000 AXNT20 KNHC 201048 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sun Dec 20 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 0600 UTC surface analysis and satellite imagery through 1030 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: Near gale to gale force south to southwest winds are occurring over the NW Gulf within about 90 nm southeast of a 1014 mb low pressure system that is near 29N91W, with a trailing cold front that extends from it to 26N94W and to inland Mexico at 23N98W, and also within 60 nm southeast of the squall line segment that extends from near 27N91W to 26N93W. These conditions are forecast to diminish by early this afternoon as the low pressure reaches to just south of the western Florida panhandle, with the cold front extending from it to near 25N91W and to the SW Gulf. Please read the latest High Seas Forecast at https://www.nhc.gov/text/MIAHSFAT2.shtml for more details. West Atlantic Gale Warning: A cold front will move across the west Atlantic starting on Monday. Gale force SW winds are expected to develop as the front approaches the area and then moves east on Monday. These conditions will dissipate by Monday night. Please read the latest High Seas Forecast at https://www.nhc.gov/text/MIAHSFAT2.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coastal sections of Sierra Leone near 08N13W to 07N16W, then transitions to the ITCZ to 07N16W to the coast of Brazil near 04N51W. Scattered moderate convection is within 120 nm north and 60 nm south of the ITCZ between 25W-45W. GULF OF MEXICO... Please see Special Features section above for details on an ongoing Gale event over a section of the NW Gulf. A positively-tilted upper shortwave trough stretches from eastern Arkansas southwestward to eastern Texas. This feature is driving a cold front that extends from a 1014 mb low near 29N91W, to 23N98W. A vigorous pre-frontal squall line is analyzed from 29N90W to 25N94W. Scattered to numerous moderate convection is noted north of 23N between 85W-95W. This activity is capable of producing strong gusty winds and numerous lightning strikes. The pressure gradient between the high pressure over the west Atlantic and lower pressure over the Gulf is supporting moderate to fresh winds across the basin. Seas are in the range of 3-5 ft, except for higher seas of 4-6 ft in the NW Gulf. As for the forecast: The high pressure over the eastern Gulf will continue to shift eastward through Sun night in the response to eastward advancement of the low pressure and cold front. The front is forecast to reach from the central Gulf Coast to the western Bey of Campeche on Sun, and from southwest Florida to the Yucatan peninsula on Mon before exiting the southeastern Gulf early on Mon. Expect for the present ongoing shower and thunderstorm activity to gradually shift to the eastern Gulf through tonight. Moderate to fresh southeast winds are expected in the NW Gulf on Wed. By Thu, a strong cold front is forecast to move across the basin, with the possibility of gale force northwest to north winds following in behind it over the SW and west-central Gulf waters. CARIBBEAN SEA... Latest scatterometer data depicts fresh to strong northeast to east winds over the south-central Caribbean. Fresh northeast winds are noted south of Hispaniola and over the Windward Passage. These winds are the result of a tight gradient between high pressure well north of the area along the U.S. Mid-Atlantic coast and lower pressure that is typically over NW Colombia and southwestern Caribbean. These winds will continue into this morning as the high pressure remains in place. Scattered showers are noted moving quickly over the Greater Antilles and adjacent waters. As for the forecast: High pressure north of the area will continue to support moderate to fresh trade winds across much of the area. Highest winds and seas will continue to be in the southern Caribbean, near the coast of Colombia, pulsing at nighttime through the forecast period. A cold front will slide southward into the NW Caribbean by the end of the week enhancing winds/seas. ATLANTIC OCEAN... A cold front extends from near 32N46W to 26N55W, where it transitions to a stationary front to 22N75W. Scattered showers are noted along the cold front. Mainly moderate northerly winds are noted in the wake of the front, with an area of fresh winds just to the north of the southeastern Bahamas as were detected by an ASCAT pass from last night. Strong high pressure is building in over the western Atlantic behind the front. A surface ridge prevails over the east Atlantic, anchored by a 1025 mb high pressure center located near 30N25W. Fresh trade winds are along the southern periphery of the ridge affecting the Cabo Verde Islands and regional waters were seen in a partial ASCAT pass from last night. As for the forecast: The tail end of the stationary front will dissipate this morning, while the cold front will continue to push eastward and dissipate through the next 24-36 hours. The next cold front will move off the Florida coast on Mon, reach the southern Bahamas and southern Cuba by Tue, and continue moving eastward on Wed. Strong to gale force winds will develop ahead of the front off the Florida coast and north of the Bahamas on Mon. Fresh to strong winds will prevail behind the front. By the end of the week, a strong cold front will push off the northeast Florida coast enhancing winds and convection. $$ ERA