Clouds, unstable Loop Current making oil spill prediction difficult
It's cloudy over the Gulf of Mexico today, so it is difficult to tell how far into the Loop Current the Deepwater Horizon oil has penetrated using visible satellite imagery. Satellite imagery yesterday from NASA's MODIS instrument confirmed that a tongue of oil moved southeast from the Deepwater Horizon oil spill and entered the Gulf of Mexico's Loop Current. However, Synthetic Aperture Radar imagery from the European Envisat satellite posted at ROFFS Ocean Forecasting Service shows that while some of the tongue of oil that entered the Loop Current appears to be circulating southwards towards the Florida Keys, perhaps 80% of the oil in this tongue is caught in a counter-clockwise circulating eddy along the north side of the Loop Current. This oil may eventually circulate around and enter the Loop Current, but not for at least three days.
Figure 1. Oil spill forecast for this Thursday night as simulated by the 6pm EDT Monday May 17 runs of the Navy Gulf of Mexico HYCOM nowcast/forecast system and the Global HYCOM + NCODA Analysis from the HYCOM Consortium. See the University of South Florida Ocean Circulation Group website for more information. There are considerable differences between the two models, due in part to the fact that they have much different depictions of the sea surface temperatures (SSTs) and ocean currents at the beginning of their runs. The warm Loop Current is visible as the red colors of the SST field that form a heart-shaped area in the Gulf.
How long will it be until oil reaches the Keys?
Once oil gets into the Loop Current, the 1 - 2 mph speed of the current should allow the oil to travel the 500 miles to the Florida Keys in 5 - 10 days. Portions of the Loop Current flow at speed up to 4 mph, so the fastest transport could be 4 - 5 days.
How much oil has made it into the Loop Current?
According to the latest trajectory forecasts from NOAA, the tongue of oil flowing southwards has, at most, "light" concentrations. The oil will grow more dilute as it travels the 500 miles to the Florida Keys, and most of the oil appears to be caught in a smaller counter-clockwise rotating eddy on the north side of the Loop Current. My present expectation is that the oil entering the Loop Current this week will cause only minor problems in the Keys next week. However, there is a lot of uncertainty regarding how much oil will get to the Keys, and we cannot rule out the possibility of an ecological disaster in the fragile Keys ecosystem.
How is the Loop Current changing?
The Loop Current has been highly chaotic and unstable over the past week, making it difficult to predict how the ocean currents near the spill will behave. According to ROFFS Ocean Fishing Service, which has done a tremendous job tracking the spill, the Loop Current surged 7 - 10 miles northward Sunday and Monday. The Loop Current has gotten more contorted since Friday, and may be ready to cut off into a clockwise-rotating Loop Current Eddy. This process occurs every 6 - 11 months, with the clockwise-rotating ring of water slowly drifting west-southwest towards Texas. The last eddy broke off ten months ago, so the Loop Current is due to shed another eddy in the next few months. The latest 1-month forecast from the U.S. Navy does not predict an eddy forming, but these forecasts are not very reliable. If a Loop Current Eddy does break off, oil getting entrained into it might orbit the center of the Gulf of Mexico for many months inside the eddy. However, this eddy will probably reattach and detach from the main Loop Current flow for at least a month following when it breaks off, so oil will continue to flow through the Keys during this initial month.
When will the flow of oil into the Loop Current shut off?
Winds over the oil spill location are expected to be light and onshore at 5 - 10 knots through Saturday. This means that the chaotic contortions of the Loop Current will primarily control how much oil gets into it, making it difficult to predict when the flow will shut off. The long range (and thus unreliable) forecast for next week from the GFS model calls for a continuation of light winds over the eastern Gulf of Mexico. Thus, the flow of oil into the Loop Current could occur intermittently for several weeks.
Who besides the Keys are at risk next week from the Loop Current oil?
As I discussed in an earlier post, the coast of Southwest Florida from Tampa Bay to the Everglades is a "Forbidden Zone" for surface-based transport of ocean water to the coast, and is probably not at risk from this week's Loop Current oil. The northwest coast of Cuba east of Havana and the coast of Southeast Florida from the Keys to West Palm Beach are at the most risk. The western shores of the western-most Bahama Islands and the U.S. coast north of West Palm Beach northwards to Cape Hatteras are at slight risk. It would likely take ocean eddies 2 - 9 weeks to transport the oil to these locations, and the oil would probably be so dilute that ecosystem damage would probably be minor, at most. At this point, I see no reason for cancellation of vacation plans to any of the beach areas that may potentially be affected by the oil.
What is happening to the plumes of oil at depth?
