776 AXNT20 KNHC 201748 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1815 UTC Fri Dec 20 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 1200 UTC surface analysis and satellite imagery through 1800 UTC. ..MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near 01N10E and extends to 05N17W. The ITCZ continues from 05N17W to 02N51W. Scattered moderate convection is observed from 03N to 06N and between 35W and 40W. ...GULF OF MEXICO... A cold front extends across the far southern Gulf and Yucatan Channel. No significant convection is noted with this boundary. A surface trough parallels the coast of east Mexico, with scattered showers and isolated thunderstorms near the northern end of the trough axis. High pressure dominates the remainder of the Gulf of Mexico, resulting in moderate to fresh N-NE winds in the south- central Gulf. Seas in these waters are 3-5 ft. Moderate or weaker winds and slight seas prevail elsewhere. For the forecast, a cold front moving slowly southward through the southern Gulf of Mexico this morning will weaken and dissipate across the Yucatan Channel on Sat. Moderate to locally fresh N to NE winds will prevail across the basin through tonight. A reinforcing cold front will move southeastward through the northern and central Gulf tonight through this weekend. Fresh to locally strong N winds are expected along and behind this front in the northern Gulf late tonight. Moderate NE to E winds are then expected this weekend into early next week as the fronts weaken and a broad ridge shifts slowly eastward across the eastern U.S. and Gulf basin. ...CARIBBEAN SEA... Scattered moderate convection is occurring from 10N to 16N west of 80W, and scattered showers are noted off the coast of Panama, all influenced by the eastern extension of the East Pacific monsoon trough. A 1008 mb low is centered near 11N75W, and fresh to locally strong NE winds are occurring near the low. Elsewhere, ridging extends over the basin, and the pressure gradient between these features is supporting fresh E winds in the central and eastern Caribbean. Seas of 5 to 8 ft are occurring through the aforementioned areas. In the northwestern basin, moderate or weaker winds and slight seas are prevalent. For the forecast, fresh E to NE winds will prevail across the south- central through eastern Caribbean, as well as through the Atlantic Passages through midday as a strong pressure gradient prevails between the Colombian low and high pressure in the central Atlantic. Moderate to locally fresh NE to E winds will dominate the basin this weekend as a new ridge builds over the Caribbean from the NW. Looking ahead, high pressure will slide slowly eastward across the west and then central Atlantic early next week while a series of cold front will move off the southeastern United States. A building pressure gradient between these features will lead to fresh to locally strong NE to E winds across much of the Caribbean. ...ATLANTIC OCEAN... A cold front extends from a low pressure off the coast of the southeastern United States southwestward across the Bahamas and into northern Cuba, while a surface trough is analyzed across the southeastern Bahamas to eastern Cuba. Divergence aloft supports scattered moderate to strong convection east of the surface trough to 66W. The remainder of the SW North Atlantic, west of 55W, is dominated by a strong subtropical ridge over the NE Atlantic. Moderate to locally strong E winds are noted over much of the basin, especially between 45W and 75W. Rough seas are occurring in the area described, peaking around 11 ft. Elsewhere, a 1010 mb low is centered north of the area near 31N42W and a stationary front extends from 31N37W to 17N47W. Scattered moderate to locally strong convection is evident ahead of the frontal boundary to within 120 NM E of the front. Fresh to strong W to NW winds are noted to the southwest of the center of the low, where peak seas of 12 to 16 ft are occurring. Fresh to locally strong SE winds are also observed east of the low to about 30W. For the forecast W of 55W, widespread fresh to locally strong E to SE winds occurring north of 15N and east of the Bahamas will slowly diminish through tonight as high pressure in the central Atlantic weakens and drifts eastward. Seas in this area will slowly subside from north to south through early Sat. A cold front extending from 31N74W through the NW Bahamas and into western Cuba will decrease in forward speed today, before reaching from 31N68W to central Cuba by Sat morning, then weaken from 31N59W to east-central Cuba Sun morning. Fresh to strong W to NW winds and rough seas will occur behind the front N of 28N. Looking ahead, widespread fresh to locally strong NE winds and rough seas will redevelop across areas north of 20N Sun night through early next week as strong high pressure builds across the western Atlantic and into the local region behind the weakening front. $$ Adams