A weather system heading toward the Gulf Coast now has a 90% chance of becoming a tropical storm, putting cities from Houston to Mobile, Alabama on alert and prompting oil rig evacuations in the Gulf of Mexico.
The low-pressure system is now over the Florida panhandle, but is expected to travel into the Gulf of Mexico on Wednesday, where it will meet warm, open waters that will fuel the storm's intensity, according to CNN meteorologist Haley Brink.
There, it has a 90% chance of developing into a tropical storm over the next 48 hours, according to the National Hurricane Center. That is up from a 70% chance on Tuesday.
It isn't clear yet exactly where the storm will hit, Brink said, but models show it making landfall somewhere between Lake Charles, Louisiana and Mobile sometime Saturday.
It would be the first tropical system in the United States this hurricane season.
A tropical storm is an area of thunderstorms that produces a circular wind flow with winds from 39 to 73 miles per hour. With a lower wind speed, it would be a tropical depression. Higher, and it would be a hurricane.
Regardless of the classification this system develops into, Louisiana and Mississippi are forecast to see very heavy rain -- more than a foot in some places, Brink said.
The Gulf Coast area is prepared for intense weather.
"Tropical Storm, Hurricane, and Storm Surge Watches could be required for a portion of the northern Gulf Coast on Wednesday. An Air Force Reserve Unit reconnaissance aircraft is scheduled to investigate the disturbance tomorrow afternoon," the National Hurricane Service said.
Oil production companies operating in the Gulf of Mexico have also started to enact precautions.
Shell has evacuated all non-essential staff from eastern Gulf drilling rigs, with more action on the horizon depending on how the storm develops, spokeswoman Cindy Babski told CNN.
"Our top priorities are ensuring the safety of personnel, protecting the environment and minimizing impact to production and operations," Babski said.
Chevron has also evacuated some non-essential employees from the Jack St. Malo facility, with shut-in procedures initiated at five other facilities, spokeswoman Veronica Flores-Paniagua told CNN.
Potential storm surge has caused the National Weather Service to issue a flood warning for the Mississippi River, including New Orleans, through Saturday. The NWS said that the river could crest at 19 feet, or 2.3 feet below the record. The city is protected to a height of 20 feet.
The Flood Protection Authority said it will be closing several flood gates and structures in the New Orleans area starting Wednesday morning.