Clouds, unstable Loop Current making oil spill prediction difficult

By: Dr. Jeff Masters , 8:48 PM GMT on May 18, 2010

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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

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Quoting hurricane23:
Morning,

The GFS ensembles, the operational ECMWF and ECMWF ensembles all show this developing to some degree in the sw caribbean.I guess it's a plausible scenario given the warm ssts down there and the weak spot in the westerlies south of the zonal jet.


Welcome aboard.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting P451:
Wave heading towards Africa:



Laila:



Tropical waves form over the highlands of Ethiopia in the AEJ.

Two totally different species there.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Morning,

The GFS ensembles, the operational ECMWF and ECMWF ensembles all show this developing to some degree in the sw caribbean. I guess it's a plausible scenario given the warm ssts down there and the weak spot in the westerlies south of the zonal jet.
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Good morning everyone.. good afternoon Aussie!
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ITCZ is alot more concentrated and stronger than 2005 at 50W from May 1-18.

The ITCZ at 50W is 5N in both years



Member Since: July 24, 2005 Posts: 407 Comments: 19076
761. eddye
dang look at all the rain coming to south florida
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759. eddye
wow the new gfs takes a system to south florida
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good morning all
here is latest GFS run this am

Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting aspectre:
For the sake of simplicity let us assume that the crude oil has 5/6ths the density of seawater.
That means that 5gallons of seawater weighs the same as 6gallons of crude oil, 6litres of crude oil weighs the same as 5litres of seawater, etc.

Pure water has a weight of 16.387064grams per cubic inch, so a cubic inch puts 16.387064grams of weight on a square inches
A foot of one-inch cubes of water stacked one upon another puts 196.644768grams of weight on a square inch.
There are 453.59237 grams per pound, so a foot-high column of water puts 196.644768/453.59237 pounds of pressure on a square inch.
ie Each&every increase of one foot in the height of a water column produces 0.43352757 more pounds per square inch (psi) of pressure on the base of the column.

So 32feet of pure water puts ~13.9psi of pressure on the bottom. And having 1000feet of water above produces ~433.5psi of pressure.

And if the ocean were pure water, the 1000foot pipe of crude oil would produce 5/6ths of ~433.5psi or ~361.273psi of pressure at the sea surface.
BUT that 1000foot column is keeping a 5000foot column of oil under the surface.
Remove the 1000foot column at the surface, and the 5000foot column produces ~361.3psi of upward pressure drawing oil from the bottom of the pipe.

HOWEVER we started off talking about seawater, then switched to pure water for the calculations. Seawater is ~1.025 times the density of pure water.
So 32feet of seawater produces a pressure of ~14.2psi (approximately the pressure of air at sea level). And a 1000foot column of crude oil produces ~370psi psi of pressure.
ie Remove the 1000foot column of seawater at the surface, and the 5000foot column of crude produces ~370psi of upward pressure at the ocean surface drawing oil from the bottom of the pipe.

The (excess)pressure at the broken pipe on the seabed is produced by the weight of the rock below the seabed upon the oil at the bottom of the well.
If we assume (for the sake of simplicity) that the rock above the oil deposit has the same density as the average density of the crust, then a given height of rock produces ~2.75 times the pressure as the same height of pure water.
So 5000feet of rock produces ~2.75times361.273psi of (excess)pressure or ~1000psi at the seabed.

The well was bored to 13,350feet below the seabed, so the pressure at pipe intake produces
13,350divided-by5000times1000psi at the seabed, or 2,670psi.

The articles mentioning tens of thousands of pounds of pressure are talking about the total pressure at the bottom.
The effective pressure within a pipe is equal to the difference between the weight of a column of crude oil and the weight of an equivalent column of surrounding rock and/or seawater

This is quite complex, and I am not sure what you are trying to conclude.
Is it that the oil flowing out of the pipe has to be at a pressure greater than 2670 psi? At the level of the sea bed?
Member Since: October 24, 2005 Posts: 0 Comments: 24025
756. IKE
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Continuing a conversation with pottery

For sake of simplicity let's assume that crude oil has 5/6ths the density of seawater.
That means that 5gallons of seawater weighs the same as 6gallons of crude oil,
6litres of crude oil weighs the same as 5litres of seawater, etc.

So a 6foot column of crude oil will produce the same pressure on the bottom as a 5foot column of seawater. ie Assumming that the crude oil in one vertical pipe and the seawater in another vertical pipe meet in a level connection between the otherwise sealed bottoms of those two pipes, 5feet of seawater in one pipe will support 6feet of crude oil in the other pipe, and thus the top of the crude oil will be 1foot higher than the top of the seawater.

