Active Systems: The National Hurricane Center is issuing advisories on Tropical Storm Ian, located over the western Caribbean Sea, and on Tropical Storm Gaston, located a few hundred miles west of the western Azores. 1. Central Tropical Atlantic: An area of low pressure located several hundred miles west of the Cabo Verde Islands is producing persistent, but disorganized, showers and thunderstorms. Some slow development of this system is possible while it initially meanders for the next couple of days and then moves slowly north-northwestward late this week. * Formation chance through 48 hours...low...20 percent. * Formation chance through 5 days...low...30 percent.