Tropical Storm Fiona is on hurricane watch for Puerto Rico after strengthening overnight Friday. Forecasters say the storm could intensify late Saturday and Sunday as it gets closer to the island—possibly shedding 16 inches of rain, which could cause massive flooding and mudslides. Fiona has been moving west with winds whirring up to 60 mph and could impact the U.S. and British Virgin Islands with torrential downpours before hitting Puerto Rico. Continuing along its route, the storm is expected to make its way to the Dominican Republic by Sunday night and into Monday morning.