Pure water has a weight of 16.387064grams per cubic inch, so a cubic inch puts 16.387064grams of weight on the square inch at its bottom.
A foot of one-inch cubes of water stacked one upon another puts 196.644768grams of weight on a square inch. (12inches per foot for the metricly educated)
There are 453.59237 grams per pound, so a foot-high column of water puts 196.644768divided-by453.59237 pounds of pressure on a square inch.
ie Each&every increase of one foot in the height of a water column produces 0.43352757 more pounds per square inch (psi) of pressure on the base of the column.

So 32feet of pure water puts ~13.9psi of pressure on the bottom. And having 1000feet of water above produces ~433.5psi of pressure.

And if the ocean were pure water, a 1000foot vertical pipe of crude oil with its bottom meeting the sea surface would produce 5/6ths of ~433.5psi or ~361.273psi of pressure upon the sea surface.
BUT that 1000foot column is keeping a 5000foot column of oil under the surface.
Remove that 1000foot column above the surface, and the 5000foot column produces ~361.3psi of upward pressure lifting oil from the bottom of the pipe.

HOWEVER we started off talking about seawater, then switched to pure water for the calculations. Seawater is ~1.025 times the density of pure water.
So 32feet of seawater produces a pressure of ~14.2psi (approximately the pressure of air at sea level). And a 1000foot column of crude oil produces ~370psi psi of pressure.
ie Remove the 1000foot column of crude pressing down upon the surface, and the 5000foot column of crude beneath produces ~370psi of upward pressure at the ocean surface drawing oil from the bottom of the pipe.

The (excess)pressure at the broken pipe on the seabed is produced by the weight of the rock below the seabed upon the oil at the bottom of the well.
If we assume that the rock above the oil deposit has the same density as the average density of the crust, then a given height of rock produces ~2.75 times the pressure as the same height of pure water.
So 5000feet of rock produces ~2.75times361.273psi of (excess)pressure or ~1000psi of (excess)pressure at the seabed.

The well was bored to 13,350feet below the seabed, so the pressure at pipe intake produces 13,350divided-by5000times1000psi of (excess)pressure at the seabed, or 2,670psi of (excess)pressure.

The articles mentioning tens of thousands of pounds of pressure are talking about the total pressure at the bottom.
The effective*pressure within a pipe is equal to the difference between the pressure produced by the weight of a column of crude oil and the pressure produced by the weight of an equivalent column of surrounding rock and/or seawater.

* ie The (excess)pressure which produces upward movement of the contents within the pipe, and the equivalent to suction at the pipe's intake at the bottom.
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1493 519
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Notice the SW Caribbean
24 H



48 H



72 H

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What I am a little suspisious about the NOAA thing is that no other source has this and the official one NOAA still has May 20 in the agenda.
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Quoting shoreacres:
I see the mention of NOAA's forecast delay came from Ken Kaye over at the Sun Sentinel. Ken has weather-blogged there for some time and has been a reporter - a good reporter - for years longer. He also has blogged here at WU for at least a couple of years, I'd say.

If he reports it, I'd give it credence. And he does tend to post things others just don't seem to be interested in. If you're interested in his sources you can leave a comment at the Sun-Sentinel or WU mail him under the name StormKen.


oh I see.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I see the mention of NOAA's forecast delay came from Ken Kaye over at the Sun Sentinel. Ken has weather-blogged there for some time and has been a reporter - a good reporter - for years longer. He also has blogged here at WU for at least a couple of years, I'd say.

If he reports it, I'd give it credence. And he does tend to post things others just don't seem to be interested in. If you're interested in his sources you can leave a comment at the Sun-Sentinel or WU mail him under the name StormKen.
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Quoting pottery:

Yeah , that would work!
And "Certified Lurker".


funny, hard to believe that much time has passed
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Quoting aquak9:
Degrees to anyone who can show that they have read , say 1000 posts from the main page here.

how about five years of obsession? :)

Yeah , that would work!
And "Certified Lurker".
Member Since: October 24, 2005 Posts: 0 Comments: 24025
748. IKE
I don't see any logical reason for NOAA to delay releasing the information.

I would believe it being delayed if it was on the NOAA site.
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Quoting Weather456:


I have to question the reliability of that article. Why was this posted on that site and not any other news article? Why was this not even posted by the horse's mouth?
No idea, we'll see tomorrow. Have a great day!
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Thanks StormW
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Quoting Tropicsweatherpr:
Here is the articule that was posted last night about the delay of NOAA's May forecast.

