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Long range oil spill forecast

By: Dr. Jeff Masters, 3:02 PM GMT on June 04, 2010

Onshore winds out of the south, southwest, or west are expected to blow over the northern Gulf of Mexico over through Tuesday, resulting in a continued threat of landfalling oil to Alabama, Mississippi, and the Florida Panhandle, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The latest ocean current forecasts from the NOAA HYCOM model show that these winds will generate a 0.5 mph current flowing from west to east along the Florida Panhandle coast Sunday through Tuesday. If this current develops as predicted, it will be capable of bringing light amounts of oil as far east as Panama City, Florida, by Wednesday. Long range surface wind forecasts from the GFS model for the period 8 - 14 days from now predict a return to a southeasterly wind regime, which would bring the oil back over Louisiana by mid-June. If you spot oil, send in your report to http://www.gulfcoastspill.com/, whose mission is to help the Gulf Coast recovery by creating a daily record of the oil spill.

Long range oil spill outlook
The National Center for Atmospheric Research (NCAR) issued a press release yesterday showing 4-month model runs (Figure 1) of where the Deepwater Horizon oil spill might go. The model runs show that given typical ocean currents in the Gulf of Mexico, we can expect the oil to eventually affect most of the Florida Panhandle, Keys, and Florida East Coast, as well as coastal areas of South Carolina and North Carolina. Very little oil makes it to the West Florida "Forbidden Zone", where offshore-moving surface currents dominate. The oil may eventually affect three foreign countries: Mexico along the northern tip of the Yucatan Peninsula, Cuba near Havana, and the Bahamas in the Bimini Islands and along the western side of Grand Bahama Island. Once oil does get into the Loop Current, it will probably reach the coasts of France, Spain, and Portugal in about a year. The oil will be too dilute by then to be noticeable, though.

The present ocean current configuration in the Gulf features a newly formed Loop Current Eddy (dubbed "Franklin"), which will tend to capture the majority of oil that flows southwards from the Deepwater Horizon spill site. A plot of drifting buoys (drifters) launched into the Gulf May 19 - 24 (Figure 2) reveals how this clockwise-rotating eddy has been capturing southward-moving surface water. Eddy Franklin will move slowly west-southwest at 2 - 3 mph in the coming weeks. By August or September, the eddy will have moved far enough west that the Loop Current will be able to push northwards towards the spill location again, increasing the chances of oil getting into the Loop Current and being advected through the Florida Straits and up the U.S. Southeast Coast. Between now and mid-August, I doubt that a significant amount of oil will get into the Loop Current, unless a hurricane or tropical storm goes through the Gulf of Mexico. I put the odds of this happening by mid-August at 50%. The odds of a named storm in the Gulf of Mexico will increase sharply after mid-August, when the peak portion of hurricane season arrives. Past history shows a 95% chance of getting two or more named storms in the Gulf of Mexico during hurricane seasons with above-normal activity.

Figure 1. Animation from the National Center for Atmospheric Research (NCAR) showing one scenario of how oil released at the location of the Deepwater Horizon disaster on April 20 in the Gulf of Mexico may move in the upper 65 feet of the ocean.

Figure 2. During the R/V Bellows 19-24 May 2010 Cruise into the Loop Current, drifters were dropped on the eastern edge of the Loop Current. These drifters have all been caught in Loop Current Eddy "Franklin", and are orbiting the central Gulf of Mexico in clockwise loops. Additional drifters deployed by the Coast Guard over the past few weeks (orange colors) are also shown. The colored balloons show the starting location of the drifters. Image credit: University of South Florida.

Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil 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
Oil trajectory forecasts from NOAA
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Figure 2. Visible satellite image of Tropical Cyclone Phet on Friday, June 4, 2010.

Tropical Cyclone Phet unleashes heavy rains on Oman
Tropical Cyclone Phet hit the northern tip of Oman yesterday as a Category 2 storm, bringing torrential rains and killing at least two people. Masirah, Oman recorded sustained winds of 74 mph yesterday, and Sur, Oman on the northeast coast has received 3.25 inches of rain so far. Phet was the 2nd strongest tropical cyclone ever recorded in the Arabian Sea, when it peaked at Category 4 strength with 145 mph. Only Category 5 Cyclone Gonu of 2007, which devastated Oman, was stronger. Phet has emerged from the coast of Oman this morning, but is likely to weaken over the next day due to increased wind shear. Phet should hit Pakistan as a tropical storm on Saturday, bringing heavy rain and serious flooding.

Next update
I'll probably have one update over the weekend. The tropical Atlantic is quiet right now, with no models predicting tropical cyclone development over the next seven days.

Jeff Masters

Air and Water Pollution

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.