000 AXNT20 KNHC 201752 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1252 PM EST Thu Dec 20 2018 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 1730 UTC. ...SPECIAL FEATURES... ...GALE WARNING GULF OF MEXICO... The 12-hour forecast, from the 20/1200 UTC forecast, consists of: a cold front from 30N85W to 21N88W. Expect NW GALE-FORCE winds, and sea heights ranging from 10 feet to 13 feet, N of 25N W of 91W. Scattered to numerous rainshowers with thunder E of the cold front. The forecast for 24 hours, on Friday, consists of the cold front from 30N82W to 23N83W. Expect W-to-NW GALE-FORCE winds, and sea heights ranging from 12 feet to 20 feet, from 24N to 30N W of the cold front to 94W. Scattered to numerous rainshowers with thunder near the cold front. ...GALE WARNING ATLANTIC OCEAN... The 12-hour forecast, from the 20/1200 UTC forecast, consists of: SE-to-S GALE-FORCE winds, and sea heights ranging from 9 feet to 12 feet, N of 28N between 78W and 81W. The 24-hour forecast consists of: a cold front that will be approaching the area. Expect GALE-FORCE S-to-SW winds, and sea heights ranging from 9 feet to 17 feet, NW of the line that runs from 31N75W to 27N80W. The 48-hour forecast consists of: a cold front from 31N70W to 21N75W. Expect S-to-SW GALE-FORCE winds, and sea heights ranging from 12 feet to 24 feet, N of 27N between 68W and 77W. Please read the HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC...for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Liberia near 06N10W to 04N18W. The ITCZ continues from 04N18W to 02N30W, to 01N36W, and to 01N42W. Widely scattered moderate to isolated strong rainshowers are from 02N to 05N between 11W and 15W, from 06N to 12N between 25W and 36W, and from 03N southward between 35W and 52W in parts of Brazil. GULF OF MEXICO... A cold front extends from a SW Alabama 1002 mb low pressure center, to 28N88W in the Gulf of Mexico, to the central part of the Gulf of Mexico near 25N90W, southwestward to the northern sections of the Isthmus of Tehuantepec. A pre-frontal surface trough is within 120 nm to 180 nm to the east of the cold front, from 22N to 29N. A post-frontal surface trough is about 270 nm to the west of the cold front from 25N to SW Louisiana. Widely scattered moderate rainshowers are in a 45 nm wide line that runs from the Yucatan Channel, along the NW coast of Cuba, to the central part of the Florida west coast from 26N to 27N, and then toward NE Florida, and in the Atlantic Ocean from 29N northward from 70W westward. Broken to overcast multilayered clouds and other possible rainshowers are elsewhere to east of 94W in the Gulf of Mexico. Numerous rainshowers with thunder are along and ahead of the current cold front. The associated low pressure system will strengthen as it moves toward the north-northeast through Friday night. The cold front will move east of the Gulf, quickly, tonight. Strong to gale force southerly winds will develop ahead of the front today, followed by westerly gale-force winds behind the front. Very large seas are expected to build in the east central waters tonight and on Friday. Scattered rainshowers are expected behind the front. Surface high pressure will shift eastward across the central Gulf of Mexico on Saturday, then move across the Florida Panhandle on Sunday. CARIBBEAN SEA... An upper level ridge extends from northern sections of Colombia and NW Venezuela beyond Hispaniola. Rainshowers are possible, in clusters of broken low level clouds, across much of the Caribbean Sea, mostly from 85W eastward. 24-hour rainfall totals that are listed for the period that ended at 20/1200 UTC...according to the PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are 0.30 in Trinidad, 0.13 in St. Thomas in the U.S. Virgin Islands, 0.10 in San Juan in Puerto Rico, 0.02 in Curacao, and 0.01 in Montego Bay in Jamaica. Fresh to locally strong winds will continue across the south central Caribbean Sea through Monday. The fastest wind speeds are forecast to be near gale-force on Saturday night. Strong southerly wind flow is expected today ahead of a cold front in the Gulf of Mexico, which will enter the Yucatan Channel this evening. The front will reach from near the Windward Passage to Costa Rica by Saturday morning, then slowly move south and slowly dissipate through Sunday. Strong northerly winds are expected to the west of the front on Friday, increasing to near gale-force on Friday night. ATLANTIC OCEAN... A cold front passes through 32N40W to 27N50W, and to 25N58W. The front is stationary from 25N58W to 24N70W. Isolated moderate to locally strong rainshowers are from 27N northward between 35W and 46W. Rainshowers are possible elsewhere to the north of the line that passes through 32N34W to 24N40W, 22N60W, and 23N70W. One surface trough is along 42W/43W from 12N to 20N. Rainshowers are possible from 12N to 23N between 40W and 46W. A second surface trough is along 51W/52W from 12N to 22N. Rainshowers are possible within 200 nm on either side of the line that runs from 10N58W to 16N53W to 24N49W. Strong to near gale force southerly wind flow north of the Bahamas this morning, will increase to gale force, east and west of a strong cold front that will move off the the SE U.S.A. coast tonight. The cold front will reach from 30N75W to west central Cuba by early on Friday, and from 30N72W to the SE Bahamas and eastern Cuba on Friday evening, with gale force winds expected in the waters west of 72W. The front will begin to weaken as it reaches from Bermuda to 26N70W, and to the Windward Passage by early Saturday afternoon, and become stationary from 27N65W to SE Bahamas and to eastern Cuba on Sunday. The wind speeds and the sea heights will diminish across the region on Saturday and Sunday. For additional information please visit http://www.hurricanes.gov/marine $$ MT