Unfavorable Weather Worsens the Gulf Oil Spill

About the time disaster response officials realized the magnitude of the Deepwater Horizon Oil Spill, the weather in the Gulf of Mexico was already turning against them. Winds from the west and north, which had held the slick away from the coast, turned and began blowing from the southeast, driving the oil ashore sooner than expected.

The turn of events points up an unhappy fact about ocean oil pollution:  In both the short-term and long-term, human efforts to contain or clean up oil spills can be dwarfed by changes in weather -- winds, storms, surface currents, tides, air and water temperatures and salinity.

(In this trajectory map developed by the National Oceanic and Atmospheric Administration, notice how quickly the spill area spread in response to the change in the winds.)

In the short term, forecasters warned Friday that winds and storm conditions are going to continue to deteriorate over the next few days, driving would-be clean-up vessels into port.  The southerly winds are part of a large-scale circulation around a high pressure system centered over the western Atlantic, the National Weather Service observed, and a "series of surface lows will develop and move through the southern plains and lower Mississippi Valley through the weekend." 

Their outlook was discouraging:

"The combination of these 2 features will result in persistent southeast and then south winds, increasing to between 15 to 25 knots (17 to 29 mph) with higher gusts from tonight through Sunday.  In addition, expect seas to build to a peak of 9-12 feet and have a sea state of very rough during this period."

Forecasters say a cold front slowly moving southeast towards the Gulf will gradually shift winds more directly from the south, and by Sunday night they should subside somewhat. They will begin to shift as the front drops southward into the Gulf waters, and by Tuesday evening they will shift from west, to northwest, to north.  "Winds should be fairly light at 5 to 10 knots (about 6 to 12 mph) from Wednesday through the rest of next week," they predicted.

In the longer-term, air and ocean conditions will continue to dominate the campaign to clean up and disperse the heavy, unrefined crude, the kind of oil that is especially resistant to natural weathering processes, researchers say. 

In a common countermeasure, chemicals known as "dispersants" are sprayed from aircraft or vessels over the oily surface. Chemically, one end of the dispersant molecule attaches to a water molecule, the other to an oil molecule, forming droplets which are broken into even smaller drops by wind and wave action.  The process is intended to break up the concentrated, poisonous surface slick and cause it to form tiny droplets that more easily move down into the water column, diluting its presence and environmental impacts.

The ocean has its own countermeasure that could become more significant in the weeks ahead, depending on the length of time the mile-deep oil well continues to spew into the Gulf and the uncertain future of the winds.  Tropical meteorologist Jeff Masters of Weather Underground points out the potential for the oil to become entrained in a prominent surface current known as the Loop Current which would transport it toward the coasts of Cuba and Florida and out into the Atlantic's Gulf Stream.

"Any oil that does make it into the Loop Current will suffer significant dispersion before it makes landfall in Cuba, Florida, or the Bahamas, and far less oil will foul these shores compared to what the Louisiana coast is experiencing this weekend," Masters wrote.