Link
Yeah, I posted it.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Tropicsweatherpr:
Here is the articule that was posted last night about the delay of NOAA's May forecast.

Link


I have to question the reliability of that article. Why was this posted on that site and not any other news website? Why was this not even posted by the horse's mouth?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
ECMWF 00z 144 hours:



NOGAPS 06z 144 hours:



CMC 00z 144 hours:



Models in a consensus that things will unfold rapidly at 144 hours. I have to go, I'll be checking in later today, have a great day!
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Here is the articule that was posted last night about the delay of NOAA's May forecast.

Link
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741. IKE
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Degrees to anyone who can show that they have read , say 1000 posts from the main page here.

how about five years of obsession? :)
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Quoting Weather456:
NOAA still has it on their list of agendas.
Interesting. Guess we'll find out what happens, tomorrow.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Wow models are going insane with that subtropical system. Here is the GFS 06z 144 Hours:

Notice:

*1006 MB low in the SW Caribbean
*1007 MB low north of HispaƱola
*1001 MB low drifting northward (this is the hybrid system that is being forecasted by the NOGAPS, ECMWF, and obviously the GFS



Looks like now we will have 3 chances at Alex.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting pottery:
The only problem with all these featured bloggers on here, is that it takes so long to read them all.
But what a fantastic amount of Tropical Weather information, in one place.
Thank you Dr.M, 456, Storm, and the WU Crew.
'nuff Respect!

Further to that, I think that Met. Schools should consider giving Degrees to anyone who can show that they have read , say 1000 posts from the main page here.
You would have to be a dam fool not to learn something......
Member Since: October 24, 2005 Posts: 0 Comments: 24025
Quoting cg2916:


What day?


Thursday May 20
Member Since: July 24, 2005 Posts: 407 Comments: 19076
735. IKE
Quoting severstorm:

Thats great. We were to get some good rain monday and tuesday but it really didn't pan out. I think i got .009 of an inch. Oh well next time.


I got 1.36 yesterday.

Sunny now and 65.5 outside.
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Quoting Weather456:
NOAA still has it on their list of agendas.


What day?
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NOAA still has it on their list of agendas.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
The only problem with all these featured bloggers on here, is that it takes so long to read them all.
But what a fantastic amount of Tropical Weather information, in one place.
Thank you Dr.M, 456, Storm, and the WU Crew.
'nuff Respect!
Member Since: October 24, 2005 Posts: 0 Comments: 24025
Good morning from a very wet Germany (flooding is heading to us the next days)

WSJ Blogs
May 18, 2010, 11:03 AM ET.Central Europe Battles Massive Floods

Seven people are reported dead and thousands have been evacuated from their homes and workplaces across central Europe as swollen rivers burst their banks after several days of heavy rain.

More: http://blogs.wsj.com/new-europe/2010/05/18/central-europe-battles-massive-floods/
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Quoting Tropicsweatherpr:
Does anyone know any news about NOAA delaying their May forecast that is supposed to be released tommorow? I ask because someone posted last night an articule from a newspaper saying that but no other source mentioned anything.


I have not seen anything on their website.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Tropicsweatherpr:
Does anyone know any news about NOAA delaying their May forecast that is supposed to be released tommorow? I ask because someone posted last night an articule from a newspaper saying that but no other source mentioned anything.


Dunno. It should come out Sunday at the latest.
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Good morning!
Post 690, xcool.
Looks like a sudden consolidation of the area?
What's up with that?
Member Since: October 24, 2005 Posts: 0 Comments: 24025
Does anyone know any news about NOAA delaying their May forecast that is supposed to be released tommorow? I ask because someone posted last night an articule from a newspaper saying that but no other source mentioned anything.
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Quoting xcool:



new new




ngp new


Top one looks like Chantal from '07.
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Quoting IKE:


I had over an inch of rain yesterday afternoon. Gotta check my gauge for the exact total.

Thats great. We were to get some good rain monday and tuesday but it really didn't pan out. I think i got .009 of an inch. Oh well next time.
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Hey, guys!

Been a while since I've looked at the blobs, how are they doing? I need to know now because I have crow waiting.
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721. IKE
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720. IKE
Quoting severstorm:
Good Morning, StormW, Ike, 456 and all. looking like hot dry weather for w c fl rest of the week.


I had over an inch of rain yesterday afternoon. Gotta check my gauge for the exact total.
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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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