Two research missions over the past week have detected substantial plumes of oil at depth, moving to the southwest. The deepest of the these plumes, near the site of the blowout at 5,000 feet depth, is in a region of slow ocean currents and has not moved much. At depths closer to the surface, the currents get stronger, and oil within a few hundred feet of the surface--if there is any--could potentially have been dragged into the Loop Current. At this point, we don't have a very good picture of how much oil is at depth and where it might be headed.
Oil spill resources
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
HYCOM ocean current forecasts from LSU
The tropics
For those of you interested in a detailed look at the early season tropical weather outlook, consult the excellent wunderblogs of StormW and Weather456, who are now featured bloggers for the coming hurricane season. We have some models predicting a possible subtropical storm off the U.S. East coast next week, but this does not appear to be a significant concern for land areas at this time. More concerning is the possibility that an area of disturbed weather will develop across the Western Caribbean late next week. While wind shear will likely keep anything in the Western Caribbean from developing, several models are predicting that this disturbance may bring major flooding rains to earthquake-ravaged Haiti late next week.
I'll be back with a new post Wednesday afternoon.
Jeff Masters
Reader Comments
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My numbers are 18-10-6. My Atlantic hurricane outlook for this year can be found on my blog.
A system in the Gulf is developing an eye-like feature but is under high shear and is devoid of vorticity.
Amarillo, Vertically Integrated Liquid Range 124 NMI
Sure
....which is exactly why that isn't an eye-like feature.
40% makes me laugh.....you really going with the IRI on this one?
Amarillo, Storm Relative Mean Radial Velocity 1.45 Degree Elevation Range 124 NMI
Posted May 12th..
El Nino event of 2009/10 ends
the IRI had 35% and no I'm not going with them. You'll see why.
-0.2C
Good, because this is beyond funny.
They consider that "low" probability for a La Nina. The atmosphere is already screaming La Nina with the SOI skyrocketing positive in the 90-day values and Atmospheric Angular Momentum going negative, and the ocean is following very rapidly. We're practically skipping neutral right now.
ONI defines La Nina as a seasonal anomaly less than -0.5. And your correct, there are signs of an approaching La Nina but its not that simple.
Seen this?
Think-Tank Says Trained Chimp Can Predict Hurricanes Better Than NOAA -- And Puts it to the Test
http://www.prnewswire.com/news-releases/think-tank-says-trained-chimp-can-predict-hurricanes-better -than-noaa----and-puts-it-to-the-test-94145264.html
lol
lol lol
Yeah, but you can see it everywhere. The 90-day SOI is skyrocketing positive and Atmospheric Angular Momentum is going negative, plus the longwave pattern over North America has been very La Nina-like the last several weeks with the mean trough slamming into the west. The wild swings in the east are also a product of seasonal variations coupled with the rapid reversal in the Pacific. With the easterlies taking over in the Pacific the MJO is becoming better behaved and oriented toward the Atlantic and Indian Oceans instead of the Pacific, which it is now skipping over and that pattern will likely continue through the hurricane season. All that cold subsurface water in the Pacific is just waiting to upwell too.
Dynamic model forecasts like the Euro which have been dead on with this all winter long are taking us to a borderline weak-moderate Nina during the summer months, which makes a lot more sense to me than the US-based forecasts.
GFS is usually a little crazy with the MJO amplitude, has been for years.
I recommend the ensemble...
Hopefully the 27 km resolution improvement next month will help with the MJO forecasts...probably will be the most obvious benefit.
If it's another "forecast" like last year, which was 9-14....I'll scream. Someone did the calculations and that's like forecasting a high of 70-87 degrees in New York city in August. How much more vague can you get.
lol lol
Umm, is that code for WUbloggers?
:P
A press conference, which was to be held on Thursday morning at NOAA’s Hurricane Research Division on Virginia Key in Miami, has been delayed.
Why? Susan Buchanan, NOAA spokeswoman in Washington, D.C., couldn’t say. It was a decision made far up the ladder for reasons unknown.
Some possibilities:
-- NOAA doesn't want to hold the press conference in South Florida, when the region is preoccupied with the threat of the oil spill coming this way.
-- NOAA Administrator Jane Lubchenco got tied up and couldn't make it on Thursday.
-- NOAA is waiting for more data before finalizing its forecast.
I'm sure the agency will tell us the real reason in days upcoming.
Meanwhile, Buchanan said the outlook likely will be released next week, which will be cutting it close, considering the season starts on June 1.
There also is a chance that the outlook will be issued in Washington, she said.
Hurricane season starts in less than a month. Sign up for this year's Hurricane Alert Newsletter at SunSentinel.com/joinus
Are you frikin' kidding me??????
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