A somber President Obama warned residents of the Gulf Coast not to \"tempt fate\" if asked by officials to evacuate as Tropical Storm Isaac took aim at the area. The president declared Louisiana a disaster area Monday in advance of Isaac\'s landfall. Forecasters expect the storm to reach hurricane strength and strike New Orleans for the anniversary of Hurricane Katrina, which killed some 1,800 and caused billions in damage. Obama Tuesday told reporters at the White House he wanted \"to encourage all residents of the Gulf Coast to listen to your local officials and follow their directions, including if they tell you to evacuate. We\'re dealing with a big storm and there could be significant flooding and other damage across a large area. Now is not the time to tempt fate. Now is not the time to dismiss official warnings.\" The president said he is getting updates from the Department of Homeland Security, the Federal Emergency Management Agency and the National Hurricane Center in Miami \"on preparations that are under way in the Gulf (of Mexico region).\" \"This storm isn\'t scheduled to make landfall until later today, but at my direction FEMA has been on the ground for over a week working with state and local officials in areas that could be affected -- from Puerto Rico and the U.S. Virgin Islands to Florida, and more recently, Louisiana, Alabama and Mississippi,\" he said. \"Yesterday I approved a disaster declaration for the state of Louisiana so they can get the help that they need right away, particularly around some of the evacuations that are taking place. And right now, we already have response teams and supplies ready to help communities in the expected path of the storm.\" Isaac was on the verge of becoming a hurricane early Tuesday, forecasters said, and was on a course that revived horrible memories for residents of Louisiana. Isaac was predicted to reach shore Tuesday night or early Wednesday morning in Louisiana with a storm surge of 6- to 12 feet, the National Hurricane Center said. Should the storm make landfall Wednesday in Louisiana, it will do so on the anniversary of Hurricane Katrina. Officials in Gulf Coast states have suggested residents along the coast head for higher ground.