Loop Current Eddy cuts off; oil danger to Keys now greatly reduced
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
Reader Comments
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Well yes in most of the GOM but the southern regions bordering the Caribbean Sea, are not usually affected by early season shear. I consider this to be the only alleyway where Agatha would have a chance of redevelopment. I haven't had a chance to check shear values yet but if it is under 25kts I say there is a 20% chance. My favorite model, the GEM corresponds with my suspicions. The latest run at 12z shows Agatha's remnant moisture entering this alleyway as soon as 48 hours and begins to redevelop it by 72 hours. By 96 it is once again a weak tropical system of 1007mb near Sanibel Island, Florida. Eventually it becomes a borderline Category One hurricane by 120 with a pressure of 996mb and falling near South Carolina. With an eventual landfall near Washington D.C. as a 992mb storm.
84
120
With deep layer ridging pushing into the Caribbean, not much can go east. North it is.
Check the MSLP box
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...
Is that wave the remnant of Cyclone Bandu?
2km Storm Relative IR Imagery with BD Enhancement Curve
Topography is another factor that aids in easterly wave genesis.
i don't have anything else to bake.
24 years?! You might as well declare the entire Gulf a dead zone, fill it with red tides, and pump in 100 billion jellyfish!
Agatha Floater AVN Color Imagery Loop
August is looking more and more everyday as the first REAL chance to stop this thing. I can't even fathom the amount of oil that will be in the GOM and other parts of the surrounding areas by that time, it's sickening.
Yeah Bandu's vort max got lost over the Ethiopian highlands, the eastern-most birthplace of tropical waves.
Its not 90E
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.
I see the storm is also starting to make a northerly turn, which implies to me that there is a lesser chance of harm in the Atlantic.
Agatha,"Moorehead",,or Endora, wasnt that Darren's MIL on Bewitched ?
aren't there websites that have 10-day satellite loops? If so, you might be able to catch how that wave came to pass
That's too far. The first major hurricane of 2010 is likely occurring in July if these conditions persist.
I guess they done put their glasses on at the NHC.
I bet they been watching da Plume,..or the BP PC on TV..
August is looking more and more everyday as the first REAL chance to stop this thing. I can't even fathom the amount of oil that will be in the GOM and other parts of the surrounding areas by that time, it's sickening.
er,,he was talking about the Oil being stopped,not when a Cane forms .
considering they were expecting landfall late night tomorrow..
1000mb low moving NE/NNE at atleast 8mph, the question now is if it can survive the terrain..
I already did that. That is also a close call as the Ethiopian highlands (9,000ft high in spots) disrupted any organized cloud pattern that tried to cross them. Thus, it is again hard to tell whether Bandu had any influence.
I think you were spot-on. The heavy rainfall is concentrated over the Pacaya volcano!
There is a gradual decrease in shear, although it is probably higher then I expected. If it can hold together at all.. then it could potentially become a problem for the Eastern Seaboard where shear in some places is 0. It isn't impossible when you consider that 90L survived decently under 50kt shear, its more so a matter of Agathas forward speed, and passage over the mountains. Its not looking to likely though in the GOM, I think its only real chance would be near the Carolinas (which it would be hard pressed to make it too).
I know it is, that's the outlook on the relief wells. Many, Many areas, countries ect.. are going to feel it when you start tossing in an extreme hurricane season. This is a compounding series of unfortunate events that we won't know the final outcome to until they are realized, that's the toughest part.
What's ADT?
If you use the wavetrack loop from CIMSS for vorticity it doesnt seem that any piece of Bandu is caught up in this wave
Its anticyclone could protect it.
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.
:(
Working out the winter bugs, she got a push from something, that's for sure. I am surely no expert but, that was a pretty gross error.
It's wobbling a bit, but formed an eye at landfall.
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