000 AXNT20 KNHC 101738 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1238 PM EST Sat Mar 10 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 1715 UTC. ...SPECIAL FEATURES... This morning, scatterometer data indicated minimal gale force winds across the Gulf of Venezuela, while an altimeter pass showed seas of 10-12 ft near the coast of Colombia. Although winds are forecast to diminish below gale force this afternoon and evening, minimal gale conditions are expected again across the Gulf of Venezuela, and near the coast of Colombia tonight. Seas are forecast to build to 11-13 ft near the coast of Colombia. Please see the latest Atlantic Ocean High Seas Forecast product under AWIPS/WMO headers HSFAT2/FZNT02 KNHC, for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Sierra Leone near 08N13W to 06N20W. The ITCZ continues from 06N20W to 03N30W to 00N40W to 00N50W. Scattered moderate convection is from 03N-06N betwen 11W-17W. Isolated moderate convection is from 01N- 04N between 27W-33W. ...DISCUSSION... GULF OF MEXICO... An area of showers and thunderstorms has flared up across the northern Gulf waters, mainly N of 25N E of 94W, and is associated with a vigorous short-wave trough forecast to move eastward across the Gulf region today. Lightning density indicates frequent lightning with this observed convective activity. This system could increase the likelihood of showers with isolated tstms over south Florida later today into the evening hours as the short-wave trough digs across the eastern Gulf. As of 1500 UTC, a high pressure of 1023 mb located E of Florida near 30N76W extends a ridge across the Gulf, producing moderate to fresh SE-S winds and seas of 4-7 ft, except 1-3 ft over the NE Gulf. Winds and seas could be higher near tstms. A cold front will move off the Texas coast Sun afternoon, then race southeastward across the entire basin through early Mon, and across the Straits of Florida on Mon evening. Strong northerly winds and building seas will follow the front. A brief instance of minimal gale force winds is possible behind the front over the west-central waters early on Mon, and over the SW Gulf waters by Mon evening. Seas are forecast to build to 11-12 ft with the strongest winds. A ridge will extend from northeast Texas to the Straits of Florida on Tue, and shift NE on Wed. CARIBBEAN SEA... A vigorous short-wave trough, currently moving across the Gulf of Mexico, could increase the likehood of showers with isolated tstms across western Cuba later today into the evening hours. The Galvez-Davison Index indicates the potential for scattered shallow convection and isolated to scattered tstms. The most recent scatterometer passes provide observations of fresh to strong winds across the east and central Caribbean, and moderate to fresh winds across the NW Caribbean, with fresh SE winds over the Yucatan Channel, and fresh NE winds over the Windward Passage. Fresh to strong trades will continue across the waters east of 80W, except increasing to minimal gale force during the overnight hours tonight off the NW coast of Colombia and Gulf of Venezuela. Please see Special Features section. The largest areal extent of the strong winds over the central Caribbean is expected over this weekend, with high pressure centered NE of the region. As the high pressure shifts east early next week, the wind speeds over the Caribbean will decrease. A strong cold front is forecast to enter the Yucatan channel and far NW Caribbean on Mon, reach from central Cuba to the Gulf of Honduras on Mon night, stall from Hispaniola to Nicaragua on Tue, and dissipate on Wed. Moderate to fresh northerly winds and building seas in the 5-7 kt range are expected in the wake of the front over the NW Caribbean. ATLANTIC OCEAN... As of 1500 UTC, a 1023 mb high pressure is located E of Florida near 30N76W and extends a ridge across Florida into the Gulf of Mexico. A cold front stretches from 31N55W to 24N65W, where it becomes stationary to near the approach to the Windward Passage. Scattered showers and isolated tstms are seen along the frontal boundary, but mainly E of 67W. Remnants of the front will lift north tonight into Sun ahead of another cold front moving off the northeast Florida coast on Sun night. This second cold front will extend from near 31N75W to northwest Cuba late Mon, and stall from 27N65W to central Cuba on Wed. Fresh to strong SW winds will develop ahead of this cold front over the waters N of 27N W of 70W early on Mon, and expand across the waters N of 27N W of about 62W by early Mon afternoon. Fresh to strong W-NW winds will follow the front Mon through Tue morning. E of front, a pair of 1025 mb high centers are over the east and central Atlantic near 30N33W and near 26N46W respectively. Farther E, a weakening cold front crosses between the Canary Islands and the coast of Africa. Seas of up to 13-14 ft are noted per altimeter data across the waters N of 20N E of 30W in northerly swell. For additional information please visit http://www.hurricanes.gov/marine $$ GR