000 AXNT20 KNHC 201742 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1242 PM EST Sat Jan 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 1745 UTC. ...SPECIAL FEATURES... Broad strong high pressure over the SW N Atlc waters will continue to move eastward while slightly strengthening the next two days. This is currently supporting fresh to near gale-force winds in the south-central Caribbean waters with the strongest winds being along the coast of NW Colombia. The pressure gradient in this region is expected to slightly increase tonight, thus leading to the development of gale-force winds along Colombia. Gale winds are expected to continue through Sunday morning, but remain in the strong to near-gale range through Monday. See the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean near 07N12W and continues to 03N16W to 01N21W. The ITCZ begins near 01N21W and continues along 01N40W to 01S50W. Scattered moderate rain showers are from 01N to 06N between 10W-18W and within 175 nm either side of the ITCZ. ...DISCUSSION... ...GULF OF MEXICO... A broad surface ridge extends from the SW N Atlc waters across Florida, the SE CONUS, into the Gulf and into inland Mexico. This setting is providing the basin with light to moderate return flow, except for locally fresh wind off the coast of Texas. A middle to upper level low centered between Louisiana and Mississippi extends a trough S-SW across the basin. To the east, SW flow associated with the NW periphery of a ridge centered in the south-central Caribbean supports diffluent flow, which is supporting cloudiness and possible isolated showers across the E Gulf, the Yucatan Channel and the Florida Straits. A weakness in the ridge analyzed as a surface trough along the SE coast of Florida into the Straits of Florida may enhance the shower activity for the SE Gulf. Otherwise, low level moisture convergence support isolated showers over Louisiana adjacent waters as indicated by radar imagery. The next cold front will come off the coast of Texas Monday morning, extend from the Florida Big Bend SW to near Tuxpan, Mexico Tuesday morning and then is expected to stall over South Florida to the central Gulf waters Wednesday. Remnants of the front will lift N late on Wed, with strong NE winds developing across the NW Gulf waters. ...CARIBBEAN SEA... A broad middle to upper level ridge centered over the south- central waters covers the Caribbean. Diffluent flow in the western periphery of this ridge along with moderate to high low level moisture support scattered showers within 175 nm west of a surface trough that extends along Nicaragua, Costa Rica and northern Panama adjacent waters. Isolated showers are elsewhere west of 75W. The tail of a weakening stationary front extends across the Windward Passage to near 18N80W supporting isolated showers in that region and over portions of Hispaniola. Shallow moisture in the trade winds may support scattered to isolated showers across Puerto Rico and adjacent waters. Otherwise, strong high pressure over SW N Atlc waters supports fresh to near-gale force winds in the south-central basin, increasing to gale-force off the coast of Colombia tonight through Sunday morning. See the Special Features section for more details. ...HISPANIOLA... Partly cloudy skies prevail across the island as the tail of a weakening stationary front extends across the Windward Passage towards western Jamaica adjacent waters. Isolated showers are occurring along the northern half of the Island. Similar weather conditions are forecast through Sunday morning as the front dissipates. Fresh northeasterly winds will continue across the Windward Passage through tonight and then it will limit to the Atlc approaches as the ridge slides towards the central Atlc waters. ...ATLANTIC OCEAN... Strong high pressure covers the SW N Atlc waters being anchored by a 1026 mb high near 29N72W. A weakness in the ridge is analyzed as a surface trough along the SE Florida coast SW towards the Straits of Florida. This surface feature in underneath diffluent flow aloft between a trough over the Gulf and a broad ridge covering the Caribbean Sea. This scenario support cloudiness and possible isolated showers in the northern Bahamas, the Great Bahama Bank and the straits. A broad middle to upper trough over the north- central Atlc with base near 30N continue to support a cold front that extends from 30N47W SW to 22N59W to 21N67W. From 21N67W, the front transitions to a weakening stationary front that traverses the Windward Passage. Scattered to isolated showers are N of 24N between 40W and 55W. The remaining eastern Atlc is under the influence of the Azores high that extends a ridge axis near 23N. The front in the central Atlc will continue to weaken as it loses support from aloft. A remnant surface trough is forecast in the central waters by Monday morning. The next cold front will exit the NE Florida coast Tuesday afternoon. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos