Active Systems: The National Hurricane Center is issuing advisories on Hurricane Fiona, located northeast of the southeastern Bahamas, and on Tropical Storm Gaston, located over the north-central Atlantic Ocean. 1. Western Tropical Atlantic: A tropical wave is producing shower and thunderstorm activity a few hundred miles east of the southern Windward Islands. The system continues to show signs of organization and it will likely become a tropical depression within the next two or three days. The disturbance is forecast to move west-northwestward across the southern Windward Islands by late today and then move toward the central Caribbean Sea later this week. Interests in the Windward Islands should closely monitor the progress of this system as heavy rainfall and gusty winds could affect these islands beginning later today. * Formation chance through 48 hours...high...70 percent. * Formation chance through 5 days...high...90 percent. 2. Eastern Tropical Atlantic: A tropical wave is forecast to move off the west coast of Africa on Thursday. Environmental conditions are forecast to be conducive for at least gradual development of the system for a couple days thereafter while the system moves slowly northward, between west Africa and the Cabo Verde Islands, through the end of the week. * Formation chance through 48 hours...low...10 percent. * Formation chance through 5 days...medium...50 percent. 3. East Central Tropical Atlantic: A tropical wave located several hundred miles west-southwest of the Cabo Verde Islands is producing disorganized shower activity. Slow development of this system is possible over the next several days as it moves northwestward and then westward over the tropical Atlantic. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 5 days...low...20 percent.