706 AXNT20 KNHC 121803 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sat Dec 12 2020 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 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1745 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: A rather strong cold front will move into the NW Gulf Sun night and across the rest of basin Mon and Mon night. Strong high pressure that will follow in the wake of the front will usher in fresh to strong north winds over mainly the western half of the basin, with the exception of northerly winds to gale force developing over sections of the western and SW Gulf Mon and Mon night. Wind and seas decrease Tue as the strong high pressure weakens while it shifts eastward across the area. Please read the latest HIGH SEAS FORECAST- https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the coast of Sierra Leone 08N12W to 65N20W, where latest scatterometer data indicates that it transitions to the ITCZ to 04N30W and to 05N39W and to 05N49W. Scattered moderate to isolated strong convection is within 60 nm south of the trough axis between 14W-17W. Scattered moderate convection is noted within 180 nm north of the ITCZ between 46W- 49W and within 120 nm north of the ITCZ between 33W-38W and between 41W-46W. Similar activity is within 60 nm north of the trough axis between 18W-20W and within 60 nm south of the ITCZ between 29W-31W and between 33W-37W. GULF OF MEXICO... Please see the SPECIAL FEATURES section above for details on an upcoming gale event to impact sections of the western Gulf. Broad upper-level ridging and associated anticyclonic wind flow spans the entire area. At the surface, a relatively weak cold front pushed into the NW Gulf this morning and as of 15Z, it is along a position from southwestern Louisiana to inland near Corpus Christi, Texas. Gentle to moderate north to northeast winds are behind the front. A pre-frontal trough is analyzed from near Morgan City, Louisiana southwestward to 27N94W and to inland Texas just north of Brownsville. Scattered showers are along and within 60 nm south of the trough between 95W-97W, while isolated showers are elsewhere along and near the trough. High pressure ridging stretches from the western Atlantic west-southwestward to northern Florida and to the north-central Gulf. Moist southerly winds to the south of the high pressure ridge and southeast of the cold front are present over comparatively cooler water temperature. This allowed for patchy areas of low stratus and fog to form during the overnight hours and into the morning over some sections of the western and north-central Gulf. Patches of low clouds, with possible isolated showers, are evident over the eastern Gulf and the rest of the central Gulf. Seas across the basin are in the 4-6 ft range, except for lower seas of 2-4 ft in the eastern Gulf. As for the forecast: The aforementioned cold front will become stationary by this evening, then transition to a warm front tonight as it lifts inland the northern and NW Gulf tonight into Sun morning. A rather strong cold front will move into the NW Gulf Sun night and across the rest of basin Mon and Mon night. Gale force winds are expected behind this front over some sections of the western and SW Gulf. See SPECIAL FEATURES above for details. CARIBBEAN SEA... Upper-level ridging covers the western Caribbean, Central America, Cuba and the Yucatan Peninsula, while broad troughing that extends from the central Atlantic is present over the rest of the Caribbean. Upper-level west-northwest winds over the western and central Caribbean transition to mainly west winds over the eastern Caribbean. Moderate to locally fresh trades continue cross the Caribbean east of 80W early this afternoon, except for fresh to strong northeast to east winds within 90 to 120 nm of the Colombian coast. Seas with these winds are in the 6-9 ft range. Gentle northeast winds are occurring west of 80W. Patches of low-level moisture in the form of scattered to broken low clouds with possible isolated showers being steered by the trades are noted across the sea. As for the forecast: The fresh to strong northeast to east winds near Colombia and offshore its coast will pulse nightly into the start of next week. A weakening cold front will move slowly southeastward across the Yucatan Channel and western Cuba Thu through Fri. ATLANTIC OCEAN... A cold front enters the area through 32N39W and extends to 29N44W, where it transitions to a stationary front to 25N54W, where it then become a shearline to 22N59W and to near 22N69W. ASCAT data from this morning revealed fresh northeast to east winds and a few strong wind occurrences north of the shearline to near 29N and also north of the cold front. Scattered moderate convection is seen within 120 nm northwest of the stationary front between 49W- 54W and along and within 60 nm south of the stationary front between 49W-53W. Areas of rain with embedded scattered showers and isolated thunderstorms are northwest of the stationary front and shearline to near 27N, and also from 20N-25N between 69W-72W. Broad and weak upper-level cyclonic winds continue to be present from 07N to 20N between 40W and 60W. A surface trough is analyzed along a position from 23N54W to 17N56W and to 11N56W. Isolated showers are along and near the trough from 15N-22N. A 1031 mb high center is analyzed to the north of the area near 35N58W. Associated anticyclonic flow is over the central Atlantic to the north of the stationary front and shearline. A 1027 mb high pressure center is analyzed over the far eastern Atlantic near 33N22W. Its related anticyclonic flow is over the waters north of 18N and east of the the stationary front and shear line features. As for the forecast: The stationary front and shearline will dissipate by early tonight or sometime tonight. Shower and thunderstorm activity will remain north of Hispaniola and Puerto Rico. High pressure building south north of the front and shearline will weaken. Strong southwest winds will develop in off the FLorida coast Mon in advance of the next cold front. $$ Aguirre