000 AXNT20 KNHC 231715 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 115 PM EDT Fri Mar 23 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 1700 UTC. ...SPECIAL FEATURES... ...GALE WARNING FOR THE SOUTH-CENTRAL CARIBBEAN SEA... A combination of strong surface high pressure moving east off the U.S. coast and lower pressure over northern South America is expected to support winds to gale force near the coast of Colombia beginning this evening. These winds are expected to be strongest during the evening and overnight hours over the next several days while the surface weather pattern persists. For more details please see High Seas Forecasts issued by the National Weather Service under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC. This information can also be found at the following website: www.nhc.noaa.gov/marine ...MONSOON TROUGH/ITCZ... The monsoon trough extends from Sierra Leone on the African coast near 08N13W to 05N19W. The ITCZ continues from 05N19W to 00N34W to the northeast coast of Brazil near 02S44W. Scattered moderate convection is present from 03N to 05N between 19W and 23W. Similar convection is occurring from 03N to 06N between 10W and 14W. ...DISCUSSION... GULF OF MEXICO... Fair weather prevails across the entire Gulf of Mexico due to the combination of surface high pressure, supported by a 1028 mb high near the Florida-Georgia border, and abundant dry air in the mid- and upper-levels of the atmosphere. The surface winds are out of the northeast to east over the eastern and central Gulf and east to southeast over the western Gulf. The winds are strongest over the southern and western waters, but they are generally less than 20 kt area-wide. Sea heights are highest, near 6 ft, in the Bay of Campeche due to the longer fetch there. Surface high pressure is expected to gradually shift southeastward this weekend, causing winds to turn southerly over much of the region. This flow will cause sea heights to increase a little over the northwestern waters. Fair weather is expected to continue through the weekend as dry air remains in place. CARIBBEAN SEA... 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 refer to the web page, www.nadma.gd, for additional information. Tranquil conditions exist across the Caribbean Sea today with satellite images only showing the typical patches of low clouds and embedded quick-moving showers across the region. The remnants of a cold front from the Windward Passage to northeastern Nicaragua is marked by a wind shift with northeasterly to northerly winds west of that line and easterly flow to the east of that old boundary. Trade winds are strongest over the south- central waters near the coast of Colombia, and these winds are expected to reach gale-force during the evening and overnight hours over the next several days. See the SPECIAL FEATURES section above for more details. Looking ahead to the weekend, the remnants of the cold front is expected to dissipate, leaving the area in more uniform easterly flow and fair weather. ATLANTIC OCEAN... A cold front enters the discussion area near 32N58W and continues southwestward to the Windward Passage. Scattered showers and isolated thunderstorms are possible within 90 n mi east of the front north of 25N. West of the front, surface high pressure dominates the area with northerly flow and cooler air covering the western Atlantic. Strong surface high pressure also dominates the central and eastern Atlantic Ocean anchored by a 1034 mb high near 34N35W. This high is producing fresh to strong trade wind flow across a large portion of the tropical and subtropical eastern Atlantic waters. Despite the surface high pressure, there is an area of showers and thunderstorms from 17N to 23N between 23W and 29W associated with an upper-level low. The front over the central-western Atlantic is expected to slowly shift eastward and weaken while another boundary enters the far northwestern waters this weekend. For additional information please visit http://www.hurricanes.gov/marine $$ Cangialosi