000 AXNT20 KNHC 162318 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0015 UTC Tue Dec 17 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 2300 UTC. ...SPECIAL FEATURES... Western Atlantic Significant Swell Event: Large NE swell generated by earlier strong gale winds across the northern Atlantic is persisting across the west and central Atlantic. It is sustaining seas of 12 to 14 ft north of 27N between 45W and the northern Bahamas. Fresh to strong NE to E winds are occurring over this area. The swell will slowly decay tonight allowing for seas to subside below 12 ft by Tue. Please refer to the latest High Seas and Offshore Waters Forecasts issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFAT2.html and https://www.nhc.noaa.gov/marine/offshores.php for more detail. ...MONSOON TROUGH/ITCZ... The monsoon trough is analyzed from 06N10W to 06N14W. The ITCZ extends continues from that point to 02N51W. Scattered moderate convection is in the vicinity of the ITCZ S of 10N and W of 24W. ...GULF OF MEXICO... Strong high pressure over the western Atlantic extends a ridge across the eastern of the United States into the Gulf of Mexico. The resultant gradient is allowing for fresh to strong NE to E winds along with seas of 6 to 8 ft to exist over the southeastern and east-central Gulf sections, including the Straits of Florida and Yucatan Channel. Moderate E to SE winds are elsewhere, except for moderate to fresh NE to E winds over the NE part of the basin. Seas are 4 to 6 ft elsewhere, except for higher seas of 6 to 8 ft over the central part of the Gulf from 22N to 26N between 87W and 91W. For the forecast, the high pressure will continue to support fresh to strong NE to E winds and moderate to rough seas over the eastern Gulf, including the Straits of Florida through tonight. Thereafter, gentle to moderate winds and slight to moderate seas are expected through Wed. Looking ahead, a weak cold front will reach the NW Gulf of Mexico by Wed and dissipate over the northern Gulf by early Thu. High pressure in the wake of the front will bring gentle to moderate northerly winds and slight to moderate seas Thu through Sat. ...CARIBBEAN SEA... A surface trough is analyzed from central Bahamas to 16N82W. Scattered showers and thunderstorms prevail in the vicinity of the trough. Convergent trade winds are causing isolated thunderstorms across the eastern basin, including waters near Puerto Rico and the Virgin Islands. Fresh to strong NE winds along with seas of of 5 to 7 ft are over the northwestern Caribbean. Gentle to moderate NE to E winds, with seas of 3 to 5 ft seas prevail elsewhere in the Caribbean Sea. For the forecast, the pressure gradient between strong high pressure over the western Atlantic and the surface trough will continue to support fresh to strong NE winds in the lee of western Cuba, including the Yucatan Channel through tonight. High pressure will build in the wake on the trough, enhancing the trade wind flow over the central Caribbean, mainly at night, tonight through Fri. ...ATLANTIC OCEAN... Please read the SPECIAL FEATURES section above for information on the significant swell event. A surface trough extends from the NW Caribbean to central Bahamas. Another trough is analyzed from 25N58W to 18N63W. Fresh to strong NE winds and scattered showers/isolated thunderstorms are noted in the vicinity of the troughs, mainly W of 55W. A cold front passes through 31N43W to 29N51W to 31N60W. Strong to near gale- force NE winds and rough to very rough seas are from 29N north between 45W and 55W. Fresh or slower winds, and rough seas in N to NE swell, are elsewhere from 16N northward and to the east of 55W. Moderate to fresh winds cover the remainder of the Atlantic, along with moderate seas. For the forecast W of 55W, the tight pressure gradient between strong high pressure over the western Atlantic and the surface trough continues to support fresh to strong NE winds and rough seas over most of the waters west of 65W through tonight. Fresh to strong E winds will prevail E of the Bahamas through Wed as a ridge builds towards the western Atlantic. Looking ahead, the next cold front is forecast to move off the northeastern Florida coast Wed night, reach from near 32N71W to the central Bahamas by late Thu night and stall. A strong cold front may quickly merge with the stalled front late on Fri, followed by fresh to strong NW winds. $$ ERA