells you the pressure range of the cyclone that applies to it. If you click on each mb level at the top of the map and then look at the bottom you will see that as the height above sea level changes the intensity of cyclone that is steered by it also changes.

In order to understand what height above sea level each milibar reading is you need another graph that I will post shortly. For instance, 850 mb is approximately 5000 feet above sea level.

Hope this helps.
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Quoting MrstormX:


Well I was being a bit dramatic anytime now implies within 48 hours... I personally believe it will make it, though I doubt there will be any convection left. If however it retains a circulation center, it can always redevelop once it finds the right environment in the Atlantic. Since the model I use is showing this happening near the Eastern Seaboard, I suspect thats where a redevelopment could occur. Probably not in the Caribbean...
Interesting, anxious to see what plays out.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
In one week, the total rainfall from 90E was about 80 855 tons of water. Most of it fell in the Pacific Ocean. How did I arrive at this figure.

Well the surface precip rate over the past week was about 0.00027 kg per second, and since there are 604 800 seconds in a week, that is about 163 kilograms of precip in one week. But that is just the amount for one square meter. The area affected by 90E is 450 000 m^2 for a total of 73 350 000 kilograms of precip.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Current Fatality Count

Costa Rica 0
El Salvador 1
Guatemala 12
Mexico 0
Nicaragua 1
--------------------
Total 14
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting WaterWitch11:
someone posted this the other day:

Athens: Traffic was paralysed along a highway in northern Greece for several hours Wednesday after thousands of frogs suddenly jumped onto the road, startling drivers.

Drivers along the Egnatia Highway, which runs between the northern port city of Thessaloniki to the Turkish border on the Evros River, said the frogs appeared out of nowhere, causing a handful of traffic accidents and paralysing traffic.

Traffic police spent nearly two hours trying to clear the frogs from the highway.

Experts were at a loss to explain the bizarre phenomenon.


i think as long is there is no big earthquakes, i'll stop freaking out!

but i kinda doubt that one


Probably not an earthquake. The frogs are migrating during mating season and the large number could be the result of heavy winter rains.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
3148. EricSFL
Hey Patrap you're getting squished by two blobs on 3136. lol
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Quoting MiamiHurricanes09:
Really? You think it will make it to the Caribbean.


Well I was being a bit dramatic "anytime now" implies entering the atlantic within 48 hours... I personally believe it will make it, though I doubt there will be any convection left. If however it retains a circulation center, it can always redevelop once it finds the right environment in the Atlantic. Since the model I use is showing this happening near the Eastern Seaboard, I suspect thats where a redevelopment could occur. Probably not in the Caribbean...
Member Since: May 27, 2009 Posts: 0 Comments: 4436
3145. Makoto1
Quoting Levi32:


It can depend, but general estimations are given with the CIMSS Steering Maps, telling you approximately what layer would steer a TC of a certain intensity.


Thanks, I'll be sure to note that. I'm glad I have a place to go with questions like this.

So I take it that if we're trying to figure out the direction the mid-level remnants of a system, take Agatha just as an example, will go, I look a little higher up than what a typical 1000 mb surface low would usually be?
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Quoting alexhurricane1991:
I dont know if anyone knew this but guatamala has 14 inches of rain in just a few days and its still raining this could be bad im praying for those guys down there even if this storm is so called "Weak" its a killer.


An INVEST killed over 120 people in El Salvador last summer, and Mitch killed 15,000 people in Honduras after weakening to a depression from a cat. 5. Remember that heavy rainfall and weakening storms can be dangerous, especially in combination with volcanic flanks and lahars.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
3143. Dakster
Quoting kmanislander:


Well, all I can say is not many left ! LOL


Kman - Do you celebrate something this weekend as well??? Or just doing a BBQ because it is the weekend.. It is "memorial day" weekend in the U.S.
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Quoting kmanislander:


Well, all I can say is not many left ! LOL
LOL.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
3140. Patrap
Quoting kmanislander:


Well, all I can say is not many left ! LOL


How was the Rose'..?
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I think it will make it in the caribbean
Member Since: June 13, 2009 Posts: 2 Comments: 10852
3138. USSINS


CIMSS's new, experimental "IR/WV Difference" graphics.
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Member Since: September 2, 2009 Posts: 130 Comments: 21091
3136. Patrap
Man its under going a big Up pulse kman..Orographic Lifting is squeezing her Like a Fat Cow at Morning..
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3135. EricSFL
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Quoting MiamiHurricanes09:
Sadly. How where your baby back ribs?


Well, all I can say is not many left ! LOL
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3133. Levi32
Quoting Makoto1:
Here's a question for anyone who knows: How do you know which steering flow to use for a certain tropical cyclone? I know that it's deep if it's a deeper cyclone, etc., but how exactly do you tell what it is?


It can depend, but general estimations are given with the CIMSS Steering Maps, telling you approximately what layer would steer a TC of a certain intensity.
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Quoting kmanislander:


TD before midnight was my call at 4pm.

