Tropical Storm Karen retained its strength as the system encountered shearing winds on a path through the Gulf of Mexico to the U.S. coast. The storm is no longer expected to become a hurricane, forecasters said.
Karen, with top sustained winds of 60 miles (95 kilometers) per hour, was about 275 miles south-southwest of the mouth of the Mississippi River at 8 a.m. New York time, moving north- northwest at 10 mph, said a National Hurricane Center advisory.
“Little change in strength is expected today and tonight, with some strengthening possible Saturday and Saturday night,” the center said.
The center’s tracking map forecasts Karen will make landfall as a tropical storm early Oct. 6 on the southeastern tip of Louisiana and then again close to Mobile, Alabama. The system may drive tides 3 to 5 feet (1 to 1.5 meters) above normal from the Mississippi to Mobile Bay.
Earlier forecasts had Karen reaching hurricane strength prior to coming ashore. A storm becomes a hurricane when its top winds reach 74 mph.
Tropical systems in the Gulf can disrupt U.S. and Mexican oil and natural gas operations. The region is home to 23 percent of U.S. crude production, 5.6 percent of gas output and more than 45 percent of petroleum refining capacity, according to the Energy Department.
There is a chance the storm will weaken, according to Matt Rogers, president of the Commodity Weather Group LLC in Bethesda, Maryland.
Wind shear pushed the system’s strongest thunderstorms off to the east of its low-level center, he said. Shear, when winds blow at varying speeds or directions at different altitudes, can tear at the structure of tropical storms.
“Karen may be a depression or a weak tropical storm upon landfall this weekend, but even the strongest models still keep the storm well below damaging threshold levels,” Rogers said. “Poor Karen is really struggling this morning.”
Anadarko Petroleum Corp. and Exxon Mobil Corp. were among the companies curbing energy production or evacuating workers in the Gulf as the storm advanced.
A hurricane watch, meaning storm conditions may arrive in two days, was posted from Grand Isle, Louisiana, to west of Destin, Florida. A tropical-storm warning is in effect from Grand Isle to the mouth of the Pearl River on the Louisiana- Mississippi Line.
New Orleans, the coast from Grand Isle to Morgan City, Louisiana, Lake Maurepas, Lake Pontchartrain and the area from Destin to Indian Pass, Florida, are under a storm watch.
As much as 7.8 inches of rain may fall across coastal Alabama and Florida, according to the Weather Prediction Center in College Park, Maryland. There’s a chance the storm will also touch off tornadoes, especially on its eastern side, said Bob Smerbeck, an expert senior meteorologist at AccuWeather Inc. in State College, Pennsylvania.
After Karen goes ashore, it is likely to track up the eastern side of the Appalachian Mountains, bringing heavy rains to the region, Smerbeck said. The rain may reach the cities of the U.S. Northeast next week.