000 AXNT20 KNHC 200005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Mon Mar 19 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...SPECIAL FEATURES... ...ATLANTIC OCEAN GALE WARNING... The 30-hour forecast, starting at 19/1800 UTC, is for a cold front to be along 31N80W 30N81W. Expect: N of 29N E of the cold front to 76W SW WINDS 25 to 35 knots. Seas 9 to 12 feet. The 48-hour forecast consists of: the cold front along 31N71W 26N75W 22N79W. N of 30N between 72W and 78W SW to W WINDS 30 to 35 knots. Seas 12 to 17 feet. ...GULF OF MEXICO GALE WARNING... The 24-hour forecast, starting at 19/1800 UTC, is for a cold front to be along 30N83W 18.5N93W. Expect: N of 25N E of the cold front SW WINDS 20 to 25 knots with FREQUENT GUSTS TO GALE FORCE WITHIN 30 NM OF THE COAST FROM SUWANNEE FLORIDA TO PASCAGOULA MISSISSIPPI. SEAS less than 8 feet. N of 26N W of the cold front to 93W W to NW winds 20 to 25 knots with FREQUENT GUSTS TO GALE FORCE WITHIN 30 NM OF THE COAST E OF PASCAGOULA MISSISSIPPI. Seas less than 8 feet. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Sierra Leone near 08N13W, to 06N15W and 03N21W. The ITCZ continues from 03N21W to 02N25W 03N40W, to 03N51W at the coast of Brazil. Precipitation: isolated moderate to locally strong rainshowers, in a disorganized pattern, are from 08N southward from 60W eastward. ...DISCUSSION... GULF OF MEXICO... As of 1500 UTC, a prefrontal trough has entered the NW Gulf of Mexico. A cold front is just inland over Texas. Scattered showers are along the front. Weak ridging extends from southeast Florida to the north central Gulf, supporting light to gentle southeast winds over most of the region. Radar imagery shows scattered moderate convection over the NE Gulf and Florida N of 28N between 81W and 87W. A ridge over the northern Gulf will shift E ahead of a cold front moving off the Texas coast this afternoon. The front will extend from the Florida Big Bend area to Veracruz Mexico early Tue, just as a reinforcing push of cold air moves off the Texas coast. The reinforcing cold air will strengthen the front late Tue as strong winds and building seas develop over the northern Gulf. The front will exit SE of the Gulf by early Wed. Winds and seas diminish across the Gulf Thu and Fri as high pressure follows the front across the northern Gulf. CARIBBEAN SEA... A pair of scatterometer passes confirmed a large area of fresh to strong trade winds off Colombia, and a smaller area of strong winds south of the Bay Islands off central Honduras. Seas are reaching 8 ft off Colombia, but are generally 4 to 6 ft in the eastern and central Caribbean and tropical north Atlantic, and 2 to 4 ft in the northwest Caribbean. No significant convection is noted. High pressure north of the region will support fresh to locally strong trades across the south central Caribbean the next several days. Winds will reach near gale force along the NW coast of Colombia during the overnight hours. A weakening cold front will pass through the Yucatan Basin late Tue night. A tight pressure gradient ahead of the front will generate fresh to strong E to SE winds off the central coast of Honduras through Tue. Undersea volcano Kick em Jenny, north of Grenada near 12.18N 61.38W, is in a state of unrest. The government of Grenada advises mariners to observe a 5 km or 3.1 nm exclusion zone around Kick em Jenny. Please see www.nadma.gd for additional information. ATLANTIC OCEAN... Please see Special Features section for information on the developing gale warning in the Atlantic. A cold front is over the W Atlantic from 31N57W to 27N70W. Scattered moderate convection is within 60 nm of the front. The front will shift eastward and weaken through Tue. Farther south, weak ridging is supporting gentle breezes west of 60W, with 4 to 6 ft seas in open waters east of 75W, due mainly to residual northerly swell. The next cold front will move off the coast late Tue, associated with a deep surface low moving off the mid-Atlantic coast. The supporting upper trough will become negatively tilted as it emerges off the coast. This will interact with the Gulf Stream to support scattered thunderstorms Tue night off the northeast coast of Florida. In addition to the gales, strong westerly winds and seas ranging from 8 ft to as high as 17 ft will prevail north of 27N and west of 60W into Wed night. A 1028 mb high pressure is centered near 31N27W, supporting gentle to moderate NE to E winds over the subtropics and moderate to fresh trades in the deep tropics. An upper trough is noted along 28W north of 05N, supporting a few small areas of modest convection along the monsoon trough and ITCZ. Recent altimeter satellite passes indicate seas are still 8 to 12 ft north of 05N, likely in persistent long period NW swell. A weakening cold front will move east across the waters N of 27N and E of 70W tonight. S to SW flow will increase off NE Florida tonight and Tue ahead of a stronger cold front moving into the region late Tue. Winds will reach gale force north of 28N Tue night through Wed night as the front moves east. Winds and seas will diminish Thu as the front reaches from Bermuda to the Windward Passage, then continues E and slowly weakens. For additional information please visit http://www.hurricanes.gov/marine $$ MT