NEW YORK (Reuters) - BP’s oil spill could make for one of the highest-stakes U.S. Gulf hurricane seasons on record.

Todd Farrar with SCAT (Shoreline Cleanup Assessment Team), MST 3 Nicole Tainatongo with the U.S. Coast Guard and Tyler Hardy with MDEQ (Mississippi Department of Environmental Quality) walk at the beach looking for signs of oil in Pass Christian, Mississippi May 12, 2010. REUTERS/Sean Gardner

Storms may scuttle clean-up efforts, force containment vessels to retreat, or propel spilled crude and tar balls over vast expanses of sea and beach, scientists said.

Meteorologists say that climate conditions are ripe for an unusually destructive hurricane season, the storm-prone period that runs from June 1 to the end of November in the Gulf. Oceanographers say that could hurt the clean-up.

“If a storm comes into this situation it could vastly complicate everything,” said Florida State University oceanography professor Ian MacDonald.

“All efforts on the shoreline and at sea, the booms and structures and rigs involved in clean-up and containment, could stop working.”

As thousands of spill responders gird for a clean-up that could last for months or years after the leaking well is capped, weather and ocean currents are emerging as major unknowns, raising anxiety levels, economic and environmental stakes in the Gulf as storm season nears.

Compounding the uncertainty is how little research has been done on how storms affect oil spills. Some believe storm surges may help disperse the oil off shore or break down the slick. Other research suggests the oil slick itself could keep storms from gathering strength.

Recent Atlantic Basin readings showed water temperatures up to 0.8 degrees Celsius above normal, and near a record high for the season. El Nino, which creates wind shear that can prevent Gulf hurricanes from forming, has recently subsided. The factors could spur major storms in the Gulf this year.

“It only takes one storm to wreak havoc,” said Chris Shabbot, a meteorologist at Sempra in Connecticut. “The consensus forecast is for above average storm activity as the El Nino (event) decays and the Atlantic is as warm or warmer than 2005.”

Colorado State University’s renowned team of forecasters is calling for an above-average hurricane season that may bring 15 named storms this year, eight of hurricane strength.

Accuweather’s Joe Bastardi also fears a destructive season.

“I hate to say it since the oil spill is already affecting people, but I think this hurricane season is going to be big,” he said in an interview.

The next official hurricane season outlook from the government’s National Oceanic and Atmospheric Administration is due on May 20.

STORMS AND CURRENTS

Miles and miles of booms have been placed offshore along the Gulf Coast to help stop the slick from making landfall.

Amid the menacing forecasts, oceanographers and spill-responders are considering how storms and deep ocean currents would affect the movement of spilled oil, which authorities say could soon hit land in Louisiana, Mississippi, Alabama or Florida.

The U.S. coast of the Gulf of Mexico spans some 1,680 miles. The spill, gushing an estimated 5,000 barrels a day from a subsea oil well 50 miles south of Louisiana, has formed a thin oil slick that covered more than 1,200 square miles in late April, according to Louisiana State University researchers. The slick has been harder to define this month, and may be shrinking, LSU professor Nan Walker said.

Lurking under the sea surface, viscous tar balls are forming, facilitated by wave activity, as the heavier hydrocarbon molecules gradually sink toward the sea-floor, a process that can take months, scientists said.

Experts are having trouble modeling how the oil will react in water since BP hasn’t disclosed exactly what kind of crude is spilling. Lighter oil evaporates quicker and is more easily dispersed by chemicals. Heavier crude can be more damaging to marine or bird life, but it could sink faster or be easier to contain.

As many as 520 vessels are already responding to the spill throughout the Gulf, according to U.S. authorities. Efforts to stop the spill involve drilling relief wells from a seaborne rig, which BP says could take three months. The company is also trying to cap the leak with a metal funnel on the sea-floor, to gather oil into a giant hose connected to a storage ship above.

Both of those efforts could be disrupted by tropical storms, which can force evacuation of oil and gas rigs throughout the Gulf.

Peter Niiler, an oceanographer at the Scripps Institution in San Diego, has researched how even winds caused by a low pressure cycle can displace floating scientific buoys from waters near Florida to Texas in less than a week.

“Anything on the ocean surface, including oil, can move very fast and just about anywhere that wind or currents push it,” Niiler said.

The oil slick might even reach waters and shores abroad, scientists and foreign authorities warned this week.

Mexican officials say if the spill persists into the fall it could reach Mexican beaches along the country’s Gulf Coast, the site of famed tourist destinations like Cancun.

Some of the spilled crude should make its way into the LOOP current, a deep ocean stream that transfers heat from the tropics to higher latitudes and becomes the Gulf Stream.

“If you look at it, the LOOP current could lead that oil right to Havana, Cuba,” said Florida State’s MacDonald.

After sweeping near Havana, the LOOP current continues toward the Florida Keys and the Gulf Stream heads up the U.S. Eastern Seaboard.

Some researchers said a wider dispersion of the spill may be good, and storms could help that process along. Researchers at NOAA, in a report last week, said the oil slick may also help to impede storm formation by preventing heat transfer from sea to air.

“There are two important issues here: the effect of hurricanes on the spill, and the effect of the spill on hurricanes,” said Doron Nof, professor of oceanography at Florida State University.

“I think what a hurricane would do is break up the oil spill, making it even harder to clean up,” he said.