000 AXNT20 KNHC 240004 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 804 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... ...GALE WARNING FOR THE SOUTH-CENTRAL CARIBBEAN SEA... A combination of strong surface high pressure ridging southward along the U.S. east coast and relatively strong low pressure over northern South America is expected to support winds to gale force near the coast of Colombia beginning this evening. The gale force winds will not be continuous but are expected to recur each night during the evening and overnight hours through the end of next week while this 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 04N19W. The ITCZ continues from 04N19W to 01N31W to the northeast coast of Brazil near 03S45W. Scattered moderate and isolated strong convection is present from 02N to 05N between 07W and 20W. Similar convection is occurring from 03S to 00N between 38W and 44W. ...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 merely 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 through Thu night and Fri morning. 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 stationary front enters the discussion area near 32N58W and continues southwestward to 23N68W, then continues as a weakening stationary front to the Windward Passage. Scattered showers and isolated thunderstorms are observed along and up to 90 n mi SE of the front N of 24N, while cloudiness and patchy rain are seen along and up to 90 nm NW of this boundary N of 24N. 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 35N34W. 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 16N to 18N between 31W and 39W 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 $$ McElroy