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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Whats latest on 90E??? is it gonna affect the US in any way????
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?? Dr Lyons quitting weather channel???
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I think 90E could be trouble for the Gulf Coast..Real Trouble!
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Quoting lickitysplit:
Sounds like both the top kill and the junk shot failed. Ug.


:(
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1152. pottery
Quoting RTLSNK:
Hi Pottery, looks like we all said "surface" at the same time. :)

We just all on the ball here, man!
I need more manpower around here these days, the grass, weeds, everything is growing faster than we can keep it back.
Thought I saw a Tiger stalking a Elephant in the yard the other day. Coulnt be sure. Too much bush....
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Quoting AllStar17:
Does anyone have any thoughts on Rick Knabb being the new Hurricane Expert at TWC? I did like Dr. Lyons and will miss him.


I have not seen him in action as of yet. But the TWC was dying before, when Steve left....that was the nail that sealed the casket.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1150. KEEPEROFTHEGATE (Mod)
Quoting WinterAnalystwx13:
I made this graphic really quickly.

and you really should stop scaring people nothing has been detemined yet with the system 90e
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Sounds like both the top kill and the junk shot failed. Ug.
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If you noticed, the white chunks got larger as the headed for the surface.
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i swear i just saw that the cam was ON the ocean not under.
Member Since: August 11, 2008 Posts: 3 Comments: 1579
Quoting AllStar17:
Does anyone have any thoughts on Rick Knabb being the new Hurricane Expert at TWC? I did like Dr. Lyons and will miss him.

He knows his stuff. He worked with the NHC for 14 years. And Yes, we will miss Dr. Lyons expertise. :(
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1145. pottery
Quoting ChillinInTheKeys:
This could be what it has looked like @ 1500' all along.

Could be. Not good for swimming in...
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1144. RTLSNK
Hi Pottery, looks like we all said "surface" at the same time. :)
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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
Member Since: March 10, 2010 Posts: 1 Comments: 7397
1142. RTLSNK
Now they are showing all the vessels on top of the surface.
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Quoting pottery:

The riser has come apart??
Looks like oil and debris, which could be the 'junk' they have been injecting.
Does not look good at all.

What I am seeing in on the surface: http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/homepage/STAGING/local_assets /bp_homepage/html/rov_stream.html

Yeah, late with this comment.
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This could be what it has looked like @ 1500' all along.
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1138. pottery
Quoting ChillinInTheKeys:
They were pulling up the robot.

OK OK OK that explains that! Whew.
Looks like it's on the surface now.
Hi Snake!
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Does anyone have any thoughts on Rick Knabb being the new Hurricane Expert at TWC? I did like Dr. Lyons and will miss him.
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Quoting ChillinInTheKeys:
It looked like they were just pulling it up to clean it maybe. Looked normal at the time.

They need windshield wipers on the camera lenses to keep them clean.
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They were pulling up the robot.
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1134. RTLSNK
Quoting pottery:

Were you looking at the vid when this started? Last time I looked an hour ago, all seemed well.


Same here, when I looked at it last time the view was of a part of the BOP with a hose attached to a fitting of some kind. When I went back the ROV was showing the view you see now. I don't see the BOP at all now.
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Quoting dsenecal2009:
Extreme wind and thunderstorms just knocked over my bonsai tree and two cactuses. I would estimate at least 35mph winds consistently for the past hour in the west 610 loop. I am in deep uptown Houston, a quick jog from Galleria, and we are seeing some very severe weather all of a sudden. It is a huge surprise to all forecasters involved..

It is quite surreal here in my apartment complex, with very heavy rains whipping around the courtyard, i have been pelted with marble-sized hail.


We got a smaller but similar one here in southeast Houston near NASA.
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1132. pottery
Quoting ChillinInTheKeys:
It looked like they were just pulling it up to clean it maybe. Looked normal at the time.

What were they pulling up?
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I wish we could view the actual feed itself instead of a video camera recording a monitor. The quality is not very good, and you are stuck with whichever feed they decide to point the camera at. Or in the case of showing the whole panel, a very tiny version of all the feeds.
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Extreme wind and thunderstorms just knocked over my bonsai tree and two cactuses. I would estimate at least 35mph winds consistently for the past hour in the west 610 loop. I am in deep uptown Houston, a quick jog from Galleria, and we are seeing some very severe weather all of a sudden. It is a huge surprise to all forecasters involved..

