Obama issues Tropical Storm Isaac warning

US President Barack Obama has warned of significant damage and flooding from Tropical Storm Isaac, telling people in its path to take the "big storm" seriously and follow directions.
"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. You need to take this seriously," he said.
Isaac is bearing down on New Orleans seven years after the Bush administration's botched handling of the much bigger Hurricane Katrina became a political disaster and left a doom-laden case study for future presidents.