TAMPA, Florida — Thousands in Louisiana, Mississippi and Alabama were being told early Monday to leave their Gulf Coast homes ahead of the arrival of Tropical Storm Isaac as forecasters warned it was gaining strength as it followed the same path Hurricane Katrina took seven years earlier.

The governors of the three states each declared an emergency, with Alabama Gov. Robert Bentley ordering mandatory evacuations to begin at 8 a.m. for residents who live along the coast and for those in some low-lying areas inland.

“I am urging everyone to take precautions now, monitor weather warnings, and be prepared for whatever Isaac may bring,” Bentley said in a statement released Sunday.

A hurricane warning was issued for the northern coast of the Gulf of Mexico, from Morgan City, Louisiana, east to Destin, Florida, the National Hurricane Center said.

The tropical storm was expected to make landfall late Tuesday or Wednesday, coinciding with the seventh anniversary of Hurricane Katrina, though as a much weaker Category 1 hurricane, compared with 2005’s monster storm.

Isaac’s strength was holding steady Monday as it moved at 14 mph through the warm gulf waters, about 360 miles southeast of the mouth of the Mississippi River, forecasters said. The storm was packing maximum sustained winds of 65 mph, according to a hurricane center advisory.

The storm was “getting a little better organized” as it moved over the Gulf of Mexico, the center said.

It appeared early Monday that the storm’s ferocity would mostly bypass Florida’s west coast and the Republican National Convention in Tampa, where the schedule was pushed back a day by organizers over concerns about the storm.

Isaac’s eye is forecast to pass well west of Tampa.

After slamming into Haiti, where at least six people died in storm-related incidents Saturday, Isaac lashed Cuba and the Florida Keys.

There are so far some eerie similarities between Hurricane Katrina and Isaac, CNN meteorologist Dave Hennen said.

The forecast for Isaac and the one for Katrina in 2005 are almost identical, he said.

“Hurricane Katrina went on to become a dangerous Category 5 hurricane in the central Gulf of Mexico,” Hennen said.

On August 29, 2005, Katrina slammed into the Gulf Coast, killing roughly 1,800 people.

“We are just on high alert. I know the anxiety level is high,” New Orleans Mayor Mitch Landrieu said.

“The storm is somewhat uncertain. Out of an abundance of caution, we will begin to take these precautions as quickly as we can.”

Currently, there are no plans to order evacuations of New Orleans. If an evacuation is ordered, buses and trains would be used to move residents out of the city, Landrieu said.

The airport, the convention center and the Superdome would not be shelters of last resort as they were in 2005.

“We are much, much better prepared structurally than before,” he said, adding that “if you are called upon, you should leave.”

Louisiana Gov. Bobby Jindal, meanwhile, called on residents in coastal parishes prone to flooding to voluntarily evacuate. A mandatory evacuation was ordered for St. Charles Parish and for the east bank of Plaquemines Parish.

In Gulfport, Mississippi, authorities ordered the port cleared of cargo vessels.

Eight oil rigs and 39 production platforms in the gulf were evacuated by late Sunday, according to the U.S. Bureau of Safety and Environmental Enforcement. BP said it would evacuate its oil platform workers Monday.

“ExxonMobil continues preparations for heavy weather associated with Tropical Storm Isaac at its Gulf of Mexico and Mobile Bay operations,” a statement on the company’s website said early Monday. “We are closely monitoring weather updates, determining which of our facilities may potentially be in the path of the storm and preparing those structures for heavy wind and rain.”

As preparations continued on the northern Gulf Coast, Florida Gov. Rick Scott was assessing damage as Isaac skirted the state’s western coast, bringing strong winds and heavy rain.

“We are experiencing some minor outages in the southern part of the state,” he said at a news conference in Tampa. He said his main concern for Tampa was no longer a direct hit from Isaac but tropical storm-force winds.

Even with the storm’s predicted track, GOP officials decided to push back Monday’s scheduled start of the Republican National Convention in Tampa by one day, hoping the move will make it safer and easier for delegates to attend.

Officials said more than 550 flights were canceled at Miami International Airport on Sunday, while the possibility of flooding because of an anticipated storm surge forced the evacuations of portions of coastal Lee County, including Fort Myers Beach.

— CNN’s Chelsea J. Carter, Tom Cohen, Martin Savidge, Gary Tuchman, Jim Spellman and journalist Jean Junior Osman contributed to this report.