Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Sun Sep 12 2021 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Showers and thunderstorms associated with a broad area of low pressure over the southwestern Bay of Campeche have increased overnight and are showing signs of organization. Environmental conditions are conducive for additional development, and a tropical depression is expected to form later today or tonight while the system moves northwestward and then northward near the coast of northeastern Mexico. Additional development is possible through the middle of next week if the system remains over water, and interests along the western and northwestern Gulf coast should monitor the progress of this disturbance as watches may be required for portions of the coasts of northeastern Mexico and Texas later this morning or this afternoon. An Air Force Hurricane Hunter aircraft is currently en route to investigate the system this morning. Regardless of development, the disturbance will continue to produce heavy rain across portions of southern Mexico today, which may lead to flash flooding and mudslides. By late today, heavy rain is expected to reach portions of the Texas and Louisiana coasts, with a heavy rain threat continuing across those coastal areas through the middle of the week. Localized significant rainfall amounts are possible, potentially resulting in areas of flash, urban, and isolated river flooding. * Formation chance through 48 hours...high...90 percent. * Formation chance through 5 days...high...90 percent. 2. Disorganized showers and a few thunderstorms continue in association with a tropical wave located near the Cabo Verde Islands. Environmental conditions are becoming less conducive for development, and the chances of tropical depression formation are decreasing while the system moves westward over the far eastern tropical Atlantic. By the middle of the week, stronger upper-level winds and marginally warm ocean temperatures are expected to limit additional development. This disturbance could bring locally heavy rain across the Cabo Verde Islands today. * Formation chance through 48 hours...low...20 percent. * Formation chance through 5 days...low...20 percent. 3. A non-tropical area of low pressure is located over the far northeastern Atlantic a few hundred miles east-northeast of the Azores. This system is forecast to move south-southeastward towards warmer waters, which could allow the low to gradually acquire some tropical or subtropical characteristics during the next couple of days. After that time, the system is forecast to move inland over Portugal ending any further development chance. * Formation chance through 48 hours...low...20 percent. * Formation chance through 5 days...low...20 percent. 4. Another tropical wave is forecast to move off the west coast of Africa in a couple of days. Gradual development of this system is possible thereafter, and a tropical depression could form by the middle of the week while it moves westward across the eastern tropical Atlantic Ocean. * Formation chance through 48 hours...low...10 percent. * Formation chance through 5 days...medium...60 percent. 5. An area of low pressure is expected to form north of the southeastern or central Bahamas in a few days resulting from a tropical wave interacting with an upper-level trough. Gradual development of this system is possible, and a tropical depression could form later this week several hundred miles southeast of the Carolinas while it moves northwestward across the western Atlantic. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 5 days...medium...50 percent.