However, now we see the convective blow up starting that will dump torrents of rain over the mountainous terrain. A disaster unfolding
Sadly. How where your baby back ribs?
Member Since: September 2, 2009 Posts: 130 Comments: 21091
3131. Patrap
Agatha Floater - Funktop Color Infrared Loop
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Quoting MrstormX:
Agatha is skirting through Central America quicker then I anticipated... it could be in the Caribbean or in between the GOM and Caribbean anytime now.
Really? You think it will make it to the Caribbean.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting MiamiHurricanes09:
Agatha is now officially a TD.


TD before midnight was my call at 4pm.

However, now we see the convective blow up starting that will dump torrents of rain over the mountainous terrain. A disaster unfolding
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Agatha is skirting through Central America quicker then I anticipated... it could be in the Caribbean or in between the GOM and Caribbean anytime now.
Member Since: May 27, 2009 Posts: 0 Comments: 4436
Quoting Patrap:




The vortex now over the Mississippi-Louisiana border continues to drift southwest.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
3126. Patrap


Deep Water Oil Drilling is changed forever.

Oil-zilla is out there...and the Season has begun in Ernest.

Nature is setting us up for a serious wake up call.

Maybe a lot sooner than anyone thought.

Drill,Baby,..drill.


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3125. Makoto1
Here's a question for anyone who knows: How do you know which steering flow to use for a certain tropical cyclone? I know that it's deep if it's a deeper cyclone, etc., but how exactly do you tell what it is?
Member Since: Posts: Comments:
KEY WEST — About 12 miles north of Dry Tortugas, the crew on the Mattie Fay hauled up their shrimp catch and got oil.
NAPLESNEWS.com
Fishing crew reports tar balls in net
By KATY BISHOP
Posted May 24, 2010 at 7:35 p.m.
Tar balls were tangled in their nets with the shrimp. There was tar on the shrimp, tar on their boots, tar on their gloves.

“We just come on in after that,” said Brian Williams, 30, a member of the Mattie Fay crew. “We didn’t drag no more. Once we saw that, we pretty much wrote it off.”

-the article goes on from there...ugly ugly ugly!!!
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Quoting naplesdreamer28:
The oil live video feed is cutoff! BP is hiding way to much.

? Works for me...

http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/homepage/STAGING/local_assets /bp_homepage/html/rov_stream.html
Member Since: August 16, 2007 Posts: 6 Comments: 12461
This page goes way too quick, its impossible to get a comment heard without like 5 others replacing it.
Member Since: May 27, 2009 Posts: 0 Comments: 4436
3121. Dakster
Quoting Weather456:
Deep layer ridge pushes itself into the Caribbean as far west as 85W. Because the LLC will become disrupted over terrain we can ignore the shallow layer flow (but it basically shows the same thing) and concentrate on the deep layer flow.



So you would go with the BAMD instead of the BAMS for steering?
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new map

Member Since: June 13, 2009 Posts: 2 Comments: 10852
The oil live video feed is cutoff! BP is hiding way to much.
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The head of Rio Tinto Mining (#2 Mining group in the world) has their hands in his pockets with consulting deals for him...he will do nothing that will cut off their games.
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3117. EricSFL
Pretty nasty thunderstorm rolling southward over the western suburbs of Miami-Dade...
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I agree patrap
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3115. Patrap
Quoting SiestaCpl:
I am an American Indian...we know the Interior department all too well...MMS is another face of the beast...we refer to the BIA - "Bureau of Indian Affairs" as "Bastards In Action"...


Salazar..he wears a nice hat,but hes clueless and way too close to Oil.

I think he should get the boot..but not on his neck
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Quoting AstroHurricane001:


But you'll have to be fast, you might have to go through a whole page of comments in just two minutes to keep up on some days!
I hate that. I'm content with 1 post every minute. Not 5 or 10.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
I am an American Indian...we know the Interior department all too well...MMS is another face of the beast...we refer to the BIA - "Bureau of Indian Affairs" as "Bastards In Action"...
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Quoting Chicklit:
I haven't checked the center coordinates. Is that an eye or an optical illusion?
No that's a medium sized lake over Guatemala :).
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting alexhurricane1991:
I agree going to be a hectic year on the blogs i guess i picked a good year to start posting.


But you'll have to be fast, you might have to go through a whole page of comments in just two minutes to keep up on some days!
Member Since: August 30, 2008 Posts: 8 Comments: 2835
3108. Patrap
Quoting SiestaCpl:
BP operates just as most of the majors do in the mining industry..oil producers and mining groups consider everything under our feet theirs and often forget that we must still live on the ground they disturb..or ruin...


and MMS rolled like dat as well, till now
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BP operates just as most of the majors do in the mining industry..oil producers and mining groups consider everything under our feet theirs and often forget that we must still live on the ground they disturb..or ruin...
Member Since: Posts: Comments:

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About

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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