VENICE, La. — As hurricane season approaches, the giant oil spill in the Gulf of Mexico takes weather forecasters into nearly uncharted waters.
The Gulf is a superhighway for hurricanes that form or explode over pools of hot water, then usually move north or west toward the coast. The site of the sunken rig is along the general path of some of the worst storms ever recorded, including Hurricane Camille, which wiped out the Mississippi coast in 1969, and Hurricane Katrina in 2005.
The season officially starts Tuesday, and while scientists seem to agree that the sprawling slick isn't likely to affect the formation of a storm, the real worry is that a hurricane might turn the millions of gallons of floating crude into a crashing black surf.
Some fear a horrific combination of damaging winds and large waves pushing oil deeper into estuaries and wetlands and coating miles of debris-littered coastline in a pungent, sticky mess.
And the worst effects of an oil-soaked storm surge might not be felt for years: If oil is pushed deep into coastal marshes that act as a natural speed bump for storm surges, areas including New Orleans could be more vulnerable to bad storms for a long time.
Experts say there are few, if any, studies on such a scenario.
In this "untreaded water ... it's tough to theorize about what would happen," said Joe Bastardi, chief long-range hurricane forecaster with AccuWeather.com.
The lone precedent, experts agree, is the summer of 1979, when storms hampered efforts to contain a spill from a Mexican rig called Ixtoc 1 that eventually dumped 140 million gallons off the Yucatan Peninsula. Hurricane Henri, a Category 1 storm, damaged a 310-ton steel cap designed to stop the leak that would become the worst peacetime spill in history.
Still, while oil from that spill coated miles of beaches in Texas and Mexico, tropical storms and unseasonable cold fronts that year helped reverse offshore currents earlier than normal and drive oil away from the coast. Storms also helped disperse some of the oil, Bastardi said.
"That's what I think would happen this time," he said. "I'm sure a hurricane would do a great deal of diluting the oil, spreading it out where the concentrations would be much less damaging."
At least 19 million gallons, according to the latest estimates, have leaked from the seabottom 5,000 feet below the surface since the April 20 explosion of BP PLC's Deepwater Horizon rig, which killed 11. Syrupy oil has crept into Louisiana's marshes, coating plants, killing some birds and threatening wetlands.
The threat to the marshes could have implications lasting well beyond this hurricane season. Louisiana already has lost huge swaths of coastal wetlands in recent decades, and the oil is a major threat to the long-term viability of that delicate ecosystem.
If the plants that hold the marshes together were to die at the roots, the base would wash away, leaving deeper water and less of a buffer for hurricanes, said Joseph Suhayda, director of the Louisiana State University Hurricane Center.
"That would increase the amount of surge inland," Suhayda said.
Even without considering hurricanes, there is uncertainty about whether marsh cane and other plants will die to the roots or just above the surface from this oil spill. If the plants' roots survive, they could come back over time. If not, the results could be catastrophic.
"I don't think anybody is going to know precisely. It depends on the quantity of the oil," said David White, a biological sciences professor at Loyola University New Orleans.
There is a chance that a hurricane or tropical storm could offer wetlands a reprieve from the oil, at the expense of areas farther inland. A storm surge of several feet, even if it is carrying oil, would pass over the top of the outer, low-lying marshes and disperse the mess in less toxic amounts, Suhayda said.
But such a storm could also push oil into freshwater marshes where ducks and geese thrive, White said.
Experts are predicting a busy hurricane season with powerful storms. Bastardi predicts seven named storms, five hurricanes and two or three major hurricanes will have an effect on land this year. Colorado State University researchers Philip Klotzbach and William Gray predict a 69 percent chance that at least one major hurricane will make landfall on the U.S. and a 44 percent chance that a major hurricane will hit the Gulf Coast.
On Thursday, the National Oceanic and Atmospheric Administration predicted 14 to 23 tropical storms this year, including up to seven major hurricanes. "This season could be one of the more active on record," agency Administrator Jane Lubchenco said.
Hurricane season begins June 1 and runs through November. Early season storms are uncommon; the busy part of the season is in August through October. Stronger storms typically form during this time, like Katrina did in August of 2005.
A hurricane like Katrina "would be a worst-case scenario" with oil pushed far ashore, said National Wildlife Federation scientist Doug Inkley.
"It would suffocate the vegetation. You'd get oiled birds and other animals," Inkley said. "It's virtually impossible to clean up oil."
It could well be August before the current leak is stanched. After several failed attempts to contain it, BP has been siphoning some of the oil through a mile-long tube, but more continues to escape. BP is drilling another well to relieve pressure from the leak in hopes of a permanent fix, but that could take weeks.
And oil rigs are often evacuated ahead of hurricanes, which would interrupt those containment efforts.
"It wouldn't take a hurricane to create a mess, even a tropical storm could cause problems," said William Hawkins, director the University of Southern Mississippi's Gulf Coast research laboratory.
A hurricane could also push the oil in a new direction.
"I think what worries us most is the hurricane taking oil to areas that probably wouldn't be hit hard otherwise, like the Florida Panhandle and Texas," said Gregory Stone, director of the Coastal Studies Institute at LSU.
Even though the oil has yet to reach Florida, state Attorney General Bill McCollum recently sent a letter to BP asking the company to assure him it would pay up if a tropical storm or hurricane pushes oil ashore, which he believes "will capture the oil in its path and deposit it much further inland."
Bastardi said that in the near term at least, the storms themselves remain the chief threat.
"If a Category 3 hurricane is headed to the Texas Gulf Coast – and this is simply theoretical – I wouldn't be worried as much about damage from the oil, as the damage from the hurricane," Bastardi said.