By Daniel Trotta
July 21 (Reuters) - Tropical Storm Bertha churned across the northeastern Gulf of Mexico on Tuesday as tropical-storm conditions spread across portions of the northern Gulf Coast, while a separate weather system threatened severe thunderstorms and heavy rain across the U.S. Northeast.
Bertha, the second named storm of the Atlantic hurricane season, was centered about 105 miles (170 km) south-southeast of Mobile, Alabama, as of 7 p.m. CDT on Tuesday (0000 GMT on Wednesday), according to the National Hurricane Center, packing maximum sustained winds of 60 mph (95 kph) and moving west at 6 mph, the hurricane center said. It was expected to make landfall in Louisiana late Wednesday.
A gradual weakening was forecast on Wednesday through Friday.
Tropical storm warnings stretched from Florida's Panhandle westward into coastal Louisiana, including metropolitan New Orleans and Lake Pontchartrain. The hurricane center warned of dangerous surf and rip currents for summer vacationers.
Chevron said it was shutting in production at its Petronius facility in the Gulf as a precaution, and all associated personnel were being moved onshore in preparation for the storm. The U.S. oil major also said it was transporting nonessential personnel from its two other platforms.
The main threat from Bertha was expected to be heavy rainfall and localized flooding. Forecasts called for several inches of rain along parts of the central Gulf Coast from western Florida to southern Louisiana through Thursday.
Farther north, the National Weather Service warned that numerous severe thunderstorms were expected from the Ohio Valley into the Mid-Atlantic and Northeast states. Forecasters said swaths of damaging wind gusts were likely, and some tornadoes could develop as the storms tracked eastward.
New York City had been under a tornado watch for Tuesday night but that was rescinded. Elsewhere, tornadoes were possible in connection with severe storms within the Tennessee Valley and into the Mid-Atlantic, the weather service said.
The storm system was also forecast to bring periods of heavy rainfall to parts of the Northeast, increasing the risk of flash flooding in areas already saturated by recent wet weather.
(Reporting by Daniel Trotta in Vista, CaliforniaEditing by Rod Nickel)
