UPDATE 1-Tropical Storm Cindy to hit U.S. Gulf Coast late Wednesday

(Adds Louisiana, Alabama states of emergency, energy port impacts, latest NHC storm track update)

June 21 (Reuters) - Tropical Storm Cindy is expected to make landfall on the Gulf Coast near the Texas-Louisiana border on Wednesday, threatening to bring flash floods from Texas to Florida, according to the National Hurricane Center.

Cindy's wind speed weakened on Wednesday and the storm center was located about 170 miles (270 km) south of Morgan City, Louisiana, with maximum sustained winds of 50 miles (85 km) per hour, the NHC said.

The storm was moving northwest at nearly 10 miles (17 km) per hour, and forecasters said they expect this motion to continue and landfall to be made along the Texas-Louisiana border, home to some of the nation's largest refineries.

Heavy rains and wind could disrupt oil supplies at the refineries and energy ports in Port Arthur, Texas and Lake Charles, Louisiana where large oil refining and chemical export operations are located, which could drive up gasoline prices.

Sabine Pilots, which guides ships in and out of the ports of Beaumont, Port Arthur, and Orange, Texas, suspended some operations on Wednesday, a spokesperson said. Cheniere Energy Inc declined to comment whether the storm was affecting loading of liquefied natural gas at its operations in the Sabine Pass.

Cindy was projected to drop between 6 and 9 inches (15-23 cm) of rain that could reach up to 12 inches in parts of Louisiana, Mississippi, Alabama and Florida, and cause "life-threatening flash flooding," the NHC said.

"It's a little stronger than it was yesterday, but the overall track is looking to be the same," said Stephen Strum, vice president of extended forecast services at Weather Decision Technologies in Tulsa, Oklahoma.

Rain will cause the biggest impact and fall most heavily from New Orleans to the Florida Panhandle, Strum added.

After the storm moves inland, rain will spread north-eastward across Arkansas and into portions of the Tennessee and Ohio Valley so that flooding concerns will continue through the weekend.

The Gulf of Mexico is home to about 17 percent of U.S. crude and 5 percent of dry natural gas output, according to the U.S. Energy Information Administration. More than 45 percent of the nation's refining capacity is along that coast, also home to 51 percent of total U.S. gas processing capability.

The Louisiana Offshore Oil Port, the largest privately owned crude storage terminal in the United States, suspended vessel offloading operations ahead of the storm but said Tuesday it expected no interruptions to deliveries from its hub in Clovelly, Louisiana.

Royal Dutch Shell said it suspended some offshore well operations, but production was so far unaffected. Anadarko Petroleum Corp said it had evacuated non-essential staff from its Gulf of Mexico facilities.

Governors in Louisiana and Alabama declared a state of emergency, while Texas increased its state of preparedness and Florida's governor warned residents in the northwest part of his state to stay alert for flooding and heavy rain.

There were also reports of voluntary evacuations from some coastal communities in Texas, including the Bolivar Peninsula in Galveston County, which is close to where the storm is expected to hit land.

The storm could cause a surge of up to 4 feet (1.2 meters) in isolated areas and possibly spawn tornados from southern Louisiana to the Florida Panhandle, the NHC said.

The Atlantic hurricane season runs from June 1 through Nov. 30. Most meteorologists forecast this year will be more active than normal. (Reporting by Scott DiSavino, Liz Hampton and Ernest Scheyder; Editing by Lisa Von Ahn and Chris Reese)