Updated

President Obama, before heading out on a three-state campaign trip, urged Gulf Coast residents Tuesday to heed the warnings of local officials as Tropical Storm Isaac approaches.

"As we prepare for Isaac to hit, I want to encourage all residents of the Gulf Coast to listen to your local officials and follow their directions," Obama said, speaking at the White House.

"We're dealing with a big storm and there's going to be significant flooding and other damage across a large area. Now's not the time to tempt fate."

Obama said that federal emergency officials are on the ground, and response teams and supplies are at the ready to help those in the storm's path. On the verge of becoming a hurricane, Isaac is expected to make landfall later in the day.

Obama said residents need to "take this seriously."

It's unusual for Obama to make a public address at the White House in advance of a tropical storm. But the president was taking extra care to show he's ready. Drawing more attention to this particular storm were the facts that it's making landfall roughly on the seventh anniversary of Hurricane Katrina and that it has become a focal point of the Republican National Convention in Tampa this week. The storm largely spared the convention site, but GOP officials have tried to stay mindful of its potential victims -- delaying the convention start and rearranging its speaker list so Gulf officials can stay home.

The last time Obama made any formal statement about an approaching storm was in August 2011, regarding Hurricane Irene.