000 AXNT20 KNHC 260601 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Thu Aug 26 2021 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0000 UTC surface analysis and satellite imagery through 0540 UTC. ...SPECIAL FEATURES... Shower and thunderstorm activity gradually is becoming better organized in association with a trough of low pressure located a couple hundred miles south of Jamaica. While recent satellite wind data indicate that the system does not yet have a well-defined circulation, environmental conditions remain conducive for additional development, and a tropical depression is expected to form later today or tomorrow. The system is forecast to move northwestward over the northwestern Caribbean Sea later today, near Cuba and the Yucatan Peninsula of Mexico on Friday, and into the Gulf of Mexico this weekend. Regardless of development, heavy rainfall and flooding will be possible through the weekend in portions of Central America, the Yucatan Peninsula, Jamaica, the Cayman Islands, and Cuba. In addition, this system could bring dangerous impacts from storm surge, wind, and heavy rainfall to portions of the coasts of Louisiana, Texas, and the Mexican state of Tamaulipas late this weekend and early next week. However, uncertainty remains large since the system has yet to form. Interests in these areas should closely monitor the progress of this system and ensure they have their hurricane plan in place. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system later today, if necessary. The chance of formation chance through 48 hours is high. Precipitation: numerous strong is from 110 nm to 300 nm of a 1005 mb low pressure center, in the NE quadrant. The 1005 mb low pressure center is along a 77W tropical wave, near 14N. Isolated moderate to locally strong is elsewhere from 20N southward from 70W to the line that runs from E Honduras to SE Cuba. A broad trough of low pressure is producing disorganized showers and thunderstorms in the central tropical Atlantic Ocean, about 650 miles to the east-southeast of Bermuda. The environmental conditions are forecast to be generally conducive for development. It is likely for a tropical depression to form late this week or this weekend, while the system moves slowly northeastward through the central Atlantic. The chance of formation through 48 hours is medium. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 19W, from 18N southward, moving westward 10 to 15 knots. This wave just was added to the analysis at 26/0000 UTC. Precipitation: widely scattered moderate to isolated strong is within 270 nm to the west of the tropical wave from 11N to the southern part of the Cabo Verde Islands, and from 75 nm to the west of the tropical wave to 260 nm to the east of the tropical wave from 06N to 09N. An Atlantic Ocean tropical wave is along 36W/37W, from 18N southward, moving westward 10 to 15 knots. A 1008 mb low pressure center is along the wave near 11.5N. Precipitation: widely scattered moderate to isolated strong is from 07N to 09N between 29W and 31W, and within 340 nm of the 1008 mb low pressure center from the NE quadrant to the W quadrant. Some development of this system is possible during the next several days, while it moves west-northwestward 10 to 15 mph through the eastern tropical Atlantic Ocean. The upper level winds are forecast to become less conducive for development by early next week. An Atlantic Ocean tropical wave is along 57W, from 19N southward, moving W 10 to 15 knots. Precipitation: no significant deep convective precipitation is apparent in satellite imagery. A tropical wave is along 92W/93W, from 17N in the Isthmus of Tehuantepec of southern Mexico, moving westward 10 to 15 knots. Precipitation: widely scattered moderate to isolated strong is within 215 nm to the west of the tropical wave from 14N to 17N including in the Isthmus of Tehuantepec of southern Mexico. Isolated moderate is within 300 nm to the east of the tropical wave from 12N to 15N. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal border sections of Mauritania and Senegal, to the 1008 mb low pressure center that is along the 36W/37W tropical wave, to 08N40W and 08N47W. The ITCZ continues from 08N47W, to 10N61W just to the south of Trinidad. Precipitation: widely scattered moderate to isolated strong is within 125 nm to the south of the monsoon trough between 38W and 47W, and within 60 nm to the south of the ITCZ between the 57W tropical wave and 61W. ...GULF OF MEXICO... Upper level cyclonic wind flow covers most of the eastern half of the Gulf of Mexico. A surface trough passes through southern Louisiana. Precipitation: isolated moderate rainshowers span the Gulf of Mexico. A broad surface ridge extends from the NE corner of the area to the SW corner of the Gulf of Mexico, to the coast of Mexico near 20N. A surface trough will move into the eastern Gulf tonight into Thu morning, bringing fresh NE to E winds. Otherwise, high pressure pressure will dominate the basin through Fri, producing mainly gentle to moderate E to SE winds. Fresh winds will pulse west of the Yucatan Peninsula tonight and again Thu night. A broad area of low pressure is expected to form over the western Caribbean Sea during the next day or so from a tropical wave currently located north of Colombia. Environmental conditions are forecast to be conducive for development, and a tropical depression or tropical storm is likely to form late this week or over the weekend. The system is expected to move northwestward over the northwestern Caribbean Sea and near or across the Yucatan Peninsula of Mexico on Friday and into the Gulf of Mexico this weekend, where conditions are expected to be favorable for additional development. Mariners should closely monitor the progress of this system. It has potential for significant strengthening in the Gulf of Mexico. Expect a large increase in winds and seas this weekend in association with this system. ...CARIBBEAN SEA... Upper level cyclonic wind flow covers the Caribbean Sea to the northwest of the 77W tropical wave. The eastern extension of the eastern Pacific Ocean monsoon trough is along 10N/11N from 74W in Colombia, beyond Costa Rica, and into the eastern Pacific Ocean. Precipitation: scattered strong is along the coast/in the coastal plains of SE Nicaragua and NE Costa Rica. Widely scattered moderate to isolated strong is elsewhere from 15N southward from 80W westward. A broad area of low pressure is expected to form over the western Caribbean Sea during the next day or so from a tropical wave currently located along 77W north of Colombia. Environmental conditions are forecast to be conducive for development, and a tropical depression or tropical storm is likely to form late this week or over the weekend. The system is expected to move northwestward over the northwestern Caribbean Sea and near or across the Yucatan Peninsula of Mexico on Friday and into the Gulf of Mexico this weekend, where conditions are expected to be favorable for additional development. Based on the forecast, winds and waves will likely increase over the NW Caribbean Thu night through Sat. ...ATLANTIC OCEAN... A NE-to-SW oriented surface trough is passing through the Bahamas, anywhere from 90 nm to 270 nm to the east of Florida. The southern half of the surface trough passes through central Cuba, into the NW corner of the Caribbean Sea near 18N85W. Precipitation: widely scattered moderate to isolated strong is within 300 nm to the west of the surface trough, in Florida and in the easternmost parts of the Gulf of Mexico. Isolated moderate to locally strong is within 440 nm to the east of the surface trough. Broad upper level cyclonic wind flow is co-located with the surface trough and the precipitation. A surface trough located over the NW Bahamas will move into the eastern Gulf of Mexico by Thu morning. Fresh to strong NE winds are expected west of the trough axis, including the Florida Straits, through tonight. Otherwise, high pressure located just N of the forecast region will dominate the SW N Atlantic through Mon. Fresh to locally strong winds are expected to pulse N of Hispaniola during the evening hours through Sat night. $$ mt/gr/pp/jb