UPDATE 2-U.S. energy companies monitor storms in Gulf

(Updates with additional company comment)

HOUSTON, Nov 6 (Reuters) - U.S. oil producers and refiners said operations were normal in and around the Gulf of Mexico on Friday as they monitored weather systems that could threaten offshore platforms and coastal facilities in the next several days.

Companies were faced with two systems -- former Hurricane Ida moving over Honduras and Nicaragua and disturbed weather in the southwestern Gulf -- which could threaten Gulf area operations, energy traders and weather forecasters said.

"No shutdowns at this time. We will continue to monitor the weather along the Gulf Coast and take appropriate precautions as necessary," said Bill Day, spokesman for Valero Energy Corp , largest U.S. refiner.

"While the current weather patterns are not impacting Shell (LSE: RDSB.L - news) operations, we are monitoring the situation," said a spokesman for Shell Oil Co , one of the largest oil and gas producers in the Gulf

Other companies who described themselves as watching and waiting included Chevron Corp (NYSE: CVX - news) , BP Plc and Marathon Oil Corp (NYSE: MRO - news) , Anadarko Petroleum Corp and Motiva Enterprises LLC.

The Gulf of Mexico accounts for 25 percent of domestic U.S. oil production and 15 percent of natural gas output. About 40 percent of the nation's refining capacity is concentrated on the U.S. Gulf coast.

Although there have been several serious storms elsewhere, the 2009 hurricane season, which ends Nov. 30, has had little or no effect on Gulf of Mexico oil and gas operations this year. (Reporting by Bruce Nichols and Kristen Hays in Houston, Haitham Haddadin, Joshua Schneyer in New York, Janet McGurty in Toronto; editing by Marguerita Choy)