000 AXNT20 KNHC 202228 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sat Sep 21 2024 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 1800 UTC surface analysis and satellite imagery through 2200 UTC. ...SPECIAL FEATURES... Potential Heavy Rainfall in Central America: Latest satellite imagery shows scattered to numerous moderate to strong convection associated with a developing Central American Gyre (CAG), over the W Caribbean W of 76W. This activity is expected to persist through this weekend and into the middle of next week while moving northwestward, becoming focused in El Salvador, Guatemala, and southern Mexico by late next week. The heaviest rainfall is expected along the south and west coasts of Mexico, Guatemala, El Salvador, Nicaragua, and Costa Rica. Heavy rainfall will lead to increased potential for life-threatening flash flooding and mudslides in these areas. It is recommended that residents in the aforementioned areas stay alert on the latest information from their meteorological agencies. Please refer to the Tropical Weather Discussion for the Eastern Pacific at website: https://www.hurricanes.gov/text/MIATWDEP.shtml for more details on rainfall across the Pacific coastal areas of these nations. ...TROPICAL WAVES... A tropical wave has its axis near 89W, from 20N southward, moving W at 10 kt. Scattered moderate convection is noted near the northern portion of the wave axis, generally from 18N to 21N between 86W and the wave axis. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the basin from the west coast of Africa near 11N16W and continues westward to near 08N38W. The ITCZ then stretches from 08N38W to near 10N46W. Scattered moderate convection is noted from 04N to 09N and E of 25W. The East Pacific monsoon trough also extends across the southwest Caribbean to inland Colombia. Convection in this area is associated with a developing Central American Gyre, see the SPECIAL FEATURES section above for more details. ...GULF OF MEXICO... A diurnal surface trough is analyzed over the Bay of Campeche along 92W, with scattered showers developing along and near the northern portion of the trough axis. Another surface trough is noted over the SE Gulf along 24N and E of 85W with no notable convection nearby. Otherwise, high pressure of 1013 mb centered near 29N94W is dominating Gulf weather, bringing dry conditions, light to gentle winds, and seas of less than 3 ft. For the forecast, moderate to locally fresh winds may pulse in the eastern Bay of Campeche nightly through the next several days. Looking ahead, a broad area of low pressure could form by the early to middle part of next week over the northwestern Caribbean Sea. Thereafter, gradual development of this system is possible, and a tropical depression could form as the system moves slowly to the north or northwest over the northwestern Caribbean Sea and into the southern Gulf of Mexico through the end of next week. There is a medium chance of tropical cyclone formation in the next seven days. Regardless of development, winds and seas will start increasing across the SE Gulf early next week. ...CARIBBEAN SEA... Please refer to the SPECIAL FEATURES section above for details on convection in the southwest Caribbean associated with a developing Central American Gyre (CAG). Convergent surface winds are leading to the development of scattered showers and isolated thunderstorms in the far eastern Caribbean. Otherwise, moderate to fresh easterly winds and seas at 3 to 5 ft are evident in the central basin. Gentle to moderate SE to E winds and 2 to 4 ft seas are seen across the remainder of the basin. For the forecast, moderate to fresh winds and moderate seas are expected across the E and central Caribbean through at least Sat. Looking ahead, a broad area of low pressure could form by the early to middle part of next week over the northwestern Caribbean Sea. Thereafter, gradual development of this system is possible, and a tropical depression could form as the system moves slowly to the north or northwest over the northwestern Caribbean Sea and into the southern Gulf of Mexico through the end of next week. There is a medium chance of tropical cyclone formation in the next seven days. ...ATLANTIC OCEAN... A surface trough that extends roughly along the Gulf Stream offshore Florida is inducing scattered moderate convection in its immediate vicinity. An upper-level trough is also helping to generate areas of scattered moderate convection over and to the northeast of the Bahamas and the Turks and Caicos Islands. A 1006 mb area of low pressure centered near 25N55W. Another low is centered near 26N43W. A surface trough connects both lows along 25N between 40W-63W. Scattered moderate convection prevails along the trough. To the north of these features, moderate to fresh E winds generally north of 26N between 52W and 58W, along with seas of 8 to 9 ft in this area. Environmental conditions do not appear conducive for significant development of any of these systems during the next couple of days while it drifts northwestward at about 5 kt over the central or western subtropical Atlantic. Elsewhere, light to gentle winds and seas at 4 to 7 ft dominate most of the basin. For the forecast W of 55W, a weak cold front will move off the SE coast of the US tonight and slowly move across the waters N of 25N through Mon. Fresh NW winds and moderate seas will prevail along and W of the front. $$ ERA