LAKE CHARLES, La. -- The National Weather Service evacuated its office in Lake Charles, Louisiana, as Hurricane Laura approached the Gulf Coast.
NWS meteorologists in Brownsville, Texas, assumed forecasting duties for the Lake Charles office. Lake Charles television station KPLC-TV also evacuated their studios in advance of the storm.
Mandatory evacuations ordered Tuesday for Calcasieu Parish impacted more than 200,000 residents, including in Lake Charles. Neighboring Cameron Parish to the south is also under a mandatory order.
Laura strengthened Wednesday into a menacing Category 4 hurricane, raising fears of a 20-foot storm surge that forecasters said would be "unsurvivable" and capable of sinking entire communities. Authorities implored coastal residents of Texas and Louisiana to evacuate and worried that not enough had fled.
The storm grew nearly 70% in power in just 24 hours to a size the National Hurricane Center called "extremely dangerous." Drawing energy from the warm Gulf of Mexico waters, the system was on track to arrive late Wednesday or early Thursday as the most powerful hurricane to strike the U.S. so far this year.
A Category 4 hurricane can cause damage so catastrophic that power outages may last for months in places, and wide areas could be uninhabitable for weeks or months.
PHOTOS: Gulf Coast braces for Hurricane Laura
The Associated Press contributed to this report.