Photo Gallery: Hurrricane Isaac 29/70

Heavy storm clouds hover over the skyline of downtown Miami as Tropical Storm Isaac's weather bands reach the Miami area aon Sunday, Aug. 26, 2012. Isaac gained fresh muscle Sunday as it bore down on the Florida Keys, with forecasters warning it could grow into a dangerous Category 2 hurricane as it nears the northern Gulf Coast. (AP Photo/The Miami Herald, Carl Juste) ORG XMIT: FLMIH101