MOBILE, Alabama - A weakened Tropical Storm Ida drenched the U.S. Gulf Coast and oil installations on Monday, shutting down nearly 30 percent of Gulf energy production.

Ida was expected to strike the coast near Mobile, Alabama, early on Tuesday. At one time a Category 2 hurricane, Ida's threat eased as winds dropped to 70 miles per hour (112 km per hour). They were expected to decrease further as the storm approached landfall.

A U.S. Coast Guard helicopter plucked two workers from a storm-damaged oil rig about 80 miles south of New Orleans. Ida is blamed for 124 flood and mudslide deaths in El Salvador.

The Coast Guard closed the Port of Mobile, halting traffic on Mobile Bay, and authorities closed schools and government offices in coastal counties in Alabama and Florida, telling residents of flood-prone areas and mobile homes to evacuate.

Ida, which was downgraded to a tropical storm earlier on Monday, posed the first real storm threat of the 2009 Atlantic hurricane season to Gulf of Mexico oil and natural gas production, and forced some companies to shut down off-shore platforms and evacuate personnel.

The U.S. Minerals Management Service said that Ida had shut down 29.6 percent of Gulf oil production and 27.5 percent of gas output.

Energy markets have been hypersensitive to Gulf cyclones since the devastating 2004 and 2005 seasons, when storms like Katrina disrupted U.S. output and sent pump prices soaring.

Although Ida's winds were still near hurricane force, most offshore oil rigs in the Gulf won't see winds over 50 mph, said Jim Rouiller, senior energy meteorologist at private forecaster Planalytics Inc.

I don't think there will be any damage (to oil rigs) and I think that by tomorrow it will be normal operations across the production region, Rouiller said.

OIL PRICES RISE

Oil rose more than $2 to near $80 a barrel on Monday on fears of supply disruptions.

The Louisiana Offshore Oil Port, the only U.S. terminal capable of handling the largest tankers, stopped unloading ships due to stormy seas. And the Independence Hub, a major offshore natural gas processing facility, also was closed.

A quarter of U.S. oil and 15 percent of its natural gas are produced from fields in the Gulf, and the coast is home to 40 percent of the nation's refining capacity.

At 4 p.m. EST (2100 GMT), the storm was about 60 miles southeast of the mouth of the Mississippi River and was headed north at about 18 mph, the U.S. National Hurricane Center said.

Hurricane warnings for the U.S. Gulf Coast were discontinued. A tropical storm warning was in effect from Grand Isle, Louisiana, eastward to Aucilla River, Florida, meaning that tropical storm conditions are expected within 24 hours.

The warning area included New Orleans, which is still recovering from the devastation of Katrina.

In Mobile, Alabama, on the U.S. Gulf Coast, Governor Bob Riley warned residents to be on guard, and declared a state of emergency for the state.

At this point, we don't know how substantial this damage could be, Riley said. We hope it continues to dissipate.

Local authorities reported flooding from waves and storm surge at the developed west end of Dauphin Island, the barrier island off Mobile, which was heavy damaged by Katrina in 2005.

Schools, beaches and parks closed in the Florida Panhandle, the same area hit in August by Tropical Storm Claudette, the only other cyclone to make a U.S. landfall during the 2009 Atlantic season, one of the least active in a decade.

In El Salvador, rivers burst their banks and hillsides collapsed under rains triggered by Ida, cutting off parts of the mountainous interior from the rest of the nation.

The bulk of the Central American country's coffee is grown in areas far from the worst affects of the flooding but the national coffee association had no estimate of damage.

(Additional reporting by Jose Cortazar and Michael O'Boyle in Cancun, Nelson Renteria in San Salvador, Ivan Castro in Managua, Erwin Seba in Houston and Kelly Dugan in Mobile, writing by Jim Loney in Miami; Editing by Pascal Fletcher and Eric Beech)

Florida Energy