Subtropical Storm Alberto weakened as it neared landfall on the Florida Panhandle on Monday, a day after flooding from another storm tore through a historic Maryland town and swept away a would-be rescuer, officials said.Forecasters said Alberto could bring life-threatening high water to southern coastal states when it slams an area from Mississippi to western Georgia with up to 12 inches (30 cm) of rain and possible tornadoes.\r\nAlberto\u2019s top winds fell slightly to 60 miles an hour (96 km per hour) with the storm about 50 miles (80 kph) south of Panama City, Florida, the National Weather Service said. It was expected to reach land Monday afternoon or evening as it headed north at about 8 mph (13 kph).\r\n\u00a0\r\n\u201cThe basic idea is that it\u2019s going to run out of real estate for it to strengthen\u201d by picking up energy from the warm Gulf of Mexico waters, said Dan Petersen, a forecaster with the National Weather Service\u2019s Weather Prediction Center in College Park, Maryland.\r\n\u00a0\r\nAlberto, the first named Atlantic storm of 2018, spun up days before the formal June 1 start of the hurricane season.\r\nAuthorities in Florida\u2019s Franklin and Taylor counties issued mandatory evacuation orders for thousands of coastal residents. Florida, Alabama and Mississippi are under states of emergency.\r\nDeadly hurricanes in the United States and the Caribbean last year caused hundreds of billions of dollars in damage, massive power outages and devastation to hundreds of thousands of structures.\r\nThe storm will bring powerful winds and heavy rains as it moves into the Tennessee Valley on Tuesday and Wednesday, the hurricane center said. The storm, coming on the last day of the Memorial Day weekend, was expected to scramble holiday travel.\r\nA storm surge warning was in place from the Suwannee River to Navarre, Florida, and a tropical storm warning covered the area from the Suwannee River to the border of Florida and Alabama.\r\nAuthorities in Howard County, Maryland, said a 39-year-old man was missing after flash flooding from a separate storm tore through the historic downtown of Ellicott City on Sunday. The man was swept away as he tried to help rescue people from floodwaters.\r\nThe area had barely recovered from a devastating flood about two years ago that killed two people and damaged dozens of buildings.