It is quite surreal here in my apartment complex, with very heavy rains whipping around the courtyard, i have been pelted with marble-sized hail.
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It looked like they were just pulling it up to clean it maybe. Looked normal at the time.
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First image - GFS MSLP/PRECIP valid 8PM EDT tonight...rainfall maxs on the right side of storm as was illustrated earlier.

Second image - SKEW-T image of the marked blimp on the first image showing a deep layer of moisture. Such a vertical profile is indications of torrential rains.





Member Since: July 24, 2005 Posts: 407 Comments: 19076
1127. pottery
Quoting ChillinInTheKeys:
Looks like the gases were expanding as they rose which caused the to cool and make chunks of ice.

Were you looking at the vid when this started? Last time I looked an hour ago, all seemed well.
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Looks like the gases were expanding as they rose which caused the to cool and make chunks of ice.
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1125. pottery
Quoting HurricaneObserver:

I looks like a mess, and there are no referance point to get an orientation. Stuff is moving both up (bubbles?) and down (mud?) in the feed.

The riser has come apart??
Looks like oil and debris, which could be the 'junk' they have been injecting.
Does not look good at all.
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1124. Dakster
W456 - Nice photos...

One day I plan to travel the Earth - for now one must work to pay the basic bills..
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Quoting Weather456:
I uploaded some pics, all are welcomed to rate them...just click on the image.









They are all gorgeous and I rate them A+. St Kitts looks very beautiful.
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Quoting cg2916:
Just now found this:

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

NOAA%u2019s 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%u2019s Eastern Pacific outlook are the atmospheric conditions that have decreased hurricane activity over the Eastern Pacific Ocean since 1995 (opposite of the Atlantic) %u2013 and the fact that El Nio has faded.

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

well, the thunderstorm cloud tops tend to flow out and this is what causes the shear of the atlantic in El Nino years. Concentrated heat in the Pacific promotes lift and therfor more TC. The increased activity leads to decreased atlantic activity. So in a sense, this is just another issue pointing towards an active atlantic season.

edit: maybe this is a bit misleading. When I said "cloud tops" I mean the air associated with the clouds. Of course as the air sinks (subsides) away from the updrafts over the EPAC, the clouds will of course disappear.
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Quoting cg2916:


Just hit DMIN, that's all.
I don't think he is refering to 90E but the pipe or whatever in the GOM
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was getting tidbits from a few engineer friends working in the gulf. Now, everyone has lockjaw. I think some frustration is setting in with 72hrs of work.
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Quoting pottery:

Looks like the thing has come apart..............

I looks like a mess, and there are no referance point to get an orientation. Stuff is moving both up (bubbles?) and down (mud?) in the feed.
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Quoting Dakster:
W456 - What are the photos of? (geographically speaking)


saint kitts....the exact locations are on the links
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Just in case anyone is a little depressed.http://www.youtube.com/watch?v=Bmxyj6iInMcLink
Member Since: August 18, 2008 Posts: 0 Comments: 3112
1116. cg2916
Quoting pottery:

Looks like the thing has come apart..............


Just hit DMIN, that's all.
Member Since: December 21, 2007 Posts: 13 Comments: 3035
1115. 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.
Member Since: December 21, 2007 Posts: 13 Comments: 3035
1114. Dakster
W456 - What are the photos of? (geographically speaking)
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1113. pottery
Quoting hydrus:
Now there saying it might be Sunday before they know if it is sealed.....

Looks like the thing has come apart..............
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Quoting KEEPEROFTHEGATE:
well its tropical low then tropical disturbance then tropical depression then tropical storm and finally hurricane

and then apocalyptocane
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Quoting KEEPEROFTHEGATE:
well its tropical low then tropical disturbance then tropical depression then tropical storm and finally hurricane


ok cool lol, just was curious
Member Since: March 10, 2010 Posts: 1 Comments: 7397
1110. KEEPEROFTHEGATE (Mod)
Quoting Hurricanes101:


so DB is actually an upgrade from LO?
well its tropical low then tropical disturbance then tropical depression then tropical storm and finally hurricane
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Here in Puerto Rico,we are getting hammered with a big rain event with numerous flood advisories and warnings.

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Quoting WinterAnalystwx13:


yay!!!

?
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1107. cg2916
Quoting nrtiwlnvragn:


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

Getting closer, though
Member Since: December 21, 2007 Posts: 13 Comments: 3035

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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.