Isaac Reaches Hurricane Strength Nearing Landfall

Hurricane Isaac developed near the mouth of the Mississippi River today on a path that may take it near New Orleans and bring flooding rain to the lower Mississippi Valley, the National Hurricane Center said.

Isaac has halted 93 percent of U.S. oil production in the Gulf and 67 percent of natural-gas output, and forced evacuations from 503 production platforms and 49 rigs, the Bureau of Safety and Environmental Enforcement said today. Six Louisiana refineries were shut and three were running at reduced rates, idling 6.7 percent of U.S. capacity, according to data compiled by Bloomberg.

Isaac’s largest threat will be coastal flooding from a storm surge that may reach as high as 12 feet (3.7 meters) above normal if the hurricane strikes at high tide. As much as 7 to 14 inches of rain may fall across parts of Mississippi, Alabama and Louisiana where cotton, beans and rice wait to be harvested.

“The biggest problem may be with cotton,” David Streit, an agriculture meteorologist for Commodity Weather Group LLC in Bethesda, Maryland, said by telephone. “Almost two-thirds of the cotton is open boll at this point and none of it has been harvested.”

Isaac’s Location

The hurricane was 55 miles (88 kilometers) south-southeast of the river’s opening with top winds of 75 miles per hour, the center said in an advisory at 1 p.m. local time. It’s moving northwest at 10 mph on a track to landfall in southern Louisiana today or early tomorrow, possibly as a Category 1 storm. Hurricane-strength winds of at least 74 mph reach out 60 miles from the system’s core.

Heavy rain can damage the quality of the cotton crop or knock the bolls off the plants, Streit said.

In the longer term, Isaac’s rains may help to alleviate some of the drought across the Midwest, said Tom Downs, a meteorologist with Weather 2000 in New York. While it may come too late for this summer’s crops, the moisture may be enough to prepare the ground for winter planting, he said.

“It will definitely help moving forward and help to prevent this from becoming a multiyear thing,” Downs said. “This is where people got into trouble in the ‘30s and the ‘50s when it was back to back to back.”

Output Curtailed

The Gulf region is home to 23 percent of U.S. oil output, 7 percent of natural gas and 44 percent of refining capacity.

President Barack Obama declared an emergency for Louisiana, authorizing agencies to coordinate relief efforts. He urged residents today not to “tempt fate.”

A hurricane warning is in effect from Morgan City, Louisiana, to the Alabama-Florida border, including New Orleans.

The storm is forecast to hit Louisiana almost exactly seven years after Hurricane Katrina pounded ashore, levees protecting New Orleans failed and 1,800 people died.

The storm’s winds may peak at 80 mph and it may go ashore with sustained winds of 75 mph, according to a hurricane center discussion. Yesterday, the center forecast the storm may reach Category 2 strength with maximum winds of 100 mph or more.

Downs said the storm has stronger winds at high altitudes, and there’s a chance the storm could strengthen if those winds go lower.

The Louisiana Offshore Oil Port, the largest point of entry for crude coming into the U.S., stopped offloading tankers yesterday at the marine terminal, according to its website. Louisiana’s Port Fourchon, a base for support services to the Gulf’s deep-water oil and gas facilities was shutting yesterday, said Chett Chiasson, the port director.

The U.S. Coast Guard has closed the ports of New Orleans and Mobile, Alabama, as Isaac approaches, according to postings on the U.S. Department of Homeland Security’s Homeport website.