Dr. Jeff Masters' WunderBlog

Loop Current Eddy cuts off; oil danger to Keys now greatly reduced
Posted by: Dr. Jeff Masters, 2:24 PM GMT on May 28, 2010 +3
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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3951. atmoaggie 2:55 PM GMT on May 30, 2010    
Quoting nrtiwlnvragn:


Link

Has not run recently, but does during the season.

Right, I knew about that one...forgot.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
3952. hydrus 3:01 PM GMT on May 30, 2010    
Quoting AussieStorm:

Who????
She is a meteorologist at The Weather Channel.
Member Since: September 27, 2007 Posts: 1 Comments: 14252
3953. Xyrus 3:02 PM GMT on May 30, 2010    
Quoting pottery:

To a large degree, yes.
I still demand that electricity is cheap, gas is far cheaper than rum, and that plastic bottles cost nothing.
Dont raise any prices, or I will vote you out. Simple.


When it comes to "What's Best" vs. "What's Best For Me", "What's Best For Me" usually wins. Until we change that we will continue to get the government that we deserve.

I agree that there should have been a larger response by the government, however the government's initial response was based on what BP told them (which at best could be considered a gross underestimation). When the real magnitude became apparent it was too late.

I think one big lesson here is that corporations will always act in their best interests (we should have learned this by now), especially in situations like this where damage control is priority one. We should ALWAYS assume the worst and respond accordingly. Sure, it may end up being overkill, but in situations like this it is far better to overreact at the beginning than discover later that the problem is worse than everyone thought.

Today I was just reading an article about how BP knew there were issues even further back than was currently known and yet still continued to press onward. BP should be dismantled with it's assets sold off to other companies, and everyone responsible for the chain of decisions (those who ignored the reported warnings and problems) leading up to this disaster should be imprisoned in facilities close enough to the areas affected where they can go out in prison jumpsuits to clean up the mess.

~X~
3954. Grothar 3:05 PM GMT on May 30, 2010    
Quoting atmoaggie:

Dare I say it? Oh, alright.

Could it be that all of the available environmental lobbying, legislation, attention, and even voter interest has been exhausted by AGW for the last 10 years all the while common sense legislation, with clear, positive results have been neglected entirely. And over sight by the environmental watch dogs has instead been getting the message out about cap and trade, of late, IPCC before that.

I have said before that since we cannot do without fossil fuels right now, we should be effectively regulating industries that lead to environmental pollution while funding alternate energy research until the time comes that we can do without crude oil.

Is this disaster a direct result? Probably not. Is it an indirect result of ALL of the think-tanks trying their level best to convince a populace and their representation that we need to arbitrarily raise the costs of maintaining our standard or living? And no one is overseeing what environmental concerns exist from drilling in deep waters without the ability to close an open well? Possibly.



You are 80% correct, as usual. You know I could never agree with you 100% atmo. LOL
There is much less lobbying on AGW than you would be led to believe. Rather, it is the lack of lobbying on the rebuilding of our infrastructure that has been neglected and the oversights on the energy industry, with which I totally agree with you. We simply cannot survive without oil at this time and that is a fact. How we control it is of vital interest to the entire world. (By the way, how is your buoy watching coming?)
Member Since: July 17, 2009 Posts: 56 Comments: 19515
3955. sarahjola 3:08 PM GMT on May 30, 2010    
Quoting kimoskee:
Hey Pottery, (or any one else who may want to answer) With no end in sight to the oil leak, should the islands start worrying about their beaches specifically Jamaica and Cayman?

their is an end in sight. its august. lol! that's forever away in this situation. but i don't think i would worry about it until it gets close and is inevitable that its going into the loop current. and i think i heard it on here that its not looking like its going to happen now. i may be wrong on that, correct me. but really maybe all should get a plan in place to fight it off if it does come your way. i would like to see a million boat owners/americans get together and circle the spill and just fight it like it was terrorist trying to invade us. that would be awesome! and when the feds or the coast guard try to stop them, they scream WOLVERINES!!! and take off into the gulf. sorry, just watched red dawn. lol! get prepared early. just in case.
Member Since: September 10, 2008 Posts: 0 Comments: 1291
3956. wunderkidcayman 6:10 PM GMT on May 30, 2010    
hey guys I am finding somthing weired with the remnants of Agatha
#1 Most of the heaver clouds and showers are moving more eastward
#2 The strongest vort is between Honduras, Guatemala, and Belize going into the GOH
#3 the (TCFP)=Tropical cyclone formation prob is very much good in the area
#4 But the 700-850 mb Mean Wind Analysis (TC Sfc Pressure Range 1000-1010 mbs) is taking it north
#5 BUT at the 500-850 mb Mean Wind Analysis (TC Sfc Pressure Range 990-999 mbs)
it is going ENE

so any ideas the graphics as follows









Member Since: June 13, 2009 Posts: 2 Comments: 5406
3957. aspectre 2:14 PM GMT on May 31, 2010    
Other major US-affecting offshore blowouts averaged 8,000to10,000barrels per day over 10days at Santa Barbara, and 11,000to12,000barrels per day over 295days at Ixtoc I, Gulf of Mexico.
Initial spill rate at Ixtoc I was ~30,000barrels per day.
The ExxonValdez wreck spilled ~11million gallons or ~262,000barrels in total.

Three different methodologies used by UnitedStatesGeologicalSurvey assessment teams have independently arrived at a minimum spill rate of 12,000barrels per day:
with the surface survey team coming up with 15,500plus-or-minus3500 barrels per day;
the plume-source measurement team coming up with 18,500plus-or-minus6500 barrels per day;
with the third team's study as yet incomplete and its methodology remaining unannounced.

Using the newly agreed-upon minimum rate of 12,000barrels per day, the DeepwaterHorizon spill will have released two times as much as the ExxonValdez shortly after noon on 3June2010.
Using the 17,000barrels per day average of the two released USGS studies, the DeepwaterHorizon spill will have released three times as much as the ExxonValdez before dawn on 6June2010.

In 2005, TropicalStorm Arlene reached near-hurricane strength in the Gulf of Mexico on June10th. And passed near what is now the DeepHorizon spill area before making landfall at the extreme western end of the Florida panhandle on June11th.
Comparisons with the day before TropicalStorm Arlene began spinning on 8June2005

30May2010

7Jun2005

30May2010

7Jun2005

30May2010
Member Since: August 21, 2007 Posts: 0 Comments: 4846

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About JeffMasters
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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