000 AXNT20 KNHC 251739 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1239 PM EST Mon Dec 25 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from Liberia, Africa and continues to 05N11W. The ITCZ axis extends from 05N11W to 05N23W to NE Brazil at 01N51W. Scattered moderate convection is from 04N-06N between 18W-26W, and from 01N-05N between 30W-40W. ...DISCUSSION... GULF OF MEXICO... As of 1500 UTC, a cold front extends from south Florida to 25N90W to 23N95W where it becomes stationary to the western Bay of Campeche near Veracruz, Mexico. A well defined band of mainly low clouds with enmbedded showers is associated with the front across the Gulf region. Broken low clouds are pooled against the Sierra Madre Mountains as seen on visible satellite imagery from recently upgraded GOES-E. Lines of low clouds in a northerly flow are moving across the Isthmus of Tehuantepec. Fresh to strong NE-E winds and seas of 5-7 ft are behind the front across the northern Gulf waters while mainly fresh northerly winds are noted west of the front over the SW Gulf. The cold front will reach south Florida this afternoon producing a wind shift, and little change in temperatures. The western half of the front will lift N as a warm front across the W Gulf beginning tonight, and stall across the far NW and N-Central waters on Thu. A low may form along the frontal boundary over the western Gulf on Wednesday. CARIBBEAN SEA... The most recent scatterometer data show strong to near gale force winds are across the south-central Caribbean near the coast of Colombia, and fresh to strong winds across the remainder of the central Caribbean. Moderate to locally fresh trades are noted elsewhere across the basin. Patches of low level moisture embedded in the trade wind flow are producing isolated to scattered passing showers across the Greater and Lesser Antilles from time to time. This cloudiness is more concentrated over the NW Caribbean between the Cayman Islands and the Gulf of Honduras. Little change in this weather pattern is forecast over the next two or three days. Strong trades will persist over the Central and SW Caribbean through Thu, with near gale force nocturnal winds near the coast of Colombia. Locally strong NE winds are expected through the Windward Passage on Tue evening. Large E swell will build seas to 9 ft E of the Lesser Antilles along 55W tonight and reach the E Atlc passages on Tue evening through Thu evening. ...HISPANIOLA... Low-topped trade wind showers will continue to move across the island. Mostly dry and stable conditions are expected to persist over the next couple of days under the influence of a mid-upper level ridge and associated strong subsidence. ATLANTIC OCEAN... As of 1500 UTC, a cold front enters the forecast area near 31N74W and extends SW across south Florida into the Gulf of Mexico. Mainly low clouds with embedded showers are related to the frontal boundary. Latest scatterometer data indicate fresh to strong SW winds within about 75 nm ahead of the front N of 29N, and mainly fresh NW winds in the wake of the front, forecast to stall from 29N65W to the Straits of Florida tonight into early Tue, then gradually weaken through Thursday. An area of showers and tstms is observed E of the Leeward Islands covering roughly the waters from 16N-22N between 50W-61W. This convective activity is at the western end of an elongated upper-level trough extending mainly E to W across the E and central Atlantic Ocean. The remainder of the forecast area is under the influence of a ridge anchored by a 1033 mb high located near the Azores. This system will undergo occasional intensity fluctuations, resulting in a rather tight pressure gradient across the waters N of the ITCZ/Monsoon Trough between the coast of Africa and the Lesser Antilles through at least Wednesday. Recent ASCAT passes provide observations of moderate to fresh winds around the southern periphery of the ridge E of the Lesser Antilles. Seas are in the 8-10 ft range within this area of winds based on altimeter passes. For additional information please visit http://www.hurricanes.gov/marine $$ GR