July 23 (Bloomberg) -- Tropical Storm Bonnie lost power crossing the southern tip of Florida and was downgraded to a depression as it moved into the Gulf of Mexico, the National Hurricane Center said.
The storm’s maximum winds were 35 miles per hour, down from 40 mph earlier in the day, according to a hurricane center bulletin released just before 5 p.m. Miami time. A storm must have winds of at least 39 mph to be considered a tropical storm.
The threat of Bonnie was enough to halt about 28 percent of the Gulf’s U.S. oil production and 10 percent of natural-gas output, the government reported. How Bonnie will affect the BP oil slick, the worst in U.S. history, is unknown because forecasters can’t exactly say where it will go and how strong it will be when it gets there.
“Assuming Bonnie doesn’t dissipate over the next day, the storm’s winds, coupled with a likely storm surge of 2 to 4 feet, will drive oil into a substantial area of Louisiana marshlands,” Weather Underground Inc. co-founder Jeff Masters said in his blog. However, he said, an expected landfall at low tide “will result in much less oil entering the Louisiana marshlands than occurred during Hurricane Alex in June.”
The latest storm track predicts the system will go ashore along the Louisiana-Mississippi line late tomorrow or early the next day. Bonnie was the second tropical storm of the 2010 Atlantic hurricane season.
Tropical storm warnings remain in effect from Destin, Florida, to Morgan City, Louisiana, including Lake Pontchartrain. All other warnings have been canceled. A warning means tropical storm conditions are expected within 36 hours, the hurricane center said.
Tropical-storm-strength winds extend about 85 miles from the center of the storm mainly on its northern and eastern sides, according to the center. Bonnie was about 35 miles south of Naples, Florida, and moving west-northwest at 18 mph.
The storm is forecast to leave as much as 3 inches of rain over Louisiana, Mississippi, Alabama and parts of Florida, according to the hurricane center.
Mississippi declared a state of emergency along its Gulf coast and activated National Guard troops, according to a statement from Governor Haley Barbour’s office.
“We may see oil come onshore and impact areas that have been previously unaffected by the spill,” Barbour said in the statement. “We have state agencies ready to respond to any storm or oil damage as quickly as possible.”
BP Plc said the storm’s high seas made it necessary to move ships working on the relief wells that will be used to kill the Macondo spill by pumping it full of mud and cement. That will set back completion of the plugging project to the end of August.
High atmospheric winds called shear are tearing at the storm’s structure and could rip it apart, leaving it a disorganized group of thunderstorms and low pressure.
“The environment in the Gulf of Mexico is forecast to remain unfavorable for strengthening mainly due to strong wind shear,” the center said.
Ken Graham, the National Weather Service meteorologist in charge of the Slidell, Louisiana, office, said two weather systems on either side of Bonnie will likely keep it from developing.
A high-pressure system over the U.S. East Coast, which will bring 95 to 100 degree temperatures to New York and Philadelphia, is east of the storm. To its west is an upper-level low-pressure system over the Gulf itself, Graham said.
Those two systems are creating the wind shear, Graham said. They are also steering the storm, according to a hurricane center’s analysis.
AccuWeather Inc. predicts Bonnie will fluctuate between a tropical storm and tropical depression through Saturday, according to a statement from the State College, Pennsylvania-based forecaster.
Royal Dutch Shell Plc, Enbridge Energy Partners LP and Transocean Ltd. evacuated non-essential personnel from rigs and platforms in the storm’s path.
Murphy Oil Corp. is shutting all of its production in the Gulf because of Bonnie, including its ThunderHawk, Habanero, Medusa and Front Runner platforms, Mindy West, a company spokeswoman, said in an e-mail.
Williams Cos. is shutting gas production and evacuating personnel at its Canyon Station platform in the eastern Gulf, the company said in a bulletin. It shut its Devils Tower station yesterday.
Oil and gas producers report that 2 rigs and 11 production platforms have been evacuated due to the storm, the Bureau of Ocean Energy Management, Regulation and Enforcement said today in a statement on its website. About 452,000 barrels of daily oil production are shut-in, along with 667 million cubic feet of gas.
The Gulf of Mexico is home to about 31 percent of U.S. oil output and about 10 percent of gas production, according to the Energy Department.
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