For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Central Tropical Atlantic: Shower and thunderstorm activity associated with an area of low pressure located several hundred miles east of the Lesser Antilles has continued to increase and become more concentrated overnight. However, recent satellite wind data indicate that the circulation remains elongated and lacks a well-defined center. Although environmental conditions are only marginally conducive, additional gradual development of this system is expected and a tropical depression is likely to form within the next couple of days. The disturbance is forecast to move slowly toward the west-northwest, toward the adjacent waters of the northern Leeward Islands. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service. * Formation chance through 48 hours...medium...60 percent. * Formation chance through 5 days...high...80 percent. 2. Eastern Tropical Atlantic: A broad area of low pressure located between the west coast of Africa and the Cabo Verde Islands is producing disorganized showers and thunderstorms. Some gradual development is possible, and the system could become a short-lived tropical depression over the far eastern Atlantic during the next couple of days. By late this week, environmental conditions are forecast to become increasingly unfavorable for further development. Regardless, the system could bring locally heavy rainfall to portions of the Cabo Verde Islands through Thursday. * Formation chance through 48 hours...low...20 percent. * Formation chance through 5 days...medium...40 percent. 3. Central Subtropical Atlantic: An area of low pressure is expected to form within the next day or so along a decaying frontal zone over the central subtropical Atlantic. Environmental conditions are expected to be conducive for some gradual development thereafter, and a tropical or subtropical depression could form later this week while the system drifts generally eastward. * Formation chance through 48 hours...low...30 percent. * Formation chance through 5 days...medium...50 percent.