000 AXNT20 KNHC 162339 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 639 PM EST Sat Dec 16 2017 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...SPECIAL FEATURES... ...Caribbean Sea Gale Warning... A strong high pressure is building to the north of the Caribbean Sea. A tight pressure gradient has developed in the south central Caribbean supporting fresh to strong trades across the basin. Gale-force winds will develop along the northwest portion of the Colombian coast each night starting tonight through early Monday. The sea heights will build to 10-13 feet in this area with the strongest winds this weekend, then reaching the 12-15 ft range by Sunday night/early Monday. Please read the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The monsoon trough passes through the coastal sections of Liberia near 07N12W to 06N15W. The ITCZ continues from 06N15W to 02N40W. Scattered showers are noted from 06N-15N and east of 31W. ...DISCUSSION... GULF OF MEXICO... A frontal boundary extends across the northern portion of the basin, analyzed as a stationary front from 27N82W to 27N88W, then as a warm front from that point to 26N96W. A surface trough, remnants of a cold front, extends along 95W between 22N-26N. Scattered showers are noted along these boundaries. Scatterometer data depicts moderate to fresh winds near these features, mainly west of 90W. Another surface trough extends across the Yucatan Peninsula with scattered moderate convection affecting the waters of the Yucatan Channel. Gentle to moderate winds are noted over the remainder of the basin with fair weather. Expect for a surface low to form over the northwest Gulf waters. This low will move northeastward pushing its front across the basin. CARIBBEAN SEA... Gale-force winds are expected to develop over the south-central Caribbean tonight. These conditions will continue pulsing each night through the weekend. Please refer to the Special Features section above for details. Fair weather prevails across the basin, with moderate to fresh trades. Little change is expected through the next 24-48 hours. ...HISPANIOLA... Fair weather prevails across the island. Isolated showers could develop over the area each day in the afternoon hours due to orographic lifting and daytime heating. ATLANTIC OCEAN... A pair of cold fronts extends across the west Atlantic. The first was analyzed from 31N62W to 28N80W. The second front extends from 31N65W to 30N80W. Scattered showers are noted along the fronts. A surface trough extends from 28N67W to 24N75W with isolated showers. To the east, a surface trough extends from 24N52W to 14N53W with no convection. The remainder of the area is under the influence of a surface ridge, anchored by a 1031 mb high centered near 36N27W. Expect for the cold fronts to merge in the west Atlantic and continue moving southeast with convection. Little change is expected elsewhere. For additional information please visit http://www.hurricanes.gov/marine $$ ERA