BP, for now, appears to have dodged Hurricane Alex. If current forecasts hold, the eye of the storm will miss the site of the Deepwater Horizon blowout by about 600 miles, and the Mexican coast south of Brownsville, Texas, will get the worst of the storm.
But Alex still qualifies as a warning shot. What happens when a hurricane or tropical storm passes over the site of the worst oil accident in America's history?
"This is a first, to see a spill of this size in tropical waters," said Chris Vaccaro of NOAA, the National Oceanic and Atmospheric Administration, which forecasts weather and hurricanes. "So nobody has a lot of experience."
But scientists say some of the effects can be predicted -- some bad, some of them not so bad. A storm could make a mess of the cleanup effort, but it could also speed the effort along.
Some major factors, with the potentially-complicating ones first:
Storm Surge: This is the bulge of water that a storm, in effect, pushes out ahead of it as it moves over open water. In the case of a major storm -- Katrina, for instance, in 2005 -- it can raise the water level by as much as 15 feet. Alex is a weaker storm, with a likely storm surge of 3-5 feet, but much of the land along the Gulf Coast is at or even below sea level.
Now imagine all that floodwater ... mixed with oil.
Hurricane Winds: Tropical cyclones in the northern hemisphere turn counter-clockwise. "In very general terms," says NOAA, "A hurricane passing to the west of the oil slick could drive oil to the coast. A hurricane passing to the east of the slick could drive the oil away from the coast."
Those are generalities, though, says the agency. The particulars of a storm can be very different.
Choppy Seas: Two decades after the Exxon Valdez, the technology of cleanup has not changed much. Flotation booms, either to corral oil or protect a coastline, continue to be a first line of defense.
They work, very simply, because most oil floats -- and won't go under a floating barrier. But if the seas are churned up by a major storm, a flotation boom may not be very effective. More work for already-stressed-out cleanup workers after the storm is over.
"It may change significantly where the oil is located," said Tony Barnston, lead forecaster at the International Research Institute for Climate and Society at Columbia University in Palisades, New York. "It would definitely spread it around both vertically and horizontally. It would break it up, it would mix things up."
A storm passing over the spill zone could spread the oil over a larger area, but it could also have the benefit of dispersing the oil.
Dispersant Effect: High winds and heavy rains can pummel everything in their path -- including an oil slick. Meteorologists say the oil would be broken into smaller globs, which could actually speed the process of chemical breakdown.
In the subtropical climate of the Gulf, the oil is slowly consumed by microorganisms. The hot sun also helps break it down into less volatile components.