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Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sun Sep 12 2021

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. Showers and thunderstorms over the Bay of Campeche and southern 
Gulf of Mexico have been increasing during the past several hours 
near and east of a surface trough of low pressure.  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.  An Air Force Hurricane 
Hunter aircraft is scheduled to investigate the system this 
morning, and potential tropical cyclone advisories could be 
initiated later today.

Regardless of development, the disturbance will continue to produce 
heavy rain across portions of southern Mexico today, including the 
western Yucatan Peninsula, 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 coasts 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 
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...30 percent. 
* Formation chance through 5 days...low...30 percent.

3. A non-tropical area of low pressure is located over the far 
northeastern Atlantic several hundred miles 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 by the middle of next week.
* 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...near 0 percent.
* Formation chance through 5 days...medium...60 percent.

5. An area of low pressure is expected to form north of the 
southeastern Bahamas in a few days resulting from the northern end 
of a tropical wave interacting with an upper-level trough.  Gradual 
development of this system is possible, and a tropical depression 
could form by the middle of the 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...40 percent.

Forecaster Blake