 On May 12 , a persistent area of thunderstorms formed within a monsoon trough 220 miles ( 350 km ) southwest of Palau . Satellite imagery revealed a weak low @-@ level circulation . Initially , the Joint Typhoon Warning Center ( JTWC ) forecast the storm to not strengthen . The following day , forecasters saw that the storm was strengthening and upgraded the system to tropical depression status . Forecasters at the Philippine Atmospheric , Geophysical and Astronomical Services Administration designated the storm as Tropical Depression Dindo . 
