New Orleans threatened by floods as big storm forms

The US city of New Orleans was under a storm-surge watch Wednesday along with a stretch of Louisiana coast as a tropical storm formed in the Gulf of Mexico, threatening the region with potentially life-threatening rains. "Conditions appear favorable for this system to strengthen to a hurricane as it approaches the central Gulf Coast by the weekend," the Miami-based National Hurricane Center said. A flash flood emergency was declared earlier Wednesday in New Orleans, part of which is built below sea level and was devastated by Hurricane Katrina in 2005.