(Reuters) - 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.