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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Thanks Sweetie. Yes, I want rain for Caymans. Just really fear you all are going to get too much! goodnight, really, this time.
It looks like they had a snowstorm down there. :-)
Pretty heavy shower taking place here.
I hope something really bad didn't happen...something they don't want anyone to see yet.
It's a relatively small eruption in the scheme of things. The ash plume is only about 5000' high.
The water or the oil to cool? You mean the operation is actually forming subsea clathrates?!
Warm SSTs are always in the the tropical EPAC regardless of La Nina or El Nino. The reduce activity has mainly to do with increase activity over the Atlantic which has a direct effect on activity in the EPAC. Plus La Nina promotes downward motion over the EPAC and 200 mb westerlies increases.
We receive 36" a year in North Central TX, about 14" falls in Mar-May.
As El Nino faded to Neutral/La Nina, the regular and copious rains basically stopped.
In Feb we has rain every 2 1/2 days like clockwork.
In May we have rain once every 1 1/2-2 weeks, not a good sign.
All our reservoirs are between 95-100% full, due to very heavy winter rains.
With our normal dry summer, by mid Sept we will have them at 85% capacity.
The US Army Corps of Engineers run our 14 reservoirs, they supply water to about 8 million people in North and Central TX.
We have strict watering rules all over our region. One dry year is no problem, however 2 dry years, the "fun" starts, with strict outdoor water usage rules, complete with large fines :O)!!
Ah, okay. Thanks.
The question is are you doing shots? ;)
Hey all.
What makes you think the storm will curve northward toward Deepwater Horizon and Louisiana instead of eastward towards Florida? Where will the second tropical storm in the Caribbean come from? If two storms actually do form in close proximity then there could be a complex Fujuwhara interaction complicated by the northeastward Caribbean outflow, troughs reaching the Gulf and high pressure in the West Atlantic.
I cant find any video on CNN ! Everything was fine earlier. Are they running the vids?
Can you link?
Guatemala Pacaya volcano eruption
Guatemala, Honduras, El Salvador are fairly poor countries. I sure hope they have gotten word out to the natives in the mountainous villages, because serious and life-threatening flash flooding appears imminent!!!
My annual rainfall is about 7 feet. DDR gets about 9. Some areas of the Northern Range get 12.
And MOST of it falls in the rainy season, June to Dec.
This May has been record wet so far. And it only STARTED to rain on the 14th.
MARK
13.8N/93.9W
MOVEMENT
QUASI-STATIONARY
There is a WV vortex currently on the border of Arkansas and Mississippi with thunderstorms on its east and south sides rotating southwest (toward Houston)!
Possible TD or TS impact on SW Florida.
Must be nice to get 84" of rain a year!! The most we've had was 53", the least I believe is 15".
About 200 miles to our west, they see 20" of rain a year, 200 miles to our SE gets about 60".
Be careful what you wish for.
I warned you. :)
OK the feed is back up.
The low pressure and high precipitation forecast by models for the hurricane season has begun. And any storms heading eastward while there is a trough in the Mona Passage would threaten Hispanola.
Do you think the Calabash Tree knew it was gonna be real rainy?? U Betcha!
Where's the volcano in relation to 90E?
Ridges usually force a storm westward, while troughs usually mean they cut northward into the Bermuda high and out to sea.
In 1999 I measured 93.5", and in 2001 it was 50.5"
But 2001 was a complete anomaly. The 15 yr average (including 2001) is 77.5"
Lots of rain over Venezuela...and a trough/front over Costa Rica?
Without a Doubt. LOL
The exact length as my username!
Hi there
Yes it's exciting but sometimes hard to get my work done,especially when every drain is clogged .Regional corps usually fails to adequately clear all water courses before rainy season
2010-05-28 17:16:35 | (1 Comments)
The National Works Agency (NWA) in Jamaica is reporting flooding in the Corporate Area and five other parishes due to the heavy rainfall across the island.
As a result, the NWA says several roads in St Catherine, Clarendon St Elizabeth St Thomas and St James are either impassable or open to small vehicles only.
Stephen Shaw, communications manager at the NWA gave a list of some of the affected roads
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