HOUSTON (Reuters) - Bad weather halted some clean-up efforts from the Gulf of Mexico oil spill on Tuesday as high winds and waves from a strengthening storm threatened to hamper plans to capture more of the crude gushing from the largest spill in U.S. history.
The National Hurricane Center said tropical storm Alex would build into the first hurricane of the Atlantic season as it moved over southern Gulf waters.
Ripple effects from Alex produced six-foot (1.8-meter) waves and wind gusts of up to 20 miles per hour and were expected to last a couple of days, said Phil Grigsby of the National Weather Service in New Orleans.
Offshore oil clean-up activity off the Louisiana coast was halted because of severe weather, the U.S. Coast Guard said.
Controlled burns of oil on the ocean, flights spraying dispersant chemicals and booming operations were all stopped, said Coast Guard Petty Officer Kelly Parker. However, BP Plc's oil-capture and relief well drilling continued at the site of the leak.
Grigsby said the weather would also affect clean-up operations on beaches and marshes.
Alex, forecast to strengthen into a hurricane later on Tuesday, was churning northwest across the southwestern Gulf and expected to come ashore near the Texas-Mexico border late Wednesday or early Thursday.
BP spokesman Robert Wine said BP's oil-capture and relief well drilling operations were continuing. "That's all big equipment, and it isn't as affected by the sea state," he said of three rigs and a drillship a mile above the leak.
BP officials have said waves as high as 12 feet (4 metros) would delay plans to hook up a third system to capture much more oil and officials in Florida said high surf would probably hamper clean-up efforts.
BP's market capitalization has shrunk by $100 billion since its Deepwater Horizon drilling rig sank in 5,000 feet (1,525 metros) of water on April 22, two days after an explosion and fire killed 11 workers.
But U.S.-listed shares of BP closed 2.29 percent higher at $27.67 on Tuesday on bargain-hunting. The shares have lost more than half their value since the spill began.
"It's tough to say if the stock has bottomed because the political situation remains so fluid, but on a basis the stock is attractive," said John Brady, senior vice president at MF Global in Chicago.
The stock's weakness since the disaster has also sparked talk of a possible takeover bid.
"The spill is bad, but you need to remember that BP is a global company with a global business, and there's strength elsewhere," Brady said.
The oil spill crisis is in its 71st day with no firm end in sight. The economic and ecological costs to tourism, wildlife, fishing and other industries, already massive, continue to mount for four states along the U.S. Gulf coast.
The lucrative tourism industry in the Gulf could be hard hit for years by a false perception the spill has ruined all the beaches, tourism officials said.
U.S. government officials estimate 35,000 to 60,000 barrels are gushing from the blown-out well each day. BP's containment system can handle up to 28,000 barrels daily. The planned addition would have raised that to 53,000 bpd.
Senior U.S. officials were beating a path to the Gulf region, responding to criticism that President Barack Obama and his administration responded too slowly to the crisis. Tuesday's visitors included Vice President Joe Biden.
A U.S. appeals court set July 8 for oral arguments on the Obama administration's request to stay a ruling that lifted its six-month moratorium on deepwater oil drilling.
A federal judge blocked it at the request of drilling companies, saying the suspension was too broad and arbitrary.
Polls have given Obama low marks for his handling of the disaster, although not as low as those given to BP.
"BP's handling of the spill from a crisis management perspective will go down in history as one of the great examples of how to make a situation worse by bad communications," said Michael Gordon, of New York-based crisis PR firm Group Gordon Strategic Communications.
Mistakes include downplaying the environmental damage, initially blaming others for the disaster and underestimating the amount of oil leaking, analysts say.
As crude oil and dispersants float on the surface of the Gulf, crews are battling to keep it off beaches and away from wildlife breeding grounds.
On Louisiana's Bay Baptiste, winds whipped waves up about a foot high and white caps were visible in the distance as the outer bands of Alex began to move into the region.
Several marshes were only partially boom-protected, with oil coating the bottom part of reeds as crabs covered in crude scurried on nearby marsh islands.
The Atlantic hurricane season runs from June 1 to November 30 and meteorologists predict this year will be very active, suggesting more problems for the oil spill clean-up effort.
In Biloxi, Mississippi, BP spokesman Richard Judy acknowledged problems with clean-up operations after the state's mainland was hit by oil.
"What's keeping us busy in this area is maintaining boom, in some cases putting out new boom, doing pick-up of oiled material on the beaches when it gets there and also going out and working on the coastal islands," Judy said.
"Weather has been a problem. We have to be careful not to keep our crews on beaches if there's lightning nearby."
Additional reporting by Cyntia Barrera Diaz in Mexico City, Ernest Scheyder in Nairn, Louisiana, Leigh Coleman in Ocean Springs, Mississippi, Tom Bergin in London, Deborah Charles in Washington and Joshua Schneyer and Ryan Vlastelica in New York; writing by Jerry Norton; Editing by Chris Wilson