The system’s top sustained winds strengthened to 65 miles (105 kilometers) per hour, up from 60 mph earlier. It was about 430 miles south of the mouth of the Mississippi River and moving north-northwest at 12 mph, the National Hurricane Center in Miami said at 2 p.m. East Coast time.
“It’s obviously the most exciting storm we’ve had this year in terms of U.S. impacts,” said Michael Schlacter, founder of Weather 2000 Inc. in New York. “It’s almost on the cusp of being a hurricane. The fact is, we can have a true hurricane right in the heart of the Gulf of Mexico.”
A storm becomes a hurricane when its top winds reach 74 mph, and if one gets into the Gulf it can affect 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.
A hurricane watch, meaning storm conditions may arrive in two days, was posted from Grand Isle, Louisiana, to Indian Pass, Florida. New Orleans, as well as the coast from Grand Isle to Morgan City, Louisiana, is under a tropical storm watch.
The center predicts Karen will reach hurricane strength tomorrow. While that might not happen, the watch was issued because it may be close, said Dennis Feltgen, a spokesman for the center.
The center’s tracking map forecasts Karen will make landfall as a strong tropical storm near the Florida-Alabama line early Oct. 6. It may drive tides 2 to 4 feet (60 to 120 centimeters) above normal from the Mississippi to Mobile Bay.
Karen is also expected to drop heavy rain on Mexico’s Yucatan Peninsula and on western Cuba through at least tomorrow, according to the center. Winds of at least 39 mph stretch 105 miles from Karen’s core.
Schlacter said Karen is most powerful on its eastern side, so area affected by that part of the storm will be hardest hit.
Karen may encounter wind shear as it crosses the Gulf, said Matt Rogers, president of the Commodity Weather Group LLC in Bethesda, Maryland. Shear is when winds blow at varying speeds or directions at different altitudes. That can tear at the structure a tropical system needs to maintain strength.
“I still think too much shear in the Gulf will mess this storm up,” Rogers said.
Tracking where a storm goes is much easier than predicting its intensity, Schlacter said. Karen might encounter more shear and weaken quickly, or hit an eddy of warm water and flourish, he said.
The hurricane center is also tracking Tropical Depression Jerry, which is about 890 miles west-southwest of the Azores. It is expected to break up in the next day. In the Pacific, there’s an area of disturbed weather 500 miles south of Manzanillo, Mexico, that has a 20 percent chance of becoming a tropical system in the next five days.
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