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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I believe it means disturbance.
LO means Low I would think
DB means Disturbance
In other words the NHCs thinking that the center is still not well-defined is correct
28/2345 UTC 14.1N 95.9W T1.0/1.5 90E
28/1745 UTC 13.4N 94.7W T1.5/1.5 90E
Nope...watching the NBA.
yup and satellite confirms, 90E is getting less organized again
This system can't seem to get its act together enough
Look at my ASCAT pic:
How is that not well-defined? That's better than earlier.
But it will not be able to dampen waves created well out to sea where there isn't enough surface slick to stop them from forming. Then the mixing begins...
And the dense surface slick, covering square miles, will be staying about where it is until BP does something constructive, or at about 29 N. Very uncommon that we get very small hurricanes. (anyone know of any smaller than Camille in the northern gulf?)
Even if we got a little one, still would induce enough mixing that the surface oil would have an undetectable effect if any at all on the hurricane itself, again, in my honest opinion. Even the smallest cat 1 puts surface waters in motion. We all saw what happened when oil reached the loop current. A thin tendril stretched out over miles and miles. Moving water will do some things guaranteed to break up a solid slick.
It's DMIN, did the exact same thing last night.
It is elongated from NE to SW that is how
It was like that earlier, but notice how in the middle of the elongation, it makes a quick East to West cut-through.
yea not sure why he was referencing Dennis in 1981, completely different situation
DB - disturbance,
TD - tropical depression,
TS - tropical storm,
TY - typhoon,
ST - super typhoon,
TC - tropical cyclone,
HU - hurricane,
SD - subtropical depression,
SS - subtropical storm,
EX - extratropical systems,
IN - inland,
DS - dissipating,
LO - low,
WV - tropical wave,
ET - extrapolated,
XX - unknown.
If they start using XX we are in trouble.
WOW at auroras!
Right but before the last advisory, this has been known as a Low, now it is a Disturbance
Who are you testing?
Blop model.
Link
Or maybe it has eaten a hole in the warmer water.
Do disturbances have lows?
So if the slick persists as the eye of a hurricane pases over, the winds would be calm but the seas would be very high. Would oil under the eyewall pool upward into the space under the eye as oil floats upward and rises as it warms? Could the oil warm the air due to solar radiation and heat in the storm, producing the effect of strengthening or ERC-ing the storm's eyewall?
So the heaviest rains could hit close to the erupting volcano. Yikes.
Salina Cruz is a good distance away from the storm, in fact it is located within the cirrus overspread (CO).
CDO - Central dense Overcast
OBA - outer band area
ECT - embedded cloudtops
EP 90 2010052818 3 OFCL 3 129N 944W 30 1005 TD
EP 90 2010052818 3 OFCL 12 133N 937W 35 0 TS
EP 90 2010052818 3 OFCL 24 137N 929W 40 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 36 141N 921W 50 0 TS
EP 90 2010052818 3 OFCL 48 146N 915W 35 0 TS
EP 90 2010052818 3 OFCL 72 151N 913W 20 0 TD
Pretty defined tri-pole
This is completely outside of my experience. I have no idea, really.
In fact, everything related to hurricanes and oilslicks is pure conjecture based on some assumed parameters.
We have never been here before...
Wow, that looks almost like an angel rising out of hellfire.
Just south of NE
It was a mistake.
I know, I know...you all think otherwise, but this is not the same kind of oil as in the Exxon V. spill. It will break down quickly, especially if well dispursed.
If so, what is going on now?
Looks kind of scary....
No. They did not classify it, seems they were ready to and backed off.
Disclaimer from the ATCF site:
Users are also cautioned that the data in these files are subject to frequent revisions and can differ from information issued in official NHC products.
What is a tri-pole?
I realized a second ago that I messed up. I modified the post.
We've been quite dry for a while now, and this system doesn't seem to be bringing any precipitation. Just thunder and lightning...
(busy actually working)
Yep, all the heat is focused in the Tropics. Its only a matter of time now.
so DB is actually an upgrade from LO?
OFCL is running... is it a TD? For a second there, I wad like, "How long has this thing been tropical?"
Super Duper Megacane? Who knows. I'll post this link one more time before I call it a night. Dr. Masters had some great insight to the oil spill/hurricane relationship. He also gives us a sneak peek at his predictions for the upcoming season. Read it.
Later Stormsurgeon.
Dr. Masters comments
where's 25% on that